Management of vasospastic angina at rest with continuous infusion of isosorbide dinitrate. A double crossover study in a coronary care unit.

Twelve patients were studied who had frequent transient ischemic episodes at rest with a variable degree of coronary atherosclerosis and vasospastic origin of angina as evidenced by good exercise tolerance and results of thallium-201 scintigraphy during angina at rest, ergonovine maleate provocative test and coronary angiography. With the aim of keeping a constant blood drug level, the trial consisted of a continuous intravenous infusion of isosorbide dinitrate (1.25 to 5.0 mg/hour) during two periods (T₁ and T₂) of 24 hours (four patients) or 12 hours (eight patients) alternating with two equal periods (P₁ and P₂) of infusion of saline solution with a double crossover design (T₁, P₁, T₂ and P₂).Continuous electrocardiographic monitoring revealed that the total number of transient ischemic attacks at rest characterized by S-T segment elevation (four patients), S-T depression (two patients) and either S-T depression or elevation (six patients), with or without pain, was 100, 104 and 91, respectively, during the introductory control period and during P₁ and P₂, but was reduced to 13 and 20, respectively, during periods T₁ and T₂ (P = 0.002). Transient ischemic attacks at rest were completely prevented during both T₁ and T₂ in four patients and during T₁ or T₂ in three patients, and were not abolished but significantly reduced in T₁ and T₂ in the other five patients. The reduction in ischemic attacks was similar for episodes characterized by S-T segment elevation or depression and with or without pain. Side effects were negligible. Therefore, infusion of isosorbide dinitrate appears to be a very effective treatment for patients with vasospastic angina at rest.