What can we learn from exercise testing beyond the detection of myocardial ischemia?

Noninvasive cardiopulmonary exercise (CPX) testing has proven useful in the assessment of heart and lung disease, including cardiac and ventilatory reserves. CPX includes the monitoring of respiratory gas exchange, O2 uptake the CO2 production, together with minute ventilation and its components--tidal volume and respiratory rate--together with surveillance of electrocardiography and blood pressure during supervised, incremental exercise. Exercise responses in anaerobic threshold and/or maximal O2 uptake are used to grade functional capacity objectively and to predict cardiac reserve (exercise cardiac output), which grades the severity of chronic cardiac or circulatory failure. CPX also serves to distinguish primary cardiac from ventilatory-based exertional dyspnea.