Myocardial Scarring Increases Sudden Cardiac Death Risk in Young HCM Patients: JAMA

In the study, quantitative late gadolinium enhancement (LGE) emerged as a significant risk factor for SCD in patients under 21 years with hypertrophic cardiomyopathy, enhancing risk stratification efforts.

Hypertrophic cardiomyopathy, a genetic condition characterized by abnormal thickening of the heart muscle, is known to increase the risk of arrhythmias and sudden cardiac events. Currently, predicting SCD in children and adolescents with HCM is insufficient. In adults with HCM, late gadolinium enhancement observed through cardiovascular magnetic resonance (CMR) imaging has been linked to SCD events. In this context, Raymond H. Chan, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada, and colleagues aimed to investigate the prognostic significance of LGE in patients with HCM younger than 21 years.

For this purpose, a multicenter, retrospective cohort study was conducted from April 8, 2015, to September 12, 2022, involving patients under 21 years old with HCM who underwent CMR imaging across various sites in the US, Europe, and South America. Observers of the CMR studies were blinded to outcomes and demographic details. The study focused on the natural history of HCM, with the primary outcome being SCD and related events, such as resuscitated cardiac arrest and appropriate discharges from an implantable defibrillator.

Continuous and categorical data were presented as means (SD), medians (IQR), or counts (percentages). Kaplan-Meier curves were used to compare survivors with and without LGE, and the likelihood of subsequent clinical events was assessed using univariate and multivariable Cox proportional hazards models.

Results from the study involving 700 patients across 37 international centers showed a median age of 14.8 years, with 74% being male. Based on the study, the researchers reported the following findings:

The study led to the following findings:

• Over a median follow-up period of 1.9 years, 5% of patients experienced sudden cardiac death or related events.
• Late gadolinium enhancement was found in 33% of patients, averaging 5.9% of the left ventricular myocardium.
• There was a higher amount of LGE in older patients and those with greater left ventricular mass and wall thickness.
• Patients with LGE had lower left ventricular ejection fractions and larger left atrial diameters.
• The presence and extent of LGE were linked to SCD, even after adjusting for existing risk assessment tools. Specifically, patients with 10% or more LGE relative to total myocardium had a significantly higher risk of SCD (unadjusted hazard ratio of 2.19).
• Incorporating LGE burden improved the predictive accuracy of the HCM Risk-Kids score (from 0.66 to 0.73) and the Precision Medicine in Cardiomyopathy score (from 0.68 to 0.73) for SCD.

The authors found that late gadolinium enhancement significantly improved the classification of sudden cardiac risk in children, adolescents, and young adults with hypertrophic cardiomyopathy. They recommend that LGE be considered during the clinical evaluation of these patients.

Reference:

Chan RH, van der Wal L, Liberato G, et al. Myocardial Scarring and Sudden Cardiac Death in Young Patients With Hypertrophic Cardiomyopathy: A Multicenter Cohort Study. JAMA Cardiol. Published online September 25, 2024. doi:10.1001/jamacardio.2024.2824