PRKAG2 Syndrome: Clinical Features, Imaging Findings and Cardiac Events

Background/Objectives: PRKAG2 syndrome (PS) is a rare genocopy of hypertrophic cardiomyopathy (HCM). Our goal was to expand knowledge about PS by analyzing patient clinical, imaging, and follow-up data. Methods: The study included carriers of likely pathogenic or pathogenic PRKAG2 variants identified in the years 2011-2022. Cardiac involvement was assessed by electrocardiography, echocardiography, cardiac magnetic resonance imaging, and endomyocardial biopsy (EMB). We recorded concomitant diseases and cardiac events, including the implantation of electronic cardiac devices, arrhythmia, heart failure (HF), and death. Results: Seven patients from four families (median age 43 years) with PRKAG2 variants: Phe293Leu, Val336Leu, Arg302Gln, and His530Arg were included. At the first evaluation, 3 carriers were in New York Heart Association (NYHA) functional class II-III, while the remaining were in NYHA class I. Left ventricular hypertrophy (LVH) was present in 5 patients; 2 had ventricular pre-excitation, one was in atrial flutter and pacemaker-dependent; 2 had bradycardia. Two female carriers had concomitant chronic renal disease. In the EMB of one of the patients, staining for glycogen deposits was positive. Furthermore, we provide a link between the Val336Leu PRKAG2 variant and autophagy identified on EMB. After a median follow-up of 13.1 years, 6 carriers had LVH, 3 required admission for HF, and 1 had sustained ventricular tachycardia with subsequent cardioverter defibrillator implantation, and despite this, died suddenly; there were two de novo pacemaker implantations due to symptomatic bradycardia. Conclusions: PR is a distinctive disorder with an early onset of arrhythmic events, often leading to HF.