Role of cardiopulmonary exercise testing in today's cardiovascular prevention and rehabilitation

In daily clinical practice when decisions are made about the value of exercise testing in patients with cardiovascular disease, the focus is inevitably on measures that reflect the state of the coronary arterial circulation, owing to the potential requirement for coronary angiography and revascularization. Hence, exercise capacity is typically brought into play in the context in which ischemic responses are interpreted: ischemia in the setting of poor exercise capacity means high risk, whereas in the setting of good exercise capacity it has little prognostic impact [1]. Conversely, although clinicians have long been aware that high levels of exercise capacity are associated with a better prognosis [2], the widespread tendency to ignore exercise capacity in clinical management seems to be linked to a general uncertainty about the therapeutic implications of exercise capacity. Exercise capacity can be of therapeutic value in two ways. As a non-modifiable indicator of risk, it can direct us to higher-risk patients who need a more intensified management: the benefits of coronary artery bypass graft (CABG) seem to be confined to those coronary artery disease (CAD) patients with impaired exercise capacity, even among patients with left ventricular systolic dysfunction [3]; and, in patients referred for rehabilitation after myocardial infarction, CABG or chronic ischemic heart disease, peak oxygen consumption (peak Vo2) is selected as the most important independent predictor of both cardiac and all-cause deaths, adjusted for confounding factors such as age, diabetes, continuing smoking, exertional hypotension, ST-segment depression, exercise-induced arrhythmias and various cardioactive drugs [4, 5]. As a modifiable risk factor, poor exercise capacity can specifically indicate the need to improve functional tolerance through exercise training. Even modest gains in cardiorespiratory fitness (+ 1 ml/kg per min of peak Vo2) can translate into a substantial lowering of cardiac mortality (9–10%) in both female and male CAD patients [4, 5] and, in selected stable CAD patients with mild exercise-induced symptoms and preserved left ventricular systolic function, a 12-month program of exercise training is associated with a significant increase in peak Vo2 and results in superior event-free survival compared to percutaneous coronary intervention [6].