Verapamil improves the response of coronary vasomotion to cold pressor test in asymptomatic and mildly symptomatic patients with hypertrophic cardiomyopathy.

Impaired endothelium-dependent vasodilatation of coronary resistance vessels was previously demonstrated in patients with hypertrophic cardiomyopathy (HC). Therefore, we decided to assess the effect of verapamil administration on the response of diastolic coronary blood flow velocity (CBFV) and the coronary vascular resistance index to the cold pressor test in asymptomatic and mildly symptomatic HC patients. In 10 patients with nonobstructive HC, the CBFV was detected in the distal portion of the left anterior descending coronary artery using high-sensitivity transthoracic Doppler echocardiography. Peak diastolic CBFV, the velocity-time integral of diastolic CBF, and the coronary vascular resistance index (calculated as the mean aortic pressure/CBFV ratio) were measured at baseline and after the cold pressor test. The percentage changes from baseline to the cold pressor test of these parameters were compared before and after 1 month of verapamil therapy. Open-label verapamil changed the decrease in CBFV into an increase in response to the cold pressor test (from -4.1 +/- 6.4% to +11 +/- 10.9%, P < 0.01). A similar reversibility of changes in the velocity-time integral of CBF in response to the cold pressor test after verapamil therapy was observed (from -3.3 +/- 8.3% to +9.6 +/- 10.3%, P < 0.05). Verapamil reversed the response of coronary resistance vessels to the cold pressor test from a +12 +/- 9.8% increase to a -5.2 +/- 10.2% decrease in the coronary vascular resistance index (P < 0.01). We concluded that in asymptomatic and mildly symptomatic HC patients in response to the cold pressor test, treatment with open-label verapamil increased CBF parameters and decreased the coronary vascular resistance index. Verapamil reversed the abnormal vasoconstrictor to vasodilator response of coronary resistance vessels to the cold pressor test. The restoration of the vasodilator response to the cold pressor test by verapamil suggests the potential positive effect of verapamil on endothelium-dependent coronary vasodilation in HC patients. Thus, a randomized blinded trial is now required.