Prevalence and Prognostic Significance of Hypertrophic Cardiomyopathy Phenotype in PKP2-Mediated Arrhythmogenic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) affects an estimated 1:500 individuals and is largely considered to be a disease of the sarcomere. However, disease-causative genetic variants in PLN -encoded phospholamban and JPH2 -encoded junctophilin-2 cause HCM via perturbations in intracellular calcium handling (ICH). Given recent case reports describing asymmetric left ventricular hypertrophy (LVH) in patients with arrhythmogenic cardiomyopathy (ACM)-predisposing genetic variants in PKP2 -encoded plakophilin-2, a gene known to play a role in ICH, we sought to examine the prevalence and clinical impact of an HCM phenotype in PKP2-ACM patients. In this retrospective study, review of 771 genotype-positive ACM patients evaluated between 01/2015 and 04/2024 was used to identify those with a pathogenic/likely pathogenic (P/LP) variant in PKP2. Pertinent demographic, electrocardiographic, imaging and outcome data was extracted from the electronic medical record. HCM was defined by the presence of maximal end-diastolic wall thickness of >15 mm anywhere in the left ventricle. Advanced heart failure (HF) and major VA outcomes [sudden cardiac arrest (SCA), sustained VT, and appropriate implantable cardioverter-defibrillator (ICD) shocks] were analyzed. Collectively, an HCM phenotype was observed in 9 (7.8%) of the 115 P/LP variant-positive patients (mean age 38±36; 51 (44%) male, and 57 with a ACM phenotype). Of note sigmoid subtype HCM was noted in 8/9 (89%) and left ventricular outflow tract obstruction present in 7/9 (78%; mean gradient of 57±48 mmHg). In comparison to PKP2-ACM patients without HCM, PKP2-HCM patients with HCM were older and less likely to have a family history of any cardiomyopathy (Table). Interestingly, in the patients with a positive phenotype, non-sustained VT and major VA outcomes were less prevalent in the HCM patients (Table). Nearly 8% of individuals with a P/LP variant in PKP2 have a concomitant HCM phenotype. Whether this observation reflects abnormal calcium handling in the setting of PKP2 haploinsufficiency or selection bias in the setting of the combined prevalence of HCM (1:500) and PKP2 loss-of-function (1:695) requires further studies. [ABSTRACT FROM AUTHOR]