Natural history of unstable angina with medical or surgical therapy.

In order to establish the natural evolution of unstable angina under medical treatment and to determine the possible benefits of revascularization surgery, 113 patients were studied; 51 received medical treatment (24 with intermediate syndrome and 27 with progressive angina), and 62 others received surgical treatment (28 with intermediate syndrome and 34 with progressive angina). After a mean follow-up of 32 months, the mortality in the medically treated groups was 46 percent (11/24) with intermediate syndrome and 7 percent (2/27) with progressive angina (P less than 0.005), and the incidence of myocardial infarction was 38 percent (9/24) and 7 percent (2/27), respectively (P less than 0.01). Moreover, in comparing cases treated medically or surgically, the mortality was as follows: intermediate syndrome treated medically, 46 percent (11/24) vs 11 percent (3/28) in those treated surgically (P less than 0.005); and progressive angina treated medically, 7 percent (2/27) vs 9 percent (3/34) in those treated surgically (P = 0.85). The incidence of myocardial infarction was as follows: intermediate syndrome treated medically, 38 percent (9/24) vs 14 percent (4/28) in those treated surgically (P less than or equal to 0.056); and progressive angina treated medically, 7 percent (2/27) vs 12 percent (4/34) in those treated surgically (P greater than 0.55).