Effects of recent and remote infarction on the predictive accuracy of the ST segment/heart rate slope

The exercise electrocardiographic ST segment/heart rate slope accurately identifies three vessel coronary disease in patients with stable angina, but the method is less accurate in predischarge testing after recent myocardial infarction. To assess the effect of both recent (less than 3 weeks) infarction and remote (greater than 8 weeks) Q wave infarction on the ST segment/heart rate slope, the predictive value of a slope greater than 6.0 microV/beat per min for the identification of three vessel coronary artery disease was evaluated in 113 patients. The 58 patients with stable angina, including 17 with remote Q wave myocardial infarction, were similar to the 55 patients with recent myocardial infarction with respect to age and peak exercise heart rate. In patients with stable angina and no prior Q wave myocardial infarction, an ST segment/heart rate slope greater than 6.0 had a sensitivity of 92% (11 of 12), a specificity of 97% (28 of 29) and a positive predictive value of 92% (11 of 12) for three vessel coronary artery disease. In patients with stable angina and remote Q wave infarction, sensitivity was 83% (5 of 6), specificity was 91% (10 of 11) and positive predictive value was 83% (5 of 6). After recent infarction, test specificity for three vessel disease was preserved at 95% (39 of 41), but test sensitivity was poor (3 of 8). This was confirmed by evaluation of six additional recent patients with infarction and three vessel disease. Among the combined group with recent infarction, test sensitivity for three vessel disease was only 29% (4 of 14), significantly lower than in patients with stable angina (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)