2019 ESC - supraventricular tachycardia

studies do not confer absolute certainty about risk assessment. In a recent retrospective study in 912 young patients (aged <21 years)

with WPW syndrome, 96 experienced life-threatening events,405 of whom 49% had rapidly conducted pre-excited AF. In patients with events subjected to EPS risk stratification, 22 of 60 (37%) did not have EPS-determined high-risk characteristics, and 15 of 60 (25%) had neither concerning pathway characteristics nor inducible AVRT. There has also been evidence supporting the notion of LV dysfunction related to electrical asynchrony in patients, especially children, with asymptomatic pre-excitation.478 481 It seems reasonable to recommend EPS and consider ablation if a link between pre-excitation and LV dysfunction can be made.

Catheter ablation of an asymptomatic ‘low-risk’ AP also appears reasonable in appropriately experienced centres according to informed patient choice. However, when a decision is made to perform catheter ablation, it is important to recognise that ablation of APs in the anteroseptal or mid-septal (MS) region is associated with a small risk of AV block. The risk of heart block associated with ablation of anteroseptal or MS APs may preclude ablation of an anteroseptal or MS AP in an asymptomatic patient.

Thus, the approach for patients with asymptomatic pre-excitation that does not exhibit high-risk characteristics at EPS depends on the experience and expertise of the electrophysiologist performing the procedure, as well as the preferences and values of the patient. In the CASPED registry involving 182 children and adolescents with asymptomatic pre-excitation, catheter ablation achieved a 91% success rate without significant complications.482

12 Supraventricular tachycardia in adults with congenital heart disease

The number of adults with congenital heart disease is increasing at a rate of 60% per decade in developed countries.483,484 Currently, it is estimated that 1 million adults with congenital heart disease live in the European Union. Despite ongoing advances in paediatric surgery and cardiology, allowing >90% of children born with congenital heart disease to survive to adulthood,485 these patients usually continue to be afflicted by late complications leading to increased morbidity and mortality. Alongside HF, cardiac arrhythmias are a common late complication in adults with congenital heart defects.486 This is due to the underlying cardiac defect, previous or persisting haemodynamic issues, and previous surgical interventions resulting in myocardial damage and scarring.487 Arrhythmic burden ranges from bradycardia arrhythmias to SVTs, and life-threatening VTs or fibrillation.

Owing to preceding operations and underlying anatomy, patients with tetralogy of Fallot, Ebstein’s anomaly, transposition of the great arteries after atrial switch procedure, and complex patients with univentricular hearts and Fontan palliation are especially prone to late development of arrhythmias, such as incisional or intra-atrial re-entry

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

tachycardia, and ventricular tachycardia.488 However, even patients with usually non-complex lesions such as atrial septal defects have an increased life risk of atrial arrhythmias.

In addition to being related to symptoms, SVTs have been reported as risk factors for sudden cardiac death in patients with ACHD. This issue particularly affects patients with obstructive lesions of the systemic ventricle, tetralogy of Fallot, after Fontan operation, and a systemic right ventricle.489,490 Unfortunately, diagnosis and treatment of arrhythmias in ACHD patients is complicated by the unusual nature of tachycardia, complex intracardiac anatomy, and especially by difficulties in accessing the heart, for example due to abnormal venous anatomy (e.g. azygos continuity or previous Fontan operation). As a consequence, specific expertise in patients with ACHD and access to adequate electrophysiological tools are required when performing catheter ablation procedures in these patients.

12.1 Pharmacological antiarrhythmic therapy

Acute therapy of SVT in the context of ACHD is as described for narrow QRS SVT, in general.491,492 Randomized controlled trials of chronic antiarrhythmic therapy in patients with complex ACHD are lacking. All antiarrhythmic drugs carry a proarrhythmic risk, and many patients with ACHD have underlying sinus node dysfunction or a predisposition for AVN disease. Antiarrhythmic drugs should therefore be used with particular caution, and are generally reserved for symptomatic patients after options for catheter ablation procedures and haemodynamic optimization (e.g. correction of underlying valvular problems) have been exhausted. Beta-blockers may be used to slow AV nodal conduction and may be considered, with caution, in patients with transposition of the great arteries after the atrial switch operation. This is supported by studies reporting a reduction in ventricular fibrillation and/or appropriate ICD shocks in patients treated with beta-blocking drugs.493,494 However, care is needed as these patients may suffer from chronotropic incompetence and cannot tolerate beta-blockade.495 Owing to recognized pro-arrhythmic effects, class IC drugs should be used with appropriate caution in the ACHD setting. Similar considerations refer to quinidine, disopyramide, and sotalol. In the recent report of the DARE study cohort, amiodarone, flecainide, and sotalol were clearly found to be pro-arrhythmic, especially in the presence of a prolonged QT, in older women, and in patients with underlying cardiovascular comorbidity, family history of sudden death, and hypokalaemia.496 Flecainide is highly effective in infants with SVT, but there are concerns about its toxicity at older ages.496,497 Most centres have a lower threshold for the use of amiodarone in patients with ACHD as it is perceived to be less proarrhythmic. However, it is commonly associated with thyroid disorders and less commonly with other well-described potentially life-changing complications. These considerations should severely limit its long-term use in patients with ACHD, thus further supporting the first-line use of ablation attempts wherever possible.498

