ICD indication in hypertrophic cardiomyopathy: which algorithm to use?

Area of Science:

• Cardiology
• Electrophysiology
• Genetics

Background:

• Hypertrophic cardiomyopathy (HCM) is a primary genetic heart disease.
• Implantable cardioverter-defibrillators (ICDs) are used for sudden cardiac death (SCD) prevention in HCM.
• Current guidelines from the European Society of Cardiology (ESC) and American Heart Association (AHA) provide differing recommendations for ICD implantation.

Purpose of the Study:

• To evaluate the agreement in ICD indications for HCM patients based on 2014 ESC and 2020 AHA guidelines.
• To assess fragmented QRS (fQRS) as a predictor of cardiovascular outcomes in HCM.
• To analyze the accuracy of SCD risk stratification algorithms in guiding ICD therapy.

Main Methods:

• Retrospective cohort study of 81 HCM patients (≥16 years) from 2019-2021.
• Kappa coefficient used to assess agreement between ESC and AHA guidelines for ICD indication.
• Kaplan-Meier method for survival and incidence curves; fQRS presence analyzed.
• Exclusion criteria: secondary myocardiopathy, follow-up <1 year.

Main Results:

• fQRS identified in 44.4% of patients; no association with clinical parameters, echocardiography, fibrosis, or SCD risk.
• During 4.8±3.4 years follow-up, no SCD occurred, but 20.6% of ICD recipients received appropriate shocks.
• Shocks occurred in ESC low- to moderate-risk (3), moderate-risk (3), and AHA high-risk (4) patients.
• Overall guideline agreement was 64% (kappa=0.270, p=0.007); C-statistic showed no difference in appropriate shock incidence (p=0.644).

Conclusions:

• Sudden cardiac death risk stratification algorithms exhibit discrepancies in ICD indications for HCM.
• Current risk stratification algorithms demonstrate low accuracy in predicting appropriate ICD shocks.
• Fragmented QRS is not a reliable predictor of adverse cardiovascular outcomes in this HCM cohort.