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 vessel s has been demonstrated in patients with hypertrophic cardiomyopathy (HC). The aim of this study was to compare the effect of verapamil and propranolo l on the response of diastolic coronary blood flow velocity (CBFV) and coro nary vascular resistance index to the cold presser test (CPT) in symptomati c HC patients. In 15 patients with HC, the CBFV was measured in the distal portion of the left anterior descending coronary artery using high-sensitiv ity transthoracic Doppler echocardiography. Peak diastolic CBFV and coronar y vascular resistance index (calculated as ratio of mean aortic pressure/CB FV ratio) were measured at baseline and after CPT Changes of these paramete rs induced by the CPT (expressed as percentage of baseline values) mere com pared after verapamil and propranolol treatment in a crossover study. The s ame measurements were obtained in nine healthy control subjects. CPT induce d 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 i n HC patients receiving verapamil or propranolol (23.1 +/- 12.8% P < 0.01 a nd P < 0.05, respectively). The coronary vascular resistance index increase d during the CPT significantly less on verapamil than on propranolol treatm ent (3.5 +/- 9.2% vs. 18.1 +/- 13.5%, P < 0.01). In healthy controls the co ronary vascular resistance index decreased during CPT -4.5 +/- 8.5% (P < 0. 05 vs. verapamil and P < 0.01 vs. propranolol). Verapamil improved the coro nary vasomotor response to CPT in relation to propranolol. Verapamil blunte d the increase of the coronary vascular resistance index to the CPT in comp arison with its change at CPT after propranolol. Thus, coronary endothelial dysfunction in symptomatic HC patients may be partially reduced by verapam il in comparison with propranolol treatment.