Studies on ergometer exercise testing II. Effect of previous myocardial infarction, digoxin, and β‐blockade on exercise electrocardiography

The results of exercise electrocardiography were studied in a random sample of 317 subjects with clinical suspicion of coronary artery disease. In 278 patients with coronary artery disease the rate of false negative tests was 18% with and 12% without previous myocardial infarction. If ST elevation was considered a negative response, the corresponding values were 25% and 13%, respectively, p less than 0.01. The greatest prevalence of negative tests was seen after anterior myocardial infarction: 27% or 42% when ST elevation was not included into positive responses. The sensitivity of exercise-induced ST depression for the presence of multivessel disease was lower after anterior infarction (67%) than in other patients with previous infarction (86%), p less than 0.01. The corresponding specificities were 71% and 22%, respectively, p less than 0.005. If ST elevation was included into positive responses these differences were abolished. In subjects without myocardial infarction the sensitivity was 89% and specificity 43%. Digitalized patients had somewhat higher sensitivity in the exercise electrocardiogram than those without digoxin, 90% vs. 81% (p less than 0.05), but the difference was not seen with exclusion of ST elevation. The specificity was not influenced by digitalis. beta-blockade had no effect on the sensitivity or specificity, but the prevalence of postexercise ST evolution was lower with (11%) than without (30%) beta-blockade. The prevalence of slowly ascending ST depression was reduced by three factors: the presence of digitalis in patients without previous myocardial infarction, infarction itself, and the extent of coronary artery disease. We conclude that exercise electrocardiography has only a limited value in prediction of multivessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)