Abstract 4367215: Beyond the Apex: Redefining High-Risk Phenotypes in Apical Hypertrophic Cardiomyopathy

Background: Apical hypertrophic cardiomyopathy (ApHCM) with left ventricular apical aneurysm represents a newly recognized high-risk phenotype. The 2020 AHA/ACC guidelines established apical aneurysm as a class IIa indication for implantable cardioverter-defibrillator (ICD) placement, yet optimal risk stratification combining traditional markers with advanced imaging remains challenging. This variant carries significant implications for sudden cardiac death risk when multiple high-risk features converge. Case Presentation: We present a 61-year-old previously healthy male with recurrent syncope. Results from extended ambulatory monitoring revealed non-sustained ventricular tachycardia (NSVT). Echocardiography demonstrated apical wall hypertrophy with a 2.5 cm apical aneurysm and preserved ejection fraction of 60%. CMR confirmed ApHCM with quantitative LGE analysis revealing 18% of left ventricular mass involvement, predominantly outside right ventricular insertion points. The ESC 5-year sudden cardiac death risk score calculated at 2.8% (low-intermediate risk), yet convergence of three high-risk features—apical aneurysm, NSVT, and extensive LGE ≥15%—supported primary prevention ICD placement per 2020 AHA/ACC guidelines. Genetic testing revealed a variant of uncertain significance in MYBPC3. The patient underwent uncomplicated dual-chamber ICD implantation. At 6 month follow-up, patient remained asymptomatic with no syncope recurrence and no ICD therapies. Discussion: This case exemplifies the evolving paradigm in ApHCM risk stratification, demonstrating how advanced cardiac imaging can identify high-risk patients underestimated by traditional calculators. The convergence of apical aneurysm, NSVT, and extensive LGE represents a "triple threat" phenotype requiring aggressive primary prevention despite low calculated risk scores. Our case supports the 2020 AHA/ACC guideline inclusion of apical aneurysm as an established risk factor and highlights the critical role of quantitative LGE analysis. Future research should focus on developing ApHCM-specific risk calculators incorporating advanced imaging parameters to optimize patient selection for device therapy