P310 CARDIOPULMONARY EXERCISE TEST IN THE EVALUATION OF A PATIENT WITH HFREF: THE IMPORTANCE IN THE ANALYSIS OF GAS KINETICS

Abstract

Abstract Introduction exertional dyspnea is a symptom present in several diseases, identifying the origin is of fundamental diagnostic and therapeutic importance. Cardiorespiratory exercise testing (CPET) is a valuable tool not only to assess functional capacity but also for diagnostic and prognostic purposes. Clinical case 55–year–old patient with a history of episode of acute pulmonary edema. Echocardiogram showed FE 35% with diffuse left ventricular (LV) hypokinesis and mild–to–moderate mitral insufficiency (MI). Diagnostic coronarography showed lesion–free coronary tree. An interrupted CPET at 140W showed peak O2 consumption of 23.6 mL/kg/min that excluded indication for cardiac transplantation. An echocardiogram from us confirmed dilated cardiomyopathy (CMPD) with FE=32%, diffuse VS hypokinesia and mild–to–moderate functional MI. CPET was repeated, maximal for respiratory quotient (1.42) interrupted due to muscle exhaustion, indicative of moderate reduction in functional capacity with peak VO2 at 64% of predicted, preserved anaerobic threshold at 51% of VO2 max and reduced VO2/W and Pulse Oxygen Ratio (VO2/HR) values from cardiogenic limitation. Also evident drop in VO2/HR during the final stages of the test and associated change in slope of the VO2/Work relationship a sign of decline in stroke volume and cardiogenic efficiency. Absent signs of ventilatory limitation, pulmonary vascular (Ve/VCO2=20.8 in normal range), or exercise desaturation. In the final phase of the test increase in VCO2 and Ve/VCO2 and Ve/VO2 equivalents. In order to find the explanation to the data collected by CPET, exercise echocardiogram was performed, which revealed the development of severe mitral valvular insufficiency and subsequent pulmonary hypertension justifying the behavior of the parameters collected by CPET. Discussion The oxygen pulse represents a metabolic surrogate for stroke volume. Normally during the active phases of exertion there is a progressive increase followed by a plateau. The evident flattening of the VO2/Work curve during the final phases of exercise and the concomitant decrease in oxygen pulse denote inadequate cardiac performance relative to the increased energy demands during exercise. Conclusions CPET proves to be a valuable clinical tool to guide the diagnostic–therapeutic pathway, particularly in the presence of complex heart disease (CMPD or IM).