Progression of coronary atherosclerosis: Is coronary spasm related to progression?

A total of 239 patients undergoing serial coronary angiography with a concomitant ergonovine provocation test were studied between July 1974 and June 1987. The progression of coronary artery disease was evaluated in relation to risk factors, especially coronary artery spasm. Patients were classified into three groups: 1) new myocardial infarction group (39 patients); 2) progression without infarction group (90 patients); and 3) nonprogression group (110 patients). To assess how risk factors and coronary spasm are related to the occurrence of new myocardial infarction and progression without infarction, 11 variables in the three groups were examined: age, gender, the time interval between the studies, fasting blood sugar, systolic blood pressure, diastolic blood pressure, smoking, serum cholesterol, triglyceride, uric acid and a positive response to the ergonovine provocation test. Multiple regression analysis selected three independent predictors of progression without infarction: cholesterol (p < 0.01), systolic blood pressure (p < 0.05) and a positive response to the ergonovine provocation test (p < 0.001). Multiple regression analysis also selected three independent predictors of the occurrence of new myocardial infarction: fasting blood sugar (p < 0.01), systolic blood pressure (p < 0.05) and a positive response to the ergonovine provocation test (p < 0.001). A positive response to the ergonovine provocation test was the strongest factor for occurrence of both new myocardial infarction and progression without infarction. To evaluate segmental arterial changes, 3,275 coronary artery segments were analyzed in the 239 patients. Both new myocardial infarction and progression without infarction frequently occurred in the proximal segments of the right coronary artery, the proximal and middle segments of the left anterior descending artery and the middle segments of the circumflex coronary artery. Although occurrence of both new myocardial infarction and progression without infarction were often evident in coronary artery segments with severe narrowing, >50% of new myocardial infarctions occurred in relation to segments narrowed <50%. The study strongly suggests that coronary spasticity may play a significant role in progression of coronary artery disease and that usual risk factors are closely related to the disease progression. The study also demonstrates that patients with myocardial infarction often show a “jump-up” phenomenon in which a minimal coronary stenosis progresses to total obstruction.