August 14, 2019
2 min read

Novel risk model may predict sudden cardiac death in pediatric hypertrophic cardiomyopathy

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A novel risk stratification model estimated the risk for sudden cardiac death at 5 years in children with hypertrophic cardiomyopathy, according to a study published in JAMA Cardiology.

“The individualized estimates of risk should help clinicians to identify patients at highest risk and balance the risk of an arrhythmic event with prophylactic [implantable cardioverter defibrillator] implantation on conjunction with the patient and their parents or guardians,” Gabrielle Norrish, BMBCh, of the Centre for Inherited Cardiovascular Diseases at Great Ormond Street Hospital in London, the Institute of Cardiovascular Sciences at University College London and the European Reference Network for Rare and Complex Diseases of the Heart in Amsterdam, and colleagues wrote.

Children with hypertrophic cardiomyopathy

Researchers analyzed data from 1,024 children (mean age, 11 years; 68% boys) with hypertrophic cardiomyopathy who were evaluated between 1970 and 2017. Clinical data that were collected at baseline evaluations included disease cause, demographics, pedigree analysis, HF symptoms, 12-lead ECGs and echocardiograms. Patients underwent clinical reviews every 6 to 18 months.

Researchers also performed a systematic review of literature to identify sudden cardiac death risk factors as predictor variables in the risk model: NYHA/Ross functional class, nonsustained ventricular tachycardia, unexplained syncope, left atrial diameter z score, maximal wall thickness z score and maximal left ventricular outflow tract gradient.

The primary endpoint was a composite outcome of sudden cardiac death or an equivalent event including sustained ventricular tachycardia associated with hemodynamic compromise, appropriate ICD therapy or aborted cardiac arrest.

During a median follow-up of 5.3 years, 8.7% of patients suddenly died or had an equivalent event (annual event rate = 1.49; 95% CI, 1.15-1.92).

The model to predict the risk for sudden cardiac death had a C statistic of 0.69 (95% CI, 0.66-0.72) and a calibration slope of 0.98 (95% CI, 0.59-1.38).

One patient may be saved from sudden cardiac death at 5 years for every 10 ICDs that were implanted on those with a 5-year sudden cardiac death risk of at least 6%.

“External validation studies are now required to demonstrate the accuracy of this model’s predictions in diverse patient populations,” Norrish and colleagues wrote. “Consensus opinion of experts will be required to determine whether absolute thresholds for ICD recommendations are needed and, if so, where those thresholds should be set. Further refinement of this model could be achieved by including novel clinical risk predictors, such as cardiac magnetic resonance imaging and genetic data.”

Work in progress

“As with many first-generation risk tools, a less-than-perfect risk score incites future iterations — this is exactly our hope,” Robert O. Bonow, MD, MS, vice chair for development and innovation in the department of medicine, Max and Lilly Goldberg Distinguished Professor of Cardiology and professor of medicine (cardiology) at Northwestern University Feinberg School of Medicine and editor of JAMA Cardiology, and Elizabeth M. McNally, MD, PhD, director of the Center for Genetic Medicine, Elizabeth J. Ward Professor of Genetic Medicine and professor of medicine (cardiology) and of biochemistry and molecular genetics at Northwestern University Feinberg School of Medicine and associate editor of JAMA Cardiology, wrote in a related editor’s note. “The importance of a sudden death risk calculator for children with [hypertrophic cardiomyopathy] is clear and is of great public health benefit, but this risk score should be viewed as a work in progress.” – by Darlene Dobkowski

Disclosures: Norrish and Bonow report no relevant financial disclosures. McNally reports she received grants from the NIH and the U.S. Department of Defense and personal fees from AstraZeneca, Cytokinetics, Exonics Therapeutics, Invitae and Tenaya Therapeutics. Please see the study for all other authors’ relevant financial disclosures.