Usefulness of early exercise testing after non-Q-wave myocardial infarction in predicting prognosis

Abstract

The value of an early symptom-limited maximal exercise test in predicting coronary anatomy, left ventricular ejection fraction and hemodynamics was assessed prospectively in 64 patients after an acute non-Q-wave myocardial infarction (MI). Exercise tests and cardiac catheterization were performed at a median of 6 and 7 days, respectively, after non-Q MI. Forty-one percent of the patients had a negative exercise test response (no angina, less than 1 mm of ST depression and normal blood pressure responses). Twenty-five percent had a positive response (1 to 1.9 mm of ST depression or angina); 34% had a “strongly positive” exercise test response (at least 2 mm of ST depression or abnormal blood pressure responses). A negative response predicted the absence of 3-vessel disease (at least 70% stenosis) or critical stenoses (at least 90% stenosis) involving major coronary arteries (negative predictive accuracy 92%), whereas a strongly positive response predicted their presence (positive predictive value 77%, specificity 88%). Cardiac index and mean pulmonary artery wedge pressure did not vary significantly among the 3 exercise groups, whereas left ventricular ejection fraction was slightly higher in the exercise test group with a positive response (p < 0.025). Thus, in patients who have had a non-Q MI, early exercise testing can be used to predict the extent and severity of coronary artery disease, and the decision to perform coronary angiography should be guided by the exercise test results.