Comparison of the effect of verapamil and propranolol on response of coronary vasomotion to cold pressor test in symptomatic patients with hypertrophic cardiomyopathy.

Impaired endothelium-dependent vasodilatation of coronary resistance vessels has been demonstrated in patients with hypertrophic cardiomyopathy (HC). The aim of this study was to compare the effect of verapamil and propranolol on the response of diastolic coronary blood flow velocity (CBFV) and coronary vascular resistance index to the cold pressor test (CPT) in symptomatic HC patients. In 15 patients with HC, the CBFV was measured in the distal portion of the left anterior descending coronary artery using high-sensitivity transthoracic Doppler echocardiography. Peak diastolic CBFV and coronary vascular resistance index (calculated as ratio of mean aortic pressure/CBFV ratio) were measured at baseline and after CPT. Changes of these parameters induced by the CPT (expressed as percentage of baseline values) were compared after verapamil and propranolol treatment in a crossover study. The same measurements were obtained in nine healthy control subjects. CPT induced an increasing pattern of CBFV during verapamil therapy, which was absent in CPT after propranolol administration (10.1 +/- 5.6% vs. -0.9 +/- 4.1%, P < 0.01). In healthy controls CBFV increased in response to CPT more than in HC patients receiving verapamil or propranolol (23.1+/- 12.8% P < 0.01 and P < 0.05, respectively). The coronary vascular resistance index increased during the CPT significantly less on verapamil than on propranolol treatment (3.5 +/- 9.2% vs. 18.1 +/- 13.5%, P < 0.01). In healthy controls the coronary vascular resistance index decreased during CPT -4.5 +/- 8.5% (P < 0.05 vs. verapamil and P < 0.01 vs. propranolol). Verapamil improved the coronary vasomotor response to CPT in relation to propranolol. Verapamil blunted the increase of the coronary vascular resistance index to the CPT in comparison with its change at CPT after propranolol. Thus, coronary endothelial dysfunction in symptomatic HC patients may be partially reduced by verapamil in comparison with propranolol treatment.