Recombinant tissue-type plasminogen activator followed by heparin compared with heparin alone for refractory unstable angina pectoris

Narrowing or occlusion of the coronary arteries (which supply the heart) causes a decrease in the cardiac blood supply (myocardial ischemia) and can result in pain in the region of the heart (angina pectoris). This pain is exacerbated by exercise and stress. When the pain worsens, and begins to occur even during periods of rest, the condition is referred to as unstable angina. This development frequently precedes acute myocardial infarction (heart attack; an acute total blockage of one or more of the coronary arteries resulting, if not promptly treated, in permanent cardiac damage and even death). Unstable angina usually responds to treatment with vasodilator medications (which relax blood vessels), but a subset of patients do not improve with this therapy, and are at great risk of suffering a heart attack. Drugs that prevent clotting (such as heparin) and that dissolve existing blood clots (such as tissue-type plasminogen activator or streptokinase) may have beneficial effects in this group of high-risk patients. To investigate this theory, 24 vasodilator-resistant unstable angina patients were randomly assigned to receive either heparin alone or heparin plus recombinant tissue-type plasminogen activator (rt-PA). Recurrent ischemic attacks were documented in 9 of 12 patients who received heparin alone; none of the patients who were given rt-PA experienced these symptoms. Statistical modeling demonstrated that there was a significantly greater tendency among the rt-PA patients to remain symptom-free over time (up to three days). Quantitative coronary angiography (an X-ray technique for visualizing the coronary arteries) did not reveal any change in the size of ischemia-related heart lesions after either treatment. Treatment with rt-PA does not confer a permanent improvement in coronary artery status nor obviate the need for procedures which improve cardiac blood flow; however, rt-PA may allow these procedures to be performed in more optimal circumstances. (Consumer Summary produced by Reliance Medical Information, Inc.)