Value of maximal exercise tests in risk assessment of primary coronary heart disease events in healthy men: Five years' experience of the seattle heart watch study

Of 2,365 clinically healthy men who participated in the exercise testing unit of the Seattle Heart Watch, follow-up by annual mail questionnaires identified 47 persons (2 percent) who experienced primary coronary heart disease events. The mean follow-up period (± standard deviation) was 5.6 ±1.4 years. The rates of such events was higher in men 55 or more years of age than in the younger men. A count of the conventional risk factors identified at the time of initial examination was associated with increased 5 year probability of primary coronary heart disease events. However, univariate analysis of the individual risk factors (positive family history, hypertension, smoking, hypercholesterolemia) did not show a significant increase in 5 year probability.Four variables obtained from the response to symptom-limited maximal exercise testing were significantly associated with subsequent primary coronary heart disease events. These predictors were chest pain during maximal exertion, duration of exercise less than 6 minutes with the Bruce protocol, failure to attain at least 90 percent of the age-predicted maximal heart rate and ischémie S-T segment depression.When the conventional risk factors and the exercise predictors are both considered in asymptomatic men, maximal exercise testing identified a small group (1 percent of the total population) who had the highest 5 year probability of primary coronary heart disease (0.33). This group had one or more conventional risk factors and two or more exercise predictors identified. The probability in those with conventional risk factors but with less than two exercise predictors was 0.015. Forty-one percent of the population had no risk factors and the 5 year probability in this group was 0.01. Exercise testing was of no predictive value in the latter group.