Randomized Trial of Metoprolol in Patients with Obstructive Hypertrophic Cardiomyopathy

Background: The use of β-adrenergic receptor blocking agents in symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM) rests on clinical experience and observational cohort studies. Objectives: This study aimed to investigate the effects of metoprolol on left ventricular outflow tract (LVOT) obstruction, symptoms, and exercise capacity in patients with obstructive hypertrophic cardiomyopathy. In this double-blind, placebo-controlled, randomized crossover trial 29 patients with obstructive HCM and New York Heart Association (NYHA) functional class II or higher symptoms from May 2018 to September 2020 were enrolled. Patients received metoprolol or placebo for 2 consecutive 2-week periods in random order. The effect parameters were LVOT gradients, NYHA functional class, Canadian Cardiovascular Society (CCS) angina class, Kansas City Cardiomyopathy Questionnaire Overall Summary Score (KCCQ-OSS), and cardiopulmonary exercise testing. Results: Compared with placebo, the LVOT gradient during metoprolol was lower at rest (25 mm Hg vs 72 mm Hg [P = 0.007), at peak exercise it was 28 mm Hg vs 62 mm Hg [P < 0.001), and postexercise (45 mm Hg vs 115 mm Hg [P < 0.0001). During metoprolol treatment, 14% of patients were in NYHA functional class III or higher compared with 38% of patients receiving placebo (P < 0.01). Similarly, no patients were in Canadian Cardiovascular Society (CCS) angina class III or higher during metoprolol treatment compared with 10% during placebo treatment (P < 0.01). These findings were confirmed by higher Kansas City Cardiomyopathy Questionnaire Overall Summary Score during metoprolol treatment (P = 0.039). Measures of exercise capacity, peak oxygen consumption, and N-terminal pro-B-type natriuretic peptide did not differ between the study arms. Conclusions: Compared with placebo, metoprolol reduced LVOT obstruction at rest and during exercise, provided symptom relief, and improved quality of life in patients with obstructive hypertrophic cardiomyopathy, while Maximum exercise capacity remained unchanged. Disclaimer: Lupin makes no representation or warranty of any kind, expressed or implied, regarding the accuracy, adequacy, validity, reliability, availability, or completeness of any scientific information shared by the HCP on the ­­­STAR UPDATE podcast. You should not allow the contents of this to substitute for your own medical judgment, which you should exercise in evaluating the information on this website.