12.2 Catheter and surgical ablation

Owing to underlying anatomy and previous operations, interventional access for ablation procedures may be challenging in patients with ACHD. In addition, the nature of SVT is often atypical, and related to multiple re-entrant circuits and fibrotic atrial tissue. As a consequence, special expertise and experience with ablation of complex tachyarrhythmias and scar-related procedures are necessary.506 It is recommended that patients with complex incisional tachycardias are referred to specialist centres with adequate experience, volumes of ablation procedures, and advanced mapping capabilities. Catheter ablation procedures in the setting of ACHD are associated with lower success rates compared with the general cohort of patients with AF or atrial flutter.484 However, ablation of CTI-related arrhythmias has been reported to have a high acute success rate (>95%), although the mid-term recurrence rate may approach 20%.507 Pre-operative catheter ablation or concomitant arrhythmia surgery should be considered in patients with ACHD undergoing cardiac surgery, as its incorporation can result in improved functional class and potentially decreased requirements for chronic antiarrhythmic medication in this vulnerable population.502 504

12.3 Specific disease states

12.3.1 Atrial septal defect

The incidence of atrial arrhythmias in patients with atrial septal defects ranges between 5 15%.508 The exact impact of atrial septal defect closure, especially of late closure, on the risk of developing AT is controversial. Patients commonly present with RA MRAT. The leading

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

mechanism is CTI-dependent tachycardia and this is generally susceptible to catheter ablation. However, CTI-dependent and ‘incisional’ atrial flutter may coexist. Closure of an existing atrial septal defect, in isolation, is generally insufficient to abolish an existing AT and catheter ablation should be considered before defect closure. Mid-term recurrence rates of 40 44% have been reported in atrial septal defect patients post-flutter or AF ablation508,509; however, this should not preclude ablation procedures wherever possible.

12.3.2 Ebstein’s anomaly

ATs are common in Ebstein’s anomaly, occurring in 25 65% of patients.501,510 512 The types of arrhythmia include atrial flutter, focal AT, and AF. In addition, 10 45% of patients have right-sided APs, including WPW syndrome. More than one AP is common in this setting, and can in itself increase the risk of haemodynamic compromise and sudden cardiac death. Catheter ablation of APs has a high success rate; however, ablation procedures may be challenging and repeat procedures may be necessary as some patients have multiple ablation targets. In addition, patients may develop different arrhythmia mechanisms following ablation.501 In patients undergoing surgical repair, routine pre-operative EPS can be recommended as the diagnostic and therapeutic yield in this population is high.513

12.3.3 Transposition of the great arteries (dextrotransposition of the great arteries) after atrial switch operation (Mustard or Senning)

Owing to previous surgery and scarring, atrial re-entrant tachycardias are common in patients with a Mustard or Senning repair. In addition,

sinus node dysfunction may occur as a consequence of the atrial redirection procedure.495 As tachycardia is not well tolerated in patients with asystemic right ventricular and diastolic dysfunction, maintaining long-term sinus rhythm is highly desirable in this setting. Use of antiarrhythmic drugs is limited due to ventricular and sinus node dysfunction, and pro-arrhythmic risk. Ablation procedures in patients with a Mustard or Senning repair have a high acute success rate; however, recurrence rates approach 30% during long-term follow-up.500,514 516

12.3.4 Tetralogy of Fallot

SVTs are not uncommon in patients with tetralogy of Fallot. In addition to being related to symptoms, the occurrence of supraventricular arrhythmias has been linked to a statistically higher risk of sudden cardiac death in this population.517 As catheter ablation has a high procedural success rate, it should be considered as a first-line option in this setting.518 In addition, patients with new-onset atrial arrhythmias should be thoroughly evaluated to exclude addressable haemodynamic lesions such as severe pulmonary valve regurgitation, which may be amenable to surgical or interventional therapy leading indirectly to reduced arrhythmia burden.

