Value of Exercise Stress Echocardiography in Children with Hypertrophic Cardiomyopathy
El Assaad I, Gauvreau K, Rizwan R, Margossian R, Colan S, Chen MH.
J Am Soc Echocardiogr. 2020 Apr 9. pii: S0894-7317(20)30067-5. doi: 10.1016/j.echo.2020.01.020. [Epub ahead of print]
Take Home Points
- Exercise stress echocardiography (ESE) is a safe and feasible modality in children with hypertrophic cardiomyopathy.
- In children without rest LVOT gradient 44% develop gradients > 30 mm Hg with exercise.
- ESE-derived rest and exercise gradients correlated with risk of cardiac outcome.
- Children with LVOT gradients <30 mm Hg have lowest risk of CV events.
- Children with LVOT gradients ≥30 mm Hg have 5 times the risk of CV events.
Comment from Dr. Jennifer Johnson (Pittsburgh, PA), Section Editor of Pediatric Cardiology Journal Watch: This is a single center retrospective chart review of all pediatric hypertrophic cardiomyopathy patients who underwent exercise stress echocardiography to determine if exercise stress echocardiography can be useful in risk stratifying hypertrophic cardiomyopathy subgroups and if LVOT obstruction occurs in the patients with nonobstructive hypertrophic cardiomyopathy.
Methods: Data was collected on all pediatric hypertrophic cardiomyopathy patient who underwent exercise stress echocardiography from 2007-2018 at Boston Children’s Hospital. Subjects 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. The composite adverse endpoints on follow-up included heart transplant, aborted cardiac arrest, and sudden cardiac death.
Results: A total of 91 (61% male), median age 12 years (6-24 years) with hypertrophic cardiomyopathy underwent exercise stress echocardiography; baseline patient characteristics are described in table 1. Median left ventricle wall thickness was 20 mm and 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).
Exercise stress echocardiography data; table 2. Of the 40 patients in group 2 (resting LVOT <30 mmHg, exercise LVOT gradient ³ 30 mmHg) 20 had obstruction due to septal hypertrophy/systolic anterior motion, 13 patients mid cavitary obstruction and other 7 patients had a mixed obstruction etiology.
Of the total cohort, 73 (80%) subjects were free of cardiac events prior to the first exercise stress echocardiogram study. In the 3 year follow up data 26 patients had 31 cardiac events.
Discussion: In this cohort, 90 (99%) patients had an event-free exercise stress echocardiogram with one group 3 patient experiencing a fast-polymorphic ventricular fibrillation arrest requiring resuscitation during exercise stress test. This data showed pediatric exercise stress echocardiogram for hypertrophic cardiomyopathy can be performed safely with low risk to the patients.