USEFULNESS OF EXERCISE TESTING SHORTLY AFTER ACUTE MYOCARDIAL-INFARCTION FOR PREDICTING 10-YEAR MORTALITY

Previous studies on tbe prognostic value of exercise test variables af ter acute myocardial infarction (AMI) are limited methodologically and have yielded inconsistent results. This study determined whether 6 ex ercise test variables (systolic blood pressure, ST-segment depression or elevation, exercise capacity, arrhythmias, and angina pectoris) aft er controlling for age and sex, enhance 6 clinical variables (digoxin, previous AMI, history of systemic hypertension and angina, Killip cla ss, and stress) as predictors of cardiovascular death and act as indep endent predictors as well. The present study followed 258 patients for 10.6 years, each of whom had AMI between 1977 and 1980 and an exercis e test before hospital discharge. By 1988, 71 of the 258 patients hats died, 56 of cardiovascular causes, This study is unique because expos ure and outcome variables are clearly defined and follow-up was comple te and longer than in previous studies. Multivariate survival analysis using an exponential model was tested to evaluate the conditional eff ects of the exercise test and clinical variables and to control for co nfounders. The model combined the exercise test and clinical variables . Results are reported with hazard ratios (HR) and 95% confidence inte rvals (CI). For important clinical risk predictors, tie HRs with Cls a re: digoxin use, HR 4.0 (CI 1.8, 8.5); history of prior AMI, HR 2.4 (C I 1.2, 4.7); history of systemic hypertension, HR 2.5 (CI 1.3, 4.5); a ngina, HR 2.4 (CI 1.3, 4.5); and stress, WR 4.2 (CI 2.2, 7.9). Three e xercise test variables hypotensive blood pressure response, HR 5.1 (CI 1.9, 13.6); ST-segment depression, HR 1.8 (CI 0.98, 3.6); and ST-segm ent elevation, HR 2.4 (CI 0.98, 5.9)-were strong independent predictor s of cardiovascular death after controlling: for age, sex, and clinica l variables. This is the only exercise test study with a complete 10.6 -year follow-up in the U.S., a clearly defined outcome, and showing th at 3 exercise test variables-hypotensive blood pressure response, and ST-segment depression and elevation-are strong independent predictors of cardiovascular death after controlling for clinical variables. Thes e results support the use of exercise testing after AMI for predicting long-term prognosis.