12.3.5 Fontan repairs

AT is common in patients post-Fontan palliation. Patients with a classic (atriopulmonary) Fontan procedure are at especially high risk for AT, with <60% developing SVTs after 15 years of follow-up.519 In addition to symptoms and the risk of cardiac thromboembolism, AT is poorly tolerated haemodynamically in patients with univentricular hearts, and may lead to acute deterioration and overt HF in this setting.520 Catheter ablation is often effective but challenging, due to the nature of the arrhythmia circuits as well as issues with cardiac access.514,515 Various surgical modifications, such as the conversion to total cavopulmonary connection, have evolved and can ameliorate the risk of atrial arrhythmias.521

13 Supraventricular tachycardia in the paediatric population

Specific detailed recommendations for paediatric patients are published elsewhere522,523 and are beyond the scope of this document. In general, certain aspects are different in the paediatric population and should be taken into account.

Immaturity of the cardiac structures, including conduction tissue, may lead to modifications in the electrophysiology of the heart. Therefore, some APs present in the first months of life (even those associated with tachycardias) may disappear before the first year of age.522 Actually, AVRT due to WPW that begins in infancy may resolve in 90% of patients, but may recur in later childhood in

30 - 50% of patients; however, if the tachycardia is present after the age of 5, it persists in >75% of patients.524

It is clear that small children may not complain of symptoms, so indirect signs have to be assessed when SVT is suspected, i.e. irritability, failure to thrive, and even flat growing curves. It is not uncommon to discover an incessant SVT in a patient presenting with cardiogenic

shock due to TCM. This most frequently occurs in relatively slow SVTs, such as PJRT and focal AT.525,526

Pharmacokinetics and pharmacodynamics in children are different to those in adults; therefore, special attention has to be given when prescribing drugs.527 This is particularly important in newborns as

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

milk can substantially modify the absorption of the drug and, as feeding schedules tend to be erratic, can affect effective drug availability. Furthermore, many drugs have to be prepared at specialized pharmacies, adding to the risk of incorrect dosing, and drug solutions may also need to be stored under special conditions to maintain their stability. This can be inconvenient when long-term treatment is required as, for example, a portable cooler bag must be carried. In addition, the long-term effects of some drugs, as they accumulate, are especially dangerous in growing bodies. This is of special interest regarding amiodarone, which can chronically provoke the same secondary effects as it does in adults. Verapamil has to be avoided whenever possible or given very carefully to small patients as it can provoke severe hypotension.522 A decreased response of adenosine in younger children has also been suggested.528

Invasive techniques are possible and effective even in very small children, when indicated, but there are several limiting factors. First, radiofrequency lesion formation in immature sheep myocardium is similar to that in adult sheep myocardium acutely, but is associated with late lesion enlargement and fibrous tissue invasion of normal myocardium. These observations may have implications for clinical radiofrequency ablation procedures in infants529 and avoidance of radiofrequency ablation, if at all possible, in the first 2 years of life is prudent. Second, no specific catheters and tools exist for the paediatric population. Currently, available catheters (minimum 5 French for non-irrigated radiofrequency tips) and curves are, in general, too large. This is particularly limiting in small children needing an ablation to resolve incessant tachycardia. Finally, the experience of the operator and the centre is crucial. Small patients requiring ablation should be referred to experienced reference centres for treatment. The number of catheters used, and procedural and radiation times, should be minimized in these growing bodies.530 Electroanatomical mapping systems are most valuable in this setting.

13.1 Foetal arrhythmias

Foetal arrhythmias can be detected at an early gestational age, with incessant, rapid SVTs associated with foetal death due to hydrops. Therefore, a special effort has to be made to detect and control foetal arrhythmias. A strong correlation between post-natal SVT and later gestational age at foetal SVT diagnosis has been reported.531 Diagnosis relies on echocardiography as foetal ECGs are not available in most clinics (it is used in just a few centres worldwide and primarily for research purposes).532 When sustained foetal tachycardia is observed, treatment is mandated. There are several protocols for this purpose, and they are mostly based on digoxin, flecainide, and sotalol alone or in combination depending on the type of tachycardia. These drugs have to be given to the mother, with a fraction reaching the foetus. This means that the secondary effects of these drugs can manifest in both the foetus and mother. Close follow-up is therefore needed.522,533,534

14 Supraventricular tachycardia in pregnancy

Sustained SVT becomes more frequent during pregnancy, occurring in 22 24/100 000 pregnancies. It may even manifest for the first time, particularly in the third trimester or peri-partum, according to comprehensive discharge data from hospitals.535 The overall

frequency of any arrhythmia is greater in women aged 41 50 years (199/100 000) than in those aged 18 30 years (55/100 000), which may be due to more prevalent AF and VT, whereas SVT seems stable over time.535 Arrhythmias are also more frequent among women with congenital heart disease, particularly atrial flutter, compared with women without congenital defects.536

As substantive prospective or randomized studies are unavailable, recommendations are primarily based on small cohorts or case reports in conjunction with expert opinion.

