Long-Term Outcomes of Pediatric-Onset Hypertrophic Cardiomyopathy

Study Questions:

What are the long-term outcomes of pediatric hypertrophic cardiomyopathy (HCM), and what risk factors are predictive of life-threatening arrhythmias in this population?

Methods:

A retrospective review was performed at two national cardiomyopathy referral centers in Italy. Patients were included if they were age 1-16 years at diagnosis. Patients with metabolic and syndromic disease were excluded. Patients were assessed on an at least yearly basis.

Results:

One hundred patients (65% male) with a median [interquartile range] age of 12.2 [7.3-14.1 years] were included in the analysis. New York Heart Association class II or greater were present in 42 patients at the time of diagnosis. Sarcomere gene testing was positive in 55 of 70 (79%) patients. Over a median follow-up period of 9.2 years, 24% of patients experienced cardiac events (1.9% per year), including 19 lethal arrhythmic events (LAEs) and 5 heart-failure related deaths. LAEs occurred at a mean [standard deviation] age of 23.1 [11.5] years. Risk of LAE was associated with symptoms at onset (hazard ratio [HR], 8.2; 95% confidence interval [CI], 1.5-68.4; p = 0.02) and troponin I or troponin T gene mutations (HR, 4.1; 95% CI, 0.9-36.5; p = 0.06). Adult HCM risk factors including syncope and extreme left ventricular hypertrophy were not predictive of LAEs in this population.

Conclusions:

The authors concluded that pediatric-onset HCM is associated with adverse outcomes related primarily due to arrhythmic events. Predictors of adverse events differ in this population as compared with adult populations.

Perspective:

This study assessed the long-term outcomes for patients diagnosed with HCM as children. The study demonstrates different risk factors for arrhythmic events in pediatric as opposed to adult-onset HCM. While the presence of symptoms at the time of diagnosis and troponin I or T mutations were predictive of poor outcomes, traditional adult risk factors of syncope or extreme left ventricular hypertrophy were not significant. The study supports the use of pediatric-specific risk factors when prognosticating in this patient population, as well as the importance of continued follow-up into adulthood given persistence of risk beyond adolescence.

Clinical Topics: Arrhythmias and Clinical EP, Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Implantable Devices, Genetic Arrhythmic Conditions, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Quality Improvement, Acute Heart Failure

Keywords: Adolescent, Arrhythmias, Cardiac, Cardiomyopathies, Cardiomyopathy, Hypertrophic, Genetics, Heart Defects, Congenital, Heart Failure, Hypertrophy, Left Ventricular, Outcome Assessment (Health Care), Pediatrics, Risk Factors, Sarcomeres, Syncope, Troponin I, Troponin T


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