Right atrial area and right ventricular outflow tract akinetic length predict sustained tachyarrhythmia in repaired tetralogy of Fallot

Aims: Repaired tetralogy of Fallot (rtoF) patients are at risk of atrial or ventricular tachyarrhythmia and sudden cardiac death. Risk stratification for arrhythmia remains difficult. We investigated whether cardiac anatomy and function predict arrhythmia.

Methods: One-hundred-and-fifty-four adults with rtoF, median age 30.8 (21.9-40.2) years, were studied with a standardised protocol including cardiovascular magnetic resonance (CMR) and prospectively followed up over median 5.6 (4.6-7.0) years for the pre-specified endpoints of new-onset atrial or ventricular tachyarrhythmia (sustained ventricular tachycardia/ventricular fibrillation).

Results: Atrial tachyarrhythmia (n=11) was predicted by maximal right atrial area indexed to body surface area (RAAi) on four-chamber cine-CMR (Hazard ratio 1.17, 95% Confidence Interval 1.07-1.28 per cm(2)/m(2); p=0.0005, survival receiver operating curve; ROC analysis, area under curve; AUC 0.74 [0.66-0.81]; cut-off value 16 cm(2)/m(2)). Atrial arrhythmia-free survival was reduced in patients with RAAi ≥16 cm(2)/m(2) (logrank p=0.0001). Right ventricular (RV) restrictive physiology on echocardiography (n=38) related to higher RAAi (p=0.02) and had similar RV dilatation compared with remaining patients. Ventricular arrhythmia (n=9) was predicted by CMR RV outflow tract (RVOT) akinetic area length (Hazard ratio 1.05, 95% Confidence Interval 1.01-1.09 per mm; p=0.003, survival ROC analysis, AUC 0.77 [0.83-0.61]; cut-off value 30 mm) and decreased RV ejection fraction (Hazard ratio 0.93, 95% Confidence Interval 0.87-0.99 per %; p=0.03). Ventricular arrhythmia-free survival was reduced in patients with RVOT akinetic region length >30 mm (logrank p=0.02).

Conclusion: RAAi predicts atrial arrhythmia and RVOT akinetic region length predicts ventricular arrhythmia in late follow-up of rtoF. These are simple, feasible measurements for inclusion in serial surveillance and risk stratification of rtoF patients.