14.1 Maternal, obstetric, and offspring risk

SVT is associated with an increased risk of death during pregnancy, and the reported frequency is 68 per 100 000 pregnancy-related hospitalizations for any arrhythmia, 22 per 100 000 for SVT, 4 per 100 000 for atrial flutter, 27 per 100 000 for AF, 2 per 100 000 for ventricular fibrillation, and 16 per 100 000 for VT.535

Identification and treatment of underlying conditions are the first priorities. Although most of the exacerbations of SVT during pregnancy are benign and can be treated effectively with standard medical therapy,537 the circumstances that should be considered include the well-being of the foetus and the effects on labour, delivery, and lactation. The haemodynamic effect of tachycardia, as well as side effects of treatments, must be balanced and addressed for the foetus. Catheter ablation should therefore be considered before pregnancy when possible in patients with a known history of symptomatic tachyarrhythmia. Trials evaluating the level of surveillance at delivery are needed.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

14.2 Therapy

14.2.1 Antiarrhythmic drugs

Treatment with antiarrhythmic drugs for the prevention of SVT should, in general, be reserved for SVTs causing haemodynamic compromise or significant symptoms. The major concern regarding the use of antiarrhythmic drugs during pregnancy is potential adverse effects on the foetus. While the first trimester is associated with the greatest teratogenic risk, drug exposure later in pregnancy may result in adverse effects on foetal growth and development, and on uterine contractility, and an increased risk of pro-arrhythmia. The risks and benefits of continuing vs. stopping medication must be carefully considered in terms of the risk of recurring SVT, and the potential for haemodynamic compromise. Decisions should be individualized, based on the clinical situation and possible additional structural heart disease. Major controlled studies of antiarrhythmic drugs during pregnancy are lacking. If non-invasive manoeuvres fail, adenosine should be the first-line drug for treatment if needed during the second and third trimesters. There is a paucity of data on management of SVT in the first trimester.542 All beta-blockers can cause bradycardia and hypoglycaemia in the foetus. As beta-1 selective beta-blockers are less likely to affect uterine relaxation, they are preferred.546 Maternal use of beta-blockers in the first trimester has not been associated with a large increase in the risk for overall or cardiac malformations.548,553 However, in the EUROmediCAT study, an association between alpha/beta-adrenergic blocker use in the first trimester with multicystic renal dysplasia was reported.554 There have been concerns about ‘low weight for gestational age’ with beta-blockers, although the effects reported may not be large enough to be of clinical importance. Exposure to atenolol has been associated with a

higher risk of infants born small for their gestational age compared with metoprolol and propranolol, consistent with this association not being a class effect.543,555 Diltiazem has been found to be teratogenic in animals, with only limited human data, and its use is not generally recommended in pregnancy. Verapamil is considered safer than diltiazem and could be used as a second-line drug.153,543

14.2.2 Electrical cardioversion

Electrical cardioversion should be the first choice when arrhythmias are haemodynamically unstable. Cardioversion seems safe in all phases of pregnancy as it does not compromise foetal blood flow, and has low risk of inducing foetal arrhythmias or initiating pre-term labour.539 The foetal heart rate should be routinely controlled after cardioversion.

14.2.3 Catheter ablation

Catheter ablation should be postponed to the second trimester if possible, but may be necessary in the case of drug-refractory and poorly tolerated tachycardia. It should then be performed at an experienced centre using non-fluoroscopic electroanatomical mapping and catheter navigation systems.556 Catheter ablation of recurrent, drug-refractory AVNRT, AVRT, focal AT, and CTI-dependent atrial flutter has been successful during pregnancy.550 552

15 Tachycardia-induced cardiomyopathy

15.1 Definition

Tachycardia-induced cardiomyopathy (TCM), or more accurately arrhythmia-induced cardiomyopathy, is a reversible cause of impaired LV function due to persistent tachycardia or very frequent ventricular premature beats that can lead to HF and death. The incidence of TCM is unknown but has been reported in all age groups, from foetuses to the elderly.

15.2 Mechanism

The syndrome was initially described with PJRT, but we now know that any chronic cardiac arrhythmia may cause TCM. Incessant AVRTs due to septal APs, rapid AF, idiopathic VT, AT, and persistent ectopic beats are best described.196,233,526,557 563 In patients aged <18 years, focal AT is the commonest cause.408

Rapid pacing in animal models induces cytoskeletal changes and remodelling of the extracellular matrix attributed to abnormal calcium cycling, increased catecholamines, decreased beta-1 adrenergic receptor density, oxidative stress, depletion of myocardial energy stores, and myocardial ischaemia due to increased heart rate.559,564 Endomyocardial biopsy specimens from patients with TCM exhibit features distinct from those of other types of cardiomyopathy, including deranged cardiomyocyte and mitochondrial morphology, and macrophage-dominated cardiac inflammation.565 However, it has not been fully established how the majority of patients with frequent premature ventricular contractions have a benign course, whereas <30% of them may develop cardiomyopathy.566

