Metoprolol Improves Left Ventricular Longitudinal Strain at Rest and during Exercise in Obstructive Hypertrophic Cardiomyopathy

Abstract

Patients with obstructive hypertrophic cardiomyopathy (HCM) often experience symptoms of heart failure upon exertion despite having normal left ventricular (LV) ejection fractions. Longitudinal strain (LS) may be a more sensitive marker of systolic dysfunction in patients with LV hypertrophy. The aims of this study were to characterize LV segmental LS and global LS (GLS) at rest and during exercise and to assess if first-line treatment with β-blockers improves LV systolic performance. Twenty-nine patients with obstructive HCM and New York Heart Association functional class≥II symptoms were enrolled in a double-blind, placebo-controlled, randomized crossover trial. Patients received metoprolol 150mg or placebo for two consecutive 2-week periods in random order. Echocardiographic assessment with speckle-tracking-derived LS was performed at rest and during peak exercise at the end of each treatment period. During placebo treatment, resting values of segmental LS showed an apical-basal difference of -10.3% (95% CI, -12.7% to -7.8%; P<.0001), with a severely abnormal value of the basal segment of -9.3±4.2%. Treatment with metoprolol was associated with more negative LS values of the apical segment (-2.8%; 95% CI, -4.2% to -1.3%; P<.001) and the mid segment (-1.1%; 95% CI, -2.0% to -0.3%; P=.007). During peak exercise there was a deterioration in LV GLS, but treatment with metoprolol was associated with more negative peak exercise LV GLS (-1.3 %; 95% CI, -2.6% to -0.1%; P=.03). Systolic performance assessed by LV GLS showed impaired values at rest and during exercise, with severely depressed values of the basal and mid segments. Treatment with metoprolol improved LV GLS upon exercise, indicating a beneficial effect of β-blocker treatment on LV systolic function.