Metoprolol improves left ventricular longitudinal function at rest and during exercise in obstructive hypertrophic cardiomyopathy

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Abstract Background Hypertrophic cardiomyopathy (HCM) patients with outflow obstruction often experience symptoms of heart failure upon exertion. We aimed to characterize left ventricular (LV) systolic function by segmental and global longitudinal strain echocardiography, and to investigate changes in relation to exercise, and the effect of standard treatment with beta-blockers. Method Twenty-nine patients with obstructive HCM and New York Heart Association (NYHA) class ≥ II symptoms were enrolled in a double-blind, placebo-controlled, randomized crossover trial. Patients received metoprolol 150 mg or placebo for two consecutive two-week periods in random order. Echocardiographic assessment with speckle-tracking derived longitudinal strain (LS) was performed at rest and during peak exercise at the end of each treatment period. Segmental LS was calculated as the mean of the six apical, mid, and basal segments. Results During placebo treatment resting values of segmental LS showed an apical-basal difference of −10.3% (95% confidence interval (CI): −12.7 to −7.8; p<0.0001), with severely depressed values of the basal segment −9.3 (4.2) %. Treatment with metoprolol improved LS of the apical segment (−2.8%; 95% CI: −4.2 to −1.3; p<0.001) and mid segment (−1.1%; 95% CI: −2.0 to −0.3; p=0.007). The segmental improvement with metoprolol treatment was reflected in an increase in resting global LS (LV GLS) (−1.4%; 95% CI: −2.3 to −0.6; p<0.001). Peak exercise was associated with a reduction in LV GLS, yet the improvement in LV GLS during metoprolol was consistent upon exercise (−1.3%; 95% CI: −2.6 to −0.1; p=0.03). Conclusion Segmental LS of the LV in obstructive HCM showed an abnormal apical-basal difference. Exercise was associated with a reduction in LV GLS, illustrating an impaired myocardial functional reserve capacity. Metoprolol significantly improved LS of the apical and mid segments of the LV at rest and LV GLS during exercise. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Novo nordic foundation