Exercise echocardiography in asymptomatic HCM: exercise capacity, and not LV outflow tract gradient predicts long-term outcomes
Milind Y Desai, Aditya Bhonsale, Parag Patel, Peyman Naji, Nicholas G Smedira, Maran Thamilarasan, Bruce W Lytle, Harry M Lever, Milind Y Desai, Aditya Bhonsale, Parag Patel, Peyman Naji, Nicholas G Smedira, Maran Thamilarasan, Bruce W Lytle, Harry M Lever
Abstract
Objectives: This study sought to assess long-term outcomes in asymptomatic or minimally symptomatic patients with hypertrophic cardiomyopathy (HCM) who underwent exercise echocardiography, without invasive therapies for relief of left ventricular outflow tract (LVOT) obstruction.
Background: Many HCM patients present with LVOT obstruction, mitral regurgitation (MR), and diastolic dysfunction, often requiring invasive therapies for symptomatic relief. However, a significant proportion of truly asymptomatic patients can be closely monitored. In HCM patients, exercise echocardiography has been shown to be a useful assessment of functional capacity and risk stratification.
Methods: We included 426 HCM patients (44 ± 14 years; 78% men) undergoing exercise echocardiography, excluding hypertensive heart disease of elderly, ejection fraction <50% and invasive therapy (myectomy or alcohol ablation) during follow-up. Clinical, echocardiographic (LV thickness, LVOT gradient, and MR) and exercise variables (percent of age-sex predicted metabolic equivalents [METs] and heart rate recovery [HRR] at 1 min post-exercise) were recorded. A composite endpoint of death, appropriate internal defibrillator discharge, and admission for congestive heart failure was recorded.
Results: Patients were asymptomatic or minimally symptomatic on history, but 82% of patients achieved <100% of age-sex predicted METs, and 43% had ≥II+ post-stress MR. The mean LV septal thickness, post-exercise LVOT gradient, and HRR were 2.0 ± 0.5 cm, 62 ± 47 mm Hg, and 31 ± 14 beats/min, respectively. During a mean follow-up of 8.7 ± 3 years, there were 52 events (12%). Patients achieving >100% of age-sex predicted METs had 1% event rate versus 12% in those achieving <85%. On stepwise multivariate survival analysis, percent of age-sex predicted METs (hazard ratio [HR]: 0.76; 95% confidence interval [CI]: 0.64 to 0.90), abnormal HRR (HR: 0.89; 95% CI: 0.82 to 0.97), and atrial fibrillation (HR: 2.73; 95% CI: 1.30 to 5.74) (overall, p < 0.001) independently predicted outcomes.
Conclusions: In asymptomatic or minimally symptomatic HCM patients, exercise stress testing provides excellent risk stratification, with a low event rate in patients achieving >100% of predicted METs.
Keywords: AF; CHF; HCM; HR; HRR; ICD; LVOT; METs; MR; VT; atrial fibrillation; congestive heart failure; exercise echocardiography; hazard ratio; heart rate recovery; hypertrophic cardiomyopathy; implantable cardioverter-defibrillator; left ventricular outflow tract; metabolic equivalents; mitral regurgitation; outcomes; ventricular tachycardia.
Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Source: PubMed