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............................................................................................................................................................................. 11.2.1.2.1 Acute therapy. Most data on the effectiveness of vagal manoeuvres and adenosine for acute termination of tachycardia are derived from mixed populations of SVT, as described in section 10.1.1 on the acute therapy of SVT in general, but it seems that they are less successful in AVNRT than in AVRT.89,90,102 A single dose of oral diltiazem (120 mg) plus a beta-blocker (i.e. propranolol 80 mg) may convert <_94% of patients, but there is a risk of hypotension, transient AV block, or—rarely—syncope.342,343 Caution is needed in the elderly, and in patients with known sinus or AV nodal conduction disturbances. A single dose of oral flecainide (3 mg/kg) may also be effective, albeit at a lower rate.342,344 Intranasal etripamil is promising (see section 10.1.1).129 Rarely, when vagal manoeuvres and adenosine cannot terminate the tachycardia and hypotension ensues, synchronized DC cardioversion is indicated101 (Figure 14). 11.2.1.2.2 Catheter ablation. A recent randomized clinical trial (RCT) that compared catheter ablation as first-line treatment with antiarrhythmic drugs demonstrated significant benefits in arrhythmiarelated hospitalizations.336 Furthermore, catheter ablation for SVT in general, and AVNRT in particular, is the current treatment of choice for symptomatic patients because it substantially improves quality of life28,345,346 and reduces costs.347349 Slow-pathway modification is effective in both typical and atypical AVNRT.338 Usually, a combined anatomical and mapping approach is employed, with ablation lesions delivered at the inferior part of the triangle of Koch, either from the right or the left septal side.337339,350,351 This approach offers a success rate of 97%, has an 1.34% recurrence rate, and has been associated with a risk of AV block of <1% in previous reports.203,204,352,353 Recent experience indicates that in experienced centres, the procedure can be accomplished in both typical and atypical AVNRT with almost no risk of AV block, by targeting the inferior nodal extension and avoiding the mid-septum, and the roof of the coronary sinus.208,338,354,355 Success rates are lower (82%) and the risk of heart block higher (14%) in patients with adult congenital heart disease (ACHD).356 Usually, recurrences are seen within 3 months following a successful procedure in symptomatic patients who experience frequent episodes of tachycardia,317,329,336,338 but in the young, aged <_18 years, recurrences may be seen as long as 5 years post-ablation.357 IST may occur, but is usually transient and not frequent following slow-pathway ablation.358 Advanced age is not a contraindication for slow-pathway ablation.359 The pre-existence of first-degree heart block carries a higher risk for late AV block and avoidance of extensive slow pathway ablation is preferable under such conditions.360 There is almost no procedure-related mortality.11,13,203205,208 Cryoablation may carry a lower risk of AV block, but is associated with a significantly higher recurrence rate.361363 Its favourable safety profile and higher long-term success rate in younger patients make it especially attractive for the treatment of children.364 AVNRT is a cause of inappropriate shocks in patients with implantable cardioverter defibrillators (ICDs) and, in the case of frequent episodes, catheter ablation is clearly indicated.365 11.2.1.2.3 Chronic therapy. Patients with minimal symptoms and short-lived, infrequent episodes of tachycardia can be followed-up without the need for ablation or long-term pharmacological therapy (Figure 15). Approximately one-half of them may become asymptomatic within the next 13 years.319 Chronic administration of antiarrhythmic drugs decreases the frequency and duration of Chronic therapy Catheter ablation is recommended for symptomatic, recurrent AVNRT.208,336339 I B Diltiazem or verapamil, in patients without HFrEF, or beta-blockers should be considered if ablation is not desirable or feasible.340342 IIa B Abstinence from therapy should be considered for minimally symptomatic patients with very infrequent, short-lived episodes of tachycardia.319 IIa C i.v. verapamil and diltiazem are contraindicated in the presence of hypotension or HFrEF. i.v. beta-blockers are contraindicated in the presence of decompensated heart failure. DC = direct-current; HF = heart failure; HFrEF = heart failure with reduced ejection fraction; i.v. = intravenous. aClass of recommendation. bLevel of evidence. ©ESC 2019 AVNRT Vagal manoeuvres (I B) Vagal manoeuvres (I B) i.v. adenosine (I B) i.v. verapamil or diltiazem (IIa B) i.v. beta-blocker (IIa C) Synchronized cardioversion (I B) No No Yes Yes If ineffective If ineffective If ineffective Patient out of hospital Haemodynamic instability Figure 14 Acute therapy of atrioventricular nodal re-entrant tachycardia. AVNRT = atrioventricular nodal re-entrant tachycardia; i.v. = intravenous. Downloaded from academic.oup.com/eurheartj/article/41/5/655/5556821 by guest on 07 October 2026