.	15.3 Diagnosis
..
.
.	TCM is one of the very few reversible causes of HF and dilated cardi-
.
.
.	omyopathy, and should be considered in any patient with new onset
.
.
.	of LV dysfunction. In the presence of persistent or frequent tachycar-
.
.
.
. dia, or frequent premature ventricular contractions, a high index of
.
.	suspicion	should be maintained. The diagnosis is established by
.
.
.	excluding other causes of cardiomyopathy, and demonstrating recov-
.
.
.	ery of LV function after eradication of the arrhythmia or control of
.
.
.	the ventricular rate. Typically in TCM, LV ejection fraction is <30%,
.
.
.	LV end-diastolic diameter is <65 mm, and LV end-systolic diameter is
.
.	557
.
.	<50 mm.	More dilated ventricular volumes suggest underlying
.
.	dilated cardiomyopathy, although some overlapping of the two con-
.
.
.	ditions can occur. In patients with suspected TCM, cardiac magnetic
.
.
.	resonance (CMR) is advisable to exclude intrinsic structural change.
.
.
.	Serial assessment of N-terminal pro-B-type natriuretic peptide (NT-
.
.
.	proBNP) and estimation of the ratio of NT-proBNP at baseline to
.
.
.	NT-proBNP during follow-up can help differentiate TCM from irre-
.
.
.	versible idiopathic dilated cardiomyopathy.
.
.
.
.
.
.
.	15.4 Therapy
.

Recommendations for the therapy of supraventricular tachycardia in patients with suspected or established heart failure due to tachycardiomyopathy

Recommendation

Classa Levelb

	Catheter ablation is recommended for TCM	I	B
	due to SVT.196,233,418,525
	Beta-blockers (from the list with proved mor-
	tality and morbidity benefits in HFrEF) are rec-	I	A
	ommended for TCM due to SVT, when
	catheter ablation fails or is not applicable.567
	It is recommended that TCM is considered in
	a patient with reduced LV ejection fraction	I	B
	with an elevated heart rate (>100
	b.p.m.).557 561

24 h (or multiday) ambulatory ECG monitor-
ing should be considered for diagnosis of TCM	IIa	B
by identifying subclinical or intermittent
arrhythmias.526,557,568
AV nodal ablation with subsequent pacing
(‘ablate and pace’), either biventricular or His-
bundle pacing, is recommended if the tachy-	I	C
cardia responsible for the TCM cannot be
ablated or controlled by
drugs.526,557,564,569 572

b.p.m. = beats per minute; ECG = electrocardiogram; HFrEF = heart failure with reduced ejection fraction; LV = left ventricular; SVT = supraventricular tachycardia; TCM = tachycardiomyopathy.

aClass of recommendation. bLevel of evidence.

In TCM, LV function frequently improves after 3 months of restoration of a normal heart rate. In IST, beta-blockers are indicated. Catheter ablation is indicated when TCM is due to another SVT. When the tachycardia itself cannot be ablated, AV nodal ablation

with either biventricular or His-bundle pacing is appropriate.569 572 Long-term medical therapy with beta-blockers, and angiotensinconverting enzyme inhibitors or angiotensin II receptor blockers, is indicated before and after successful ablation for the known beneficial effects of these drugs on the LV remodelling process. Given the risk of recurrence of arrhythmias, long-term monitoring of patients is recommended.

16 Supraventricular tachycardia in sports

Athletes with frequent supraventricular arrhythmias should be assessed to exclude the presence of an underlying cardiac disease, electrolyte imbalance, thyroid dysfunction, and the use of stimulants or performance-enhancing drugs. Table 13 outlines the recommendations for sports eligibility of patients with SVT.573,574

Ventricular pre-excitation (WPW syndrome) is a rare cause of sudden cardiac death in young athletes.575 Although many individuals with ventricular pre-excitation remain asymptomatic throughout their lives, symptomatic AVRT may occur. Patients with WPW may also develop other arrhythmias, such as AF, which could degenerate into ventricular fibrillation and sudden cardiac death. Because sports activity has been associated with an increased risk of AF,576 athletes with ventricular pre-excitation have an increased risk of sudden cardiac death if the AP has the potential for fast antegrade conduction. Thus, catheter ablation of the AP is currently recommended in symptomatic athletes with ventricular pre-excitation. Asymptomatic athletes with intermittent pre-excitation (at rest or during exercise) or abrupt disappearance of pre-excitation during stress testing may be considered to be at low risk (see section 11.3.11 for reservations), but should be further evaluated as they may be eligible for competitive sports activity. In asymptomatic athletes with ventricular pre-excitation, invasive risk stratification should be conducted as described in section 11.3.11 and catheter ablation should be

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

performed in those with high-risk features.577 Asymptomatic patients stratified at low risk are allowed to practice competitive sports.

