Myocardial Scarring and SCD in Young HCM Patients

Oct 02, 2024
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Authors:
Chan RH, van der Wal L, Liberato G, et al.
Citation:
Myocardial Scarring and Sudden Cardiac Death in Young Patients With Hypertrophic Cardiomyopathy: A Multicenter Cohort Study. JAMA Cardiol 2024;Sep 25:[Epublished].
Summary By:
Supriya Shore, MD

Quick Takes

  • In a retrospective, multicenter cohort study of 700 HCM pediatric patients, LGE on cardiac MRI was associated with SCD independently.
  • LGE on cardiac MRI improved performance of validated SCD risk prediction scores for HCM in pediatric patients.
  • A larger burden of LGE on cardiac MRI portended a higher SCD risk supporting quantification of LGE in these patients.

Study Questions:

What is the association between late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (cMRI) and sudden cardiac death (SCD) in pediatric patients with hypertrophic cardiomyopathy (HCM), and does it add to pediatric SCD risk models?

Methods:

This retrospective, multicenter cohort study included patients under 21 years of age with HCM across 37 international sites who had cMRI. Patients with nonsarcomeric HCM were excluded. The primary outcome was SCD, defined as unexpected death within 1 hour of symptom onset in patients with previously stable or uneventful clinical course.

Results:

This study included 700 patients with a mean age of 12 years at diagnosis and 15 years at cMRI and included 26% females; 5% experienced SCD. Biventricular systolic function was normal in all patients and 24% had left ventricular (LV) outflow tract obstruction. On average, left atrial (LA) size was normal, and no patient had apical aneurysm. Overall, 33% of patients had LGE, and these patients were older with a higher LV mass, higher wall thickness, and a larger LA diameter. Unadjusted analysis showed that LGE correlated with an increased SCD risk (hazard ratio, 4.46; 95% confidence interval, 2.16-9.20). However, LGE limited to right ventricular insertion point did not correlate with SCD risk. Patients with 10% more LGE relative to total myocardium had a higher SCD risk. After adjustment for SCD risk models in pediatric patients (AHA/ACC, ESC tools, HCM Risk-Kids, and PRIMaCY [Precision Medicine in Cardiomyopathy] score tools), LGE remained associated with SCD risk independently. Patients with SCD were more likely to harbor a pathogenic variant on genetic testing and pathogenic variants were more likely associated with LGE.

Conclusions:

In a retrospective analysis of a pediatric HCM cohort, LGE on cMRI was associated with SCD risk. Addition of LGE on cMRI to current risk SCD stratification tools improved their performance.

Perspective:

Identifying the risk of SCD in the pediatric HCM population poses several challenges. Pediatric patients have a higher risk for device-related complications due to longer exposure to lifetime risk, and these devices can be lifestyle-limiting. In addition, misclassification can result in premature death, which can be avoided. While LGE on cMRI has been validated as a risk predictor for SCD in adults with HCM, studies in pediatric HCM patients are lacking. This study establishes LGE as a risk predictor in pediatric HCM patients and also demonstrates that increasing LGE burden increased SCD risk. Most importantly, it improved the performance of validated risk prediction scores for pediatric HCM patients. These data support quantitative measures of LGE on cMRI in risk stratification for SCD in pediatric HCM patients.

Clinical Topics: Arrhythmias and Clinical EP, SCD/Ventricular Arrhythmias, CHD and Pediatrics and Arrhythmias, Heart Failure and Cardiomyopathies

Keywords: Death, Sudden, Cardiac, Hypertrophic Cardiomyopathy, Pediatrics


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