Metaboreflex-mediated hemodynamic abnormalities in individuals with coronary artery disease without overt signs or symptoms of heart failure

This study was devised to investigate the effect of coronary artery disease (CAD) without overt signs of heart failure on the cardiovascular responses to muscle metaboreflex activation. We hypothesized that any CAD-induced pre-clinical systolic and/or diastolic dysfunction could impair hemodynamic response to the metaboreflex test. Twelve males diagnosed with CAD without any sign or symptoms of heart failure and 11 age-matched healthy controls (CTL) participated in the study. Subjects performed a post-exercise muscle ischemia (PEMI) test to activate the metaboreflex. They also performed a control exercise-recovery test to compare data from the PEMI test. The main results were that the CAD group reached a similar mean arterial blood pressure (MAP) response as to the CTL during PEMI. However, the mechanism by which this response was achieved was different between groups. In particular, CAD achieved the target MAP by increasing systemic vascular resistance (+383.8±256.6 vs. +91.2±293.5 dynes·s-1·cm-5for the CAD and the CTL group respectively), CTL by increasing cardiac pre-load (-0.92±8.53 vs. 5.34±4.29 ml in end-diastolic volume for the CAD and the CTL group respectively), which led to an enhanced stroke volume and cardiac output. Furthermore, the ventricular filling rate response was higher in the CTL than in the CAD group during PEMI (p<0.05 for all comparisons). This study confirms that diastolic function is pivotal for normal hemodynamics during the metaboreflex. Moreover, it provides evidence that early signs of diastolic impairment due to CAD can be detected by the metaboreflex test.