AVNRT, orthodromic AVRT over a concealed AP, and AT are not listed among the causes of sudden cardiac death during exercise in patients with a structurally normal heart. However, their occurrence during sports activity may be associated with very high heart rate because of sympathetic stimulation and may cause haemodynamic impairment even in patients with structurally normal hearts. Accordingly, catheter ablation should generally be recommended for all athletes with a history of paroxysmal SVT. Athletes with SVT who do not wish to undergo catheter ablation, or in whom the procedure has been unsuccessful, may be considered eligible for competitive sports activity if the arrhythmia is sporadic, unrelated to cardiac disease, well tolerated, and unrelated to exercise, and when the sports activity does not have a high intrinsic risk of loss of consciousness (such as divers, pilots, horse riders, etc.).578

Treatment of paroxysmal SVT with beta-blockers or sodium channel blockers is discouraged in athletes, because these drugs may reduce performance during sports and have limited ability to prevent arrhythmia recurrence during sports activity. Moreover, betablockers are listed by the World Anti-Doping Agency as prohibited drugs in particular sports.

17 Supraventricular tachycardia and driving restrictions

The frequency of which medical causes contribute to motor vehicle accidents is not precisely known. Data on arrhythmias as a cause of motor vehicle accidents are hard to obtain due to the difficulty of documenting such events in the general population. However, the proportion is believed to be small, with 1 - 3% of all motor vehicle accidents established as being due to a driver’s sudden incapacitation.579 Of these accidents, 5 - 10% are related to cardiac causes, with

or without syncope, while <2% of cases of reported sudden driver incapacitation have resulted in injury or death to bystanders, or other road users.579

In 2013, a Working Group of the ESC published detailed recommendations on driving restriction in patients with SVT (Table 14).580 Two groups of drivers are considered. Group 1 comprises drivers of motorcycles, cars, and other small vehicles with and without a trailer. Group 2 includes drivers of vehicles over 3500 kg or passengercarrying vehicles exceeding eight seats excluding the driver. Drivers of taxicabs, small ambulances, and other vehicles form an intermediate category between the ordinary private driver and the vocational driver.

18 Key messages

•Not all SVTs are arrhythmias of the young.

•Vagal manoeuvres and adenosine are the treatments of choice for the acute therapy of SVT, and may also provide important diagnostic information.

•Verapamil is not recommended in wide QRS-complex tachycardia of unknown aetiology.

•Consider using ivabradine, when indicated, together with a betablocker.

•In all re-entrant and most focal arrhythmias, catheter ablation should be offered as an initial choice to patients, after having explained in detail the potential risks and benefits.

•Patients with macro-re-entrant tachycardias following atrial surgery should be referred to specialized centres for ablation.

•In post-AF ablation ATs, focal or macro-re-entrant, ablation should be deferred for >3 months after AF ablation, when possible.

•Ablate AVNRT, typical or atypical, with lesions in the anatomical area of the nodal extensions, either from the right or left septum.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

•AVNRT, typical or atypical, can now be ablated with almost no risk of AV block.

•Do not use sotalol in patients with SVT.

•Do not use flecainide or propafenone in patients with LBBB, or ischaemic or structural heart disease.

•Do not use amiodarone in pre-excited AF.

•One in five patients with asymptomatic pre-excitation will develop an arrhythmia related to their AP during follow-up.

•The risk of cardiac arrest/ventricular fibrillation in a patient with asymptomatic pre-excitation is 2.4 per 1000 person-years.

•Non-invasive screening may be used for risk stratification of patients with asymptomatic pre-excitation, but its predictive ability remains modest.

•Invasive assessment with an EPS is recommended in patients with asymptomatic pre-excitation who either have high-risk occupations or are competitive athletes.

•If a patient undergoes assessment with an EPS and is found to have an AP with ‘high-risk’ characteristics, catheter ablation should be performed.

•If possible, avoid all antiarrhythmic drugs during the first trimester of pregnancy. If beta-blockers are necessary, use only beta-1 selective agents (but not atenolol).

•If ablation is necessary during pregnancy, use non-fluoroscopic mapping.

•Consider TCM in patients with reduced LV function and SVT.

•Ablation is the treatment of choice for TCM due to SVT. AV nodal ablation with subsequent biventricular or His-bundle pacing (‘ablate and pace’) should be considered if the SVT cannot be ablated.

19 Gaps in the evidence

•The distinction between triggered activity and enhanced automaticity is not straightforward, as the two mechanisms share many similar responses and characteristics, such as enhancement by

adrenergic activation and suppressed by L-type Ca2þ current blockade.

