Unmasking Pulsus Alternans In Patients With Heart Failure With Reduced Ejection Fraction. The Importance Of Upright Exercise

Abstract

<h3>Background</h3> : Pulsus alternans (PA), typically observed in a supine resting position, is a poor prognostic indicator among patients with heart failure with reduced ejection fraction (HFrEF). We tested the hypothesis that PA may not be present in the supine position, but only when upright. <h3>Methods</h3> : 27 patients with severe HFrEF completed invasive cardiopulmonary exercise testing (CPET) with Swan-Ganz and radial arterial catheters. Hemodynamics were recorded in supine and upright resting positions. During exercise on upright cycle ergometry, hemodynamics were collected at two submaximal levels of exercise below ventilatory threshold (Steady-States 1 and 2) and peak effort. Breath-by-breath gas-exchange parameters were measured by indirect calorimetry. <h3>Results</h3> : Baseline characteristics are displayed in <b>Table 1</b>. Twenty-one participants showed no evidence of PA in either supine or upright position. However, six participants were found to have PA when in an upright resting but not supine resting position (<b>Figure 1</b>). Exercise hemodynamics and gas exchange parameters are displayed in <b>Table 2</b>. Maximal oxygen uptake (VO₂Max) was severely reduced, the cardiac output response to exercise was blunted, and exertional cardiac filling pressures were abnormal in both groups. <h3>Conclusions</h3> : PA, a poor prognostic indicator, may manifest in an upright but not supine position among patients with HFrEF. As human beings are upright and bipedal, this novel finding reinforces the importance of upright exertional hemodynamic assessments to guide risk-stratification and management.