Diagnostic Approach in Exercise Testing to Detect a Significant Narrowing of the Left Anterior Descending Coronary Artery in Inferior vs Posterior Myocardial Infarction

To detect a significant narrowing of the left anterior descending artery in patients with inferior/posterior myocardial infarction, 200 patients underwent standard exercise testing. Age, gender, and grade of stenosis of the left anterior descending artery were similar in 138 patients with inferior myocardial infarction and 62 with posterior myocardial infarction. In patients with left anterior descending artery stenosis, there were more lateral leads with ST-segment depression (1.8+/-1.0 vs 1.1+/-1.1; p<0.01) and fewer anterior leads with ST-segment depression (2.1+/-1.4 vs 2.9+/-1.4; p=0.02) in those with inferior myocardial infarction than in those with posterior myocardial infarction. Applying the criterion of exercise-induced ST-segment depression > or = 0.1 mV, sensitivities and specificities in detecting left anterior descending artery stenosis were 98% and 21% respectively in inferior myocardial infarction and 94% and 26% respectively in posterior myocardial infarction. In contrast, discriminant analysis revealed sensitivities and specificities of 77% and 91% respectively in inferior myocardial infarction and 71% and 81% respectively in posterior myocardial infarction using the variables related to severity of inducible ischemia and lateral and anterior lead ST-segment depression. These results indicate that a multivariate approach underscoring the site of myocardial infarction can help in identifying stenosis of the left anterior descending artery in patients with inferior/posterior myocardial infarction.