Influence of Genotype on Structural Atrial Abnormalities and Atrial Fibrillation or Flutter in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

INTRODUCTION: Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C) is associated with desmosomal mutations. Although desmosomal disruption affects both ventricles and atria, little is known about atrial involvement in ARVD/C.

OBJECTIVE: To describe the extent and clinical significance of structural atrial involvement and atrial arrhythmias (AA) in ARVD/C stratified by genotype.

METHODS: We included 71 patients who met ARVD/C Task Force Criteria and underwent Cardiac Magnetic Resonance (CMR) imaging and molecular genetic analysis. Indexed atrial end-diastolic volume and area-length-ejection-fraction (ALEF) were evaluated on CMR and compared to controls with idiopathic right ventricular outflow tract tachycardia (n = 40). The primary outcome was occurrence of AA (atrial fibrillation or atrial flutter) during follow-up, recorded by 12-lead ECG, Holter monitoring or implantable cardioverter defibrillator (ICD) interrogation.

RESULTS: Patients harbored a desmosomal Plakophilin-2 (PKP2)(n = 37) or non-desmosomal Phospholamban (PLN) (n = 14) mutation. In 20 subjects, no pathogenic mutation was identified. Compared to controls, right atrial (RA) volumes were reduced in PKP2 (p = 0.002) and comparable in PLN (p = 0.441) mutation carriers. In patients with no mutation identified, RA (p = 0.011) and left atrial (p = 0.034) volumes were increased. Bi-atrial ALEF showed no significant difference between the groups. AA were experienced by 27% of patients and occurred equally among PKP2 (30%) and no mutation identified patients (30%), but less among PLN mutation carriers (14%).

CONCLUSION: Genotype influences atrial volume and occurrence of AA in ARVD/C. While the incidence of AA is similar in PKP2 mutation carriers and patients with no mutation identified, PKP2 mutation carriers have significantly smaller atria. This suggests a different arrhythmogenic mechanism. This article is protected by copyright. All rights reserved.