Cutaneous and coronary flow reserve in patients with microvascular angina

Microvascular angina is characterized by exercise-induced angina in patients with normal coronary arteries and reduced coronary flow reserve. Recently, a generalized disorder of abnormal vascular reactivity in microvascular angina has been postulated. Therefore, coronary flow reserve was determined by the coronary sinus thermodilution technique and compared with the cutaneous flux ratio in 6 control subjects (group 1) and 12 patients with microvascular angina (group 2). Coronary flow reserve was calculated from maximal coronary flow after 0.5 mg/kg of dipyridamole divided by flow at rest. Cutaneous flow ratio was estimated by laser Doppler fluxmetry (right forearm) before and after 4 min of suprasystolic blood pressure occlusion. Coronary flow at rest was identical in the two groups, but after maximal vasodilation with dipyridamole, coronary flow was higher in group 1 than in group 2 (p less than 0.05). Coronary flow reserve differed significantly between the two groups (2.9 in group 1 and 1.3 in group 2; p less than 0.001). Cutaneous Doppler flux at rest was higher in group 1 than in group 2 (p less than 0.05). However, the hyperemic response was identical in both groups. It is concluded that the cutaneous flux ratio in patients with microvascular angina is not impaired. Local peripheral vasomotor tone appears to be increased in patients with microvascular angina because cutaneous flow at rest is reduced. Thus, a generalized disorder of abnormal vascular reactivity cannot be confirmed in patients with microvascular angina.