Myocardial contractile reserve: a global approach by combining cardiopulmonary exercise test with exercise-echocardiography

Abstract

Purpose: Several approaches are available to evaluate myocardial contractile reserve during exercise. Cardiopulmonary exercise test (CPET) allows a response characterization by well established variables with powerful prognostic power. Echocardiography allows for peak cardiac power output (CPO= mean BP x (SV/60) x HR) calculation, by incorporating flow measurement with blood pressure, which has been proposed as an index of energy imparted by the left ventricle (LV) to the volume of blood ejected per second. We aimed to explore if peak CPO reflects functional capacity as evaluated by CPET. Methods: 66 patients (mean age 64±11; male 81%) with different cardiovascular disease (HFrEF 59%, HFpEF 41%, aortic and mitral valvular disease 7.4%, aortic valvular disease 14.9%, mitral valvular disease 23.9%) in NYHA class II (50%), III (42%) and IV (8%) and mean EF of 51±16% were evaluated at rest and during incremental exercise (tiltable cycle ergometer) assessing peak CPO, peak VO2, VO2% of predicted peak and peak O2 pulse. Results: A good linear correlation was found between peak CPO and peak VO2, % of predicted peak VO2 and peak O2 pulse (Sperman's rho respectively of 0.619, 0.547 and 0.49, p <0,0001). The correlation was maintained along all the spectrum of LV systolic function at rest (see the figure), being patients with reduced EF (n 27) distributed on the left side of the regression due to the reduced contractile reserve. ![Figure][1] Conclusions: CPET indices of functional capacity showed a good correlation with echo-derived peak CPO, both in normal and reduced LV systolic function. These results confirm the potential prognostic role of such echocardiographic index and suggest the importance of systematically assess peak CPO during stress echocardiography. [1]: pending:yes