Effect of diltiazem on coronary flow reserve in patients with microvascular angina

Microvascular angina is characterized by ischemia-like symptoms in patients with normal coronary arteries and reduced coronary flow reserve. Clinical observations suggested an improvement in clinical symptomatology and exercise tolerance after treatment with calcium antagonists. The effect of diltiazem on coronary flow reserve was evaluated in controls and in patients with microvascular angina. Coronary flow reserve was measured in 16 normotensive patients (7 females, 9 males, mean age 51 ± 10 years) with angiographically normal coronary arteries. Coronary blood flow was determined at rest, after dipyridamole (0.5 mg/kg) and following intravenous administration of diltiazem (10 mg) using coronary sinus thermodilution technique. Coronary flow reserve was calculated as coronary blood flow after dipyridamole divided by coronary blood flow at rest. Patients with normal coronary flow reserve (coronary flow reserve >2.0) received either dipyridamole alone (group 1, controls, n = 6) or dipyridamole and diltiazem (group 2, n = 5), whereas patients with reduced coronary flow reserve (coronary flow reserve