Cardiopulmonary exercise test in myocardial ischemia detection

Exercise electrocardiography has low sensitivity for detection of myocardial ischemia. However, when combined with cardiopulmonary exercise testing (CPEX), the sensitivity and specificity of ischemia detection improves significantly. CPEX offers unique advantages over imaging techniques in tricky situations such as balanced ischemia. Early abnormal oxygen uptake would point toward profound coronary stenosis that could be missed in perfusion imaging. CPEX could be an invaluable tool in asymptomatic left bundle branch block pattern, without exposing patients to the risks of computerized tomography or invasive coronary angiography. Normal oxygen uptake curves would rule out significant coronary stenosis as the cause of left bundle branch block pattern. Elseways, abnormal oxygen uptake in patients with normal coronary arteries could indicate microvascular angina. Furthermore, exercise capacity is an excellent predictor of cardiovascular risk in those with and without heart disease. Using two clinical cases we introduce the concept of gas-exchange and hemodynamic changes encountered in ischemic heart disease.