Predictive Factors for Adverse Cardiac Events and Mortality in Patients with Hypertrophic Cardiomyopathy.

Background/Objectives: Risk stratification for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) remains challenging, especially in high-risk cohorts. This study evaluated the predictive utility of the ESC HCM Risk Score and the additive value of myocardial fibrosis assessment via cardiac magnetic resonance (CMR) in HCM patients with implantable cardioverter-defibrillators (ICDs) for primary prevention. Methods: A retrospective analysis was conducted on 108 HCM patients (mean age 49.4 ± 14.2 years; 30.6% female; 63.9% with LVOT obstruction) with ICDs for primary SCD prevention. The primary endpoint was a composite of all-cause mortality or appropriate ICD therapy for ventricular arrhythmia over a mean follow-up of 69.5 ± 22.8 months. ESC HCM Risk Scores, the presence of fibrosis on CMR, and clinical outcomes were analyzed using univariate and multivariate models, ROC curves, and Kaplan-Meier survival estimates. Results: The primary endpoint occurred in 25 patients (23.1%; 3.1%/year). An ESC HCM Risk Score ≥ 4% was common (81.5%) but did not significantly predict the primary outcome (the c-statistic 0.54; p = 0.08) and demonstrated low positive (25%) and high negative predictive values (85%). Severe fibrosis on CMR was significantly associated with events in univariate analysis (p = 0.04), and its inclusion improved the model's predictive accuracy (the c-statistic increased to 0.65; p = 0.03). Kaplan-Meier analysis revealed worse event-free survival in patients with both elevated ESC scores and more than mild fibrosis (p = 0.028). Conclusions: In this high-risk HCM cohort with ICDs, the ESC risk score showed limited predictive performance, while myocardial fibrosis on CMR added significant prognostic value. Incorporating the fibrosis assessment into future risk models may enhance SCD prediction and refine ICD decision-making in HCM. Further multicenter studies are needed to validate these findings.