Background: Preliminary data suggest that Atrial Fibrillation (AFib) is common in patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) and present at a younger age than in controls. Whether AFib is also a marker of increased severity for ARVC has not been investigated.
Objectives: 1)To assess the prevalence and the characteristics of AFib in a cohort of 267 ARVC patients without a previous cardiac arrest;2)To correlate the presence of AFib with structural abnormalities of the heart;3)To assess the role of AFib as risk factor for the occurrence of a first Life-Threatening Arrhythmic Event (LAE: sudden cardiac death, aborted cardiac arrest or syncopal ventricular tachycardia) and for cardiovascular death (CVD) in ARVC patients, during a median follow-up of 6 years.
Methods: Consecutive ARVC patients. Clinical course determined with Kaplan-Meier method; predictors of LAE and CVD determined with Cox multivariable analysis.
Results: Overall, 24/267 (9%)ARVC patients experienced ≥1 episodes of AFib during 5.8 years of follow-up (75% males, age at AFib onset: 50±19years). AFib was observed as an early manifestation of ARVC in 42% of the patients, occurring in the context of a structurally normal heart in 52% of the cases. As compared to patients without atrial arrhythmias, subjects with AFib showed similar ventricular function (p=0.9 for right ventricular ejection fraction; p=0.9 for left ventricular ejection fraction), tricuspid regurgitation (p=0.25), and atrial size (p=0.5 for right atrial volume, p=0.3 for left atrial volume). In the multivariable analysis, the presence of AFib was associated with a higher risk of experiencing a first LAE (hazard ratio, HR 4, p=0.002) and of CVD (HR 11; p=0.004) during follow-up, independently from the established risk factors in ARVC.
Conclusions: The prevalence of AFib approached 10% in our ARVC patients and it was not associated with more advanced structural abnormalities. However, patients with AFib experienced a significantly higher risk of life-threatening arrhythmias and cardiovascular death during follow-up. AFib might therefore reflect the presence of electrical instability, suggesting that atrial involvement be a surrogate marker of a more severe predisposition to arrhythmias in ARVC.