Table 2: Acute Therapy of SVT in Patients with ACHD.

Recommendation for haemodynamically unstable SVT
Electrical cardioversion is recommended (caution for sinus node dysfunction and impaired ventricular function with need for chronotropic or inotropic support)*
IV adenosine for conversion may be considered (caution for sinus node dysfunction and impaired ventricular function with need for chronotropic or inotropic support)
Recommendation for haemodynamically stable AVNRT/AVRT
IV adenosine may be considered
Atrial overdrive pacing (via oesophagus or endocardial) for pace termination may be considered
Recommendation for haemodynamically stable MRAT/AT
IV ibutilide for conversion of atrial flutter may be considered (caution for pro-arrhythmia in patients with impaired ventricular function)
IV metoprolol (caution for hypotension) may be considered for conversion and rate control
Atrial overdrive pacing for pace termination of atrial flutter (via oesophagus or endocardial) may be considered

Scientific evidence that a treatment or procedure is beneficial and effective. Requires at least one randomised trial, or is supported by strong observational evidence and authors’ consensus.

General agreement and/or scientific evidence favour the usefulness/efficacy of a treatment or procedure. May be supported by randomised trials that are based on too small number of patients to allow a green heart recommendation.

*Supported by strong observational evidence and authors’ consensus but no specific RCT. ACHD = adult congenital heart disease; AT = atrial tachycardia; AVRT = AV reentry tachycardia; AVNRT = AV nodal reentry tachycardia; IV = intravenous; MRAT = macro-reentrant atrial tachycardia; RCT = randomised clinical trial; SVT = supraventricular tachycardia.

In the retrospective studies comparing AAD for prevention of SVT in patients with ACHD, only 45 % of the patients were free from SVT after 2.5 years of follow-up.[57] Class III AADs sotalol and amiodarone were the most effective, but adverse effects were common (22 %). Class Ic drugs (encainide and flecainide) should not be used in patients with ACHD due to their proarrhythmic effects (see Table 3).[58] The recent Cochrane Database System Review of randomised trials regarding the safety of AAD compared with controls in adult patients with AF showed that all AADs except amiodarone, dronedarone and propafenone were associated with an increased risk of proarrhythmia.[59] Quinidine, disopyramide and sotalol were additionally associated with increased all-cause mortality rates.[59] There is no reason to expect these drugs to be safer in a population with structural heart disease, such as ACHD, and therefore they cannot be recommended otherwise than as a last-choice therapy. Amiodarone is less often associated with proarrhythmia, but has severe side-effects (thyroid and pulmonary toxicity) that limit long-term use in these patients.[59] Atrial-based pacing does not seem to prevent subsequent atrial arrhythmias according to multivariate analysis.[60]