Exercise testing post-MI: still worthwhile in the interventional era.

Valeur et al. report findings from a substudy of the DANAMI-2 trial. The paper describes the prognostic importance of a pre-discharge maximal exercise test following acute myocardial infarction in the era of aggressive reperfusion treatment of ST-elevation myocardial infarction (STEMI). Exercise testing has been validated and adopted for risk stratification before discharge in patients with acute coronary syndromes for several years. In addition to providing important prognostic information, exercise testing has also been used to select high-risk patients with provocable myocardial ischaemia (MI) suitable for revascularization. A pre-discharge exercise test also has significant impact on the patient’s rehabilitation; information on exercise capacity may facilitate tailored physical activity at a safe level, to be continued when the patient is at home. Since its first introduction in the 1930s, stressing the heart by exercise testing has been an important routine investigation in known or suspected coronary artery disease. However, in the modern era of very aggressive interventional reperfusion strategies, exercise testing is somewhat out of fashion, and today only a minority of patients go through a pre-discharge exercise test after an episode of acute coronary disease. In addition, the emphasis has progressively shifted from the exercise capacity obtained during the test, towards signs of ischaemia (ST-segment changes). Thus, when an exercise test is performed the information obtained on the individual exercise capacity may be overlooked because of the emphasis on ischaemia. This may be unfortunate since the exercise capacity is a strong independent risk factor for both cardiovascular and other mortality. Initially demonstrated in healthy subjects, a recent study by Myers showed that also in a clinical patient population referred for exercise testing with and without coronary artery disease, the peak exercise capacity was the strongest predictor for death. In fact, exercise capacity seems to be the best single exercise variable for identifying patients with low risk for cardiac death post-MI, either pre-discharge or post-discharge. In a meta-analysis of pre-discharge risk stratification, post-MI markers of left ventricular dysfunction (such as exercise duration) were better predictors of adverse outcome than markers of ischaemia. The rehabilitation aspect of testing is often neglected and the angiogram is substituted as a marker of increased risk, with the perception that once the stenosis is fixed, the risk is gone. However, the prognostic importance of angiographic findings is often overestimated.