•Re-entrant circuits may be microscopic or simulate foci by surface ‘breakthrough’ of transmural propagation. Thus, mapping may be inadequate to distinguish them from automatic/triggered activity.

•The exact circuit of AVNRT, the most common regular arrhythmia in the human, remains unresolved.

•The potential role of connexin proteins in AVNRT, and SVT in general, is under investigation.

•Both invasive and non-invasive tests for the risk assessment of patients with asymptomatic pre-excitation have limitations, being dependent on the autonomic tone. More accurate risk-stratifica- tion models are needed.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

•The proper management of asymptomatic pre-excitation and strict catheter ablation indications have not been established.

•The genetics of SVT have not been adequately studied. There has been evidence for familial forms of AVNRT, AVRT, sinus tachycardia, and AT, but data are scarce.

•Novel electroanatomical mapping systems now allow the simultaneous visualization of activation and voltage. The implications that this may have on characterizing the tachycardia substrate, and not just the circuit, require future research.

•Mathematical modelling and numerical analysis of recorded ECGs, using fast Fourier and Gaussian models, may be helpful for the future of artificial intelligence applications in the differential diagnosis of narrow and wide QRS-complex tachycardias, but experience is limited.

21 Areas for further research

With the advent of catheter ablation in the 1990s, resulting in the successful elimination of APs in symptomatic patients, AVRT now represents <20% of all SVTs.11,13 The frequency of AVNRT, which used to account for 50% of all SVT cases,14 has changed to30%,11,13 and the proliferation of AF ablation will unavoidably result in more iatrogenic left atrial MRAT. Moreover, the prolonged survival of paediatric and ACHD patients is expected to impose a further challenge on electrophysiologists, who will encounter even more complex MRATs. Several important advances in the field of anatomical and electrical mapping, as well as our appreciation of scar tissue and the transmurality of ablation lesions, should improve our efficiency in treating these patients.

The past decade has witnessed a rapid evolution of ablation equipment and electrode-guiding systems, which has resulted in more controllable and safer procedures. Intracardiac echocardiography,

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

robotic techniques, and sophisticated anatomical navigation systems have been developed, and it is now possible to perform ablation without exposing the operator to radiation and ergonomically unfavourable positions.581 New materials for electrodes and other equipment have allowed the concept of a radiation-free electrophysiology laboratory with the use of CMR. The vision of a fully radiation-free, magnetic laboratory in the future is not science fiction anymore.582

The revolution in computer technology offers not only improved mapping and electrode-moving systems, but also the enhancement of specific SVT classification schemes with fully automated algorithms that may greatly assist emergency departments, ambulances, and monitored patients.583 Mathematical modelling and numerical analyses have also been employed in the investigation of the circuit of AVNRT.317,329 Further analysis of recorded ECGs using fast Fourier and Gaussian models may also provide useful diagnostic information about the nature of the tachycardia. Novel electroanatomical mapping systems are being developed to assist the identification of the

tachycardia mechanism and optimal ablation site of SVT, and, especially, complex atrial macro-re-entrant tachycardias, with reduced fluoroscopy times.584 589 Systems are now available that allow the simultaneous visualization of activation and voltage. The implications that these may have on characterizing the tachycardia substrate, and not just the circuit, require future research.

New data on the genetics of SVT continually appear since the identification of a missense mutation in the PRKAG2 gene, which encodes the regulatory c-subunit of adenosine monophosphate (AMP)-activated protein kinase, as a cause of familial WPW syndrome.590,591 The R302Q mutation in PRKAG2 has been associated with Mahaim fibers.592 A novel form of WPW syndrome is associated with microdeletion of the BMP2 gene, which encodes bone morphogenetic protein-2, a member of the transforming growth factor-beta gene superfamily, and affects the development of annulus fibrosus.593 Other rare, genetic forms of pre-excitation have also been described.398 Whether this kind of genetic predisposition translates into a higher ventricular fibrillation risk remains to be seen. Genetic animal models of WPW that express mutations (such as of the gene encoding the AMP-activated protein kinase) responsible for a familial form of WPW syndrome with a phenotype identical to that of the human syndrome have been developed, and may provide insight into the development and properties of the cardiac conduction system and APs.594 Spontaneous AVNRT has also been identified as a potential first clinical manifestation of concealed Brugada syndrome, particularly in female patients.595 It has been postulated that genetic variants that reduce the sodium current may predispose individuals to expression of both phenotypes. Cellular electrophysiology is now being integrated into genetic analysis. The coupling of wholeexome sequencing with cellular electrophysiological functional analysis may elucidate the underlying pathophysiological mechanism responsible for certain phenotypes.596 Recently, a familial form of IST was shown to be associated with a gain-of-function mutation in the HCN4 pacemaker channel (R524Q), conferring an increased sensitivity to the second messenger cyclic AMP, which is a key mediator in sympathetic modulation.597 These developments may have important implications for a more specific diagnostic and personalized therapeutic approach in SVT. Future research should define actionable patient-specific molecular arrhythmia mechanisms, clarify the responses of the underlying substrates to interventions, and achieve selective supraventricular targeting of specific arrhythmic mechanisms with drugs.

