Background Exercise testing is commonly performed in patients with hypertrophic cardiomyopathy (HCM) to evaluate blood pressure response, a conventional risk factor for sudden cardiac death. The 2011 ACCF/AHA guidelines state “the role of metabolic stress testing in the evaluation of patients with HCM remains to be decided, particularly with regard to clinical outcome.

Methods and results Between 1998 and 2010, 1,898 patients (age 47 ± 15 years, 67% male) with HCM underwent cardiopulmonary exercise testing (CPX). During a mean follow-up of 5.8 ± 4 years, 178 (9.4%) patients reached the primary endpoint of all-cause mortality or orthotropic heart transplant. Peak oxygen consumption, V˙O₂ (HR 0.91 95% CI 0.89–0.93, p < 0.001), ventilatory efficiency, V˙EV˙CO₂ (HR 1.08 95% CI 1.06–1.09), and ventilatory anaerobic threshold V˙AT (HR 0.88 95% CI 0.84–0.92) were predictors of the primary outcome. A progressively worse prognosis was associated with higher ventilatory class (Figure 1). V˙EV˙CO₂ was a good predictor of heart failure death or transplantation (HR 1.1 95% CI 1.07–1.14 p < 0.001) outcome but not sudden cardiac death (HR 1.01 95% CI 0.97–0.96 p = 0.54).

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Abstract 88 Figure 1

Kaplan Kaplan Meier plot showing survival rates in 1898 patients with HCM stratified by ventilatory class. Table shows population at risk at 5 year time points

Conclusions CPX provides important prognostic information in patients with HCM. Sub-maximal exercise parameters are potentially more useful than peak VO₂ alone. Patients with an enhanced ventilatory response have a substantially higher risk of death or transplantation.

Reference 1 Gersh, et al. JACC 2011;58(25):212–60