Ergospirometry in the assessment of functional significance of myocardial ischemia

It has been shown that the ECG exercise stress test (ET) has low sensitivity and this limitation is successfully overcome by combinations with imaging techniques (stress echocardiography (ESE), nuclear medicine, magnetic resonance). Despite improved accuracy in the detection of myocardial ischemia and segmental wall motion analysis, these combinations cannot precisely determine the significance of functional impairment. Thus, the application of ergospirometry significantly improved the sensitivity of ECG ET. In addition to the fact that the most important parameters of CPET are peak myocardial oxygen consumption (PeakVO2) and assessment of ventilatory function, there are specific CPET markers. Significant myocardial ischemia (> 10% of the left ventricular myocardium i.e 3 segments) leads to significant dyssynergia (hypo or akinesia) inducing transient decrease in the ejection fraction. We can detect this point as a plateau (flattening) of the oxygen pulse (VO2/HR) as a consequence of decreased stroke volume and, also, the inadequate increase in VO2 despite the increase of the workload load. These markers appear after echocardiographic changes, and before ECG changes and chest pain on the ischemic cascade of events. We presented a case of a patient with complete left branch block and suspected coronary heart disease who showed typical changes on CPET, and a significant narrowing of LAD on coronary angiography. We used combined stress echocardiography with CPET (ESE-CPET) to confirm ischemia.