Importance of newer cardiac magnetic resonance- based risk markers for sudden death prevention in hypertrophic cardiomyopathy: An international multicenter study

BACKGROUND The sudden death (SD) risk stratification algorithm in hypertrophic cardiomyopathy (HCM) has evolved, underscored recently by novel cardiac magnetic resonance (CMR)-based risk markers (left ventricular apical aneurysm, extensive late gadolinium enhancement, and end-stage disease with systolic dysfunction) incorporated into the 2020 American Heart Association (AHA)/ American College of Cardiology (ACC) HCM guidelines. OBJECTIVE The purpose of this study was to assess the specific impact of newer, predominantly CMR-based risk markers in a large multicenter HCM population that underwent primary prevention implantable cardioverter-defibrillator (ICD) implants. METHODS Longitudinal study of 1149 consecutive HCM patients from 6 North American and European HCM centers prospectively judged to be at high SD risk based on >= 1 AHA/ACC individual risk markers and prophylactically implanted with an ICD was performed. European Society of Cardiology (ESC) risk score was retrospectively analyzed with respect to the known clinical outcome. RESULTS Of 1149 patients with an ICD, 162 (14%) experienced device therapy terminating ventricular tachycardia/ventricular fibril-lation 4.6 +/- 4.2 years after implant. CMR-based markers solely or in combination led to ICD implantation in 49 of the 162 patients (30%) experiencing device therapy. Particularly low ESC scores (,4%/5 years) would have excluded an ESC ICD recommendation for 67 patients who nevertheless experienced appropriate ICD therapy, including 26 with the CMR-based risk markers not part of the ESC formula. CONCLUSION Identification and incorporation of novel guideline-supported CMR-based risk markers enhance selection of HCM patients for SD prevention with ICDs. Absence of CMR-based markers from the ESC risk score accounts, in part, for it not identifying many HCM patients with SD events. These data support inclusion of CMR as a routine part of HCM patient evaluation and risk stratification.