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

Abstract

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<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<0.01. The corresponding specificities were 71% and 22%, respectively, p<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<0.05), but the difference was not seen with exclusion of ST elevation. The specificity was not influenced by digitalis. β‐blockade had no effect on the sensitivity or specificity, but the prevalence of postexercise ST evolution was lower with (11%) than without (30%) β‐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. Digitalis and β‐blockade do not influence the sensitivity or specificity of exercise eletrocardiography, but digitalis modifies the type of ST‐segment response. Copyright © 1986 Wiley Periodicals, Inc.