SVTs are not only an everyday clinical problem, with AVNRT being the most common regular arrhythmia in humans. They also provide the background for proper training of future electrophysiologists by means of their well-defined circuits, in most cases, and predictable responses in the electrophysiology laboratory. In the era of computerized approaches that are now available for AF, complex AT, and VT ablation, this is very important for a rational, Aristotelian approach to the art of medicine.598

22 Supplementary data

Supplementary Data with additional Supplementary Figures and text complementing the full text, as well as sections on the electrophysiological mechanisms of SVT, tachycardia circuits, and cardiac anatomy for the

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

electrophysiologist, along with the related supplementary references, are available on the European Heart Journal website and via the ESC website at www.escardio.org/guidelines.

23 Appendix

Author/Task Force Member Affiliations

Elena Arbelo, Arrhythmia Unit, Cardiovascular Institute, Hospital Clinic de Barcelona, Universitat de Barcelona, Spain; Cardiovascular Institute, Hospital Clınic, Universitat de Barcelona, Barcelona, Spain; and Institut d’Investigacio August Pi i Sunyer (IDIBAPS), Centro de Investigacion Biome´dica en Red de Enfermedades; Barcelona, Spain; Fernando Arribas, Department of Cardiology, Hospital 12 de Octubre, Madrid, Spain; Jeroen J. Bax, Cardiology, Leiden University Medical Center, Leiden, Netherlands; Carina Blomstro¨m- Lundqvist, Department of Medical Science and Cardiology, Uppsala University, Uppsala, Sweden; Hugh Calkins, Cardiology, John Hopkins Medical Institutions, Baltimore, United States of America; Spyridon G. Deftereos, 2nd Department of Cardioloy, National and Kapodistrian University of Athens, Athens, Greece; Gerhard-Paul Diller, Cardiology III, University Hospital Muenster, Muenster, Germany; Juan J. Gomez-Doblas, Cardiology, Hospital Universitario Virgen de la Victoria, CIBERG, Malaga, Spain; Bulent Gorenek, Cardiology Department, Eskisehir Osmangazi University, Turkey; Andrew Grace, Department of Cardiology, Royal Papworth Hospital NHS Foundation Trust, Cambridge University Health Partners, Cambridge, United Kingdom; Siew Yen Ho, Cardiac Morphology, Royal Brompton Hospital, London, United Kingdom; Juan-Carlos Kaski, Molecular and Clinical Sciences Research Institute, St George’s University of London, London, United Kingdom; Karl-Heinz Kuck, Cardiology, Asklepios Klinik St. Georg, Hamburg, Germany; Pier David Lambiase, Cardiology, UCL & Barts Heart Centre, London, United Kingdom; Frederic Sacher, Service de Rythmologie, IHU LIRYC/Bordeaux University Hospital, Bordeaux, France; Georgia Sarquella-Brugada, Arrhythmia, Inherited Cardiac Disease and Sudden Death Unit, Hospital Sant Joan de De´u, Barcelona, Spain; Piotr Suwalski, Central Clinical Hospital of the Ministry of Interior and Administration, Centre of Postgraduate Medical Education, Warsaw, Poland; Antonio Zaza, Universita degli Studi Milano-Bicocca, Dipartimento di Biotecnologie e Bioscienze, Bldg U3, p.za della Scienza 2, 20126 Milano, Italy.

ESC Committee for Practice Guidelines (CPG): Stephan Windecker (Chairperson) (Switzerland), Victor Aboyans (France), Colin Baigent (United Kingdom), Jean-Philippe Collet (France), Veronica Dean (France), Victoria Delgado (Netherlands), Donna Fitzsimons (United Kingdom), Chris P. Gale (United Kingdom), Diederick E. Grobbee (Netherlands), Sigrun Halvorsen (Norway), Gerhard Hindricks (Germany), Bernard Iung (France), Peter Ju¨ni (Canada), Hugo

A.Katus (Germany), Ulf Landmesser (Germany), Christophe Leclercq (France), Maddalena Lettino (Italy), Basil S. Lewis (Israel), Bela Merkely (Hungary), Christian Mueller (Switzerland), Steffen E. Petersen (United Kingdom), Anna Sonia Petronio (Italy), Dimitrios J. Richter (Greece), Marco Roffi (Switzerland), Evgeny Shlyakhto (Russian Federation), Iain

A.Simpson (United Kingdom), Miguel Sousa-Uva (Portugal), Rhian M. Touyz (United Kingdom).