The utility of cardiopulmonary exercise testing in the assessment of suspected microvascular ischemia

Abstract

Evidence demonstrating the potential value of cardiopulmonary exercise testing (CPET) to accurately detect myocardial ischemia secondary to macro-vascular disease is beginning to emerge. Despite distinct mechanisms mediating ischemia in micro-vascular and macrovascular coronary artery disease (CAD), the net physiologic effect of exercise-induced left ventricular (LV) dysfunction is common to both. The abnormal physiologic response to CPET may, therefore, be similar in patients with macro- and micro-vascular ischemia. The following case report describes the CPET abnormalities in a patient with suspected microvascular CAD and the subsequent improvement in LV function following three weeks of medical therapy with the anti-ischemic drug ranolazine.

Figure 1

AT: Anaerobic threshold, determined by the V-slope method VO₂: Oxygen uptake, milliliters per minute (ml/min) HR: Heart rate, beats per minute

Figure 2

O₂-Pulse: Oxygen Pulse, oxygen uptake (ml/min) divided by heart rate (beats per minute) O₂-pulse = Stroke volume X C(a-v)O₂