Value of Exercise Stress Echocardiography in Children with Hypertrophic Cardiomyopathy.

BACKGROUND: Exercise stress echocardiography (ESE) is a valuable diagnostic and prognostic tool in adults with hypertrophic cardiomyopathy (HCM). Inducible and resting left ventricular outflow tract gradients are important predictors of heart failure. However, there are minimal data on the utility of this modality in children.

METHODS: Retrospective review of all pediatric HCM patients who underwent ESE at Boston Children's Hospital (January 2007-June 2018) was carried out. Patients were assigned to one of three categories based on left ventricular outflow tract gradients: group 1: <30 mm Hg at rest and exercise; group 2: <30 mm Hg at rest and ≥30 mm Hg with exercise; and group 3: ≥ 30 mm Hg at rest and exercise. Records were reviewed for earliest occurrence of composite endpoint of any one of the following: cardiac syncope, chest pain, nonsustained and sustained ventricular tachycardia, aborted cardiac arrest, heart failure class ≥ II, or HCM-related death/transplantation.

RESULTS: A total of 91 children (67% males) with median age 12 years (6-24 years) at first ESE and median left ventricle wall thickness of 20 mm formed the cohort. Median follow-up duration was 3 years. During ESE, only one child experienced an event and was resuscitated. Of the 91 children, 25 were classified as group 1, 40 as group 2, and 26 as group 3. Twenty-six patients met the composite endpoint, including two heart transplant, one aborted cardiac arrest, and one sudden cardiac death. Group 3 patients had a 5 times higher risk of developing symptoms and/or serious clinical outcome at any age (hazard ratio = 5.18; 95% CI, [1.39-19.2]; P = .014). During our short follow-up time, group 2 patients had a higher risk of outcome, but this did not achieve statistical significance (hazard ratio = 1.95; 95% CI, [0.5-7.6]; P = .33).

CONCLUSIONS: In this large series of pediatric patients with HCM, ESE can be performed safely and served as an effective tool to identify the lowest risk patients for cardiac outcome.