Atrial Dysfunction in Arrhythmogenic Right Ventricular Cardiomyopathy.

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy that is predominantly known to affect the ventricles. Evidence for atrial involvement remains limited. Therefore, we aimed to characterize atrial involvement in ARVC using functional cardiac magnetic resonance, define the extent of atrial size and function variation attributable to ventricular variables, and identify cardiac magnetic resonance-based predictors of atrial arrhythmias (AA) in ARVC.

Methods And Results: We analyzed cine cardiac magnetic resonance images of 66 definite ARVC patients without a history of AA or severe heart failure and 24 healthy controls. Using tissue tracking, we evaluated phasic biatrial volumes, ejection fractions (EFs), peak longitudinal strain, and strain rates (SRs). The primary outcome was the occurrence of AA during 6.8 years [3.0-10.8 years] of follow-up. Compared with controls, ARVC patients had higher biatrial volumes, reduced right atrial (RA) conduit function (passive EF [RAEF] and peak early-diastolic SR), reduced RA and left atrial (LA) reservoir function (peak systolic SR), and reduced RA and LA pump function (peak late-diastolic SR; P<0.05). Using multivariable analysis, predictors of increased risk of AA during follow-up were higher atrial volumes (RAV and LAV), decreased LA reservoir function (total LAEF and LA peak longitudinal strain), and decreased RA conduit function (passive RAEF and RA early-diastolic SR).

Conclusions: Compared with controls, patients with ARVC were found to have enlarged atria with decreased function on functional cardiac magnetic resonance examination. RA and LA parameters predict incident AA after adjusting for clinical and ventricular characteristics which suggests atrial involvement in ARVC.