Exercise Hemodynamics After Aortic Valve Replacement for Severe Aortic Stenosis

Abstract

Severe aortic stenosis (AS) is often accompanied by diastolic dysfunction. After aortic valve replacement (AVR), the left ventricle often undergoes considerable reverse remodeling. Despite this, diastolic dysfunction may persist after AVR. The aims of this study were to determine the incidence of elevated left ventricular (LV) filling pressure at rest and during exercise among patients with severe AS after AVR and to describe factors related to elevated LV filling pressure, especially its association with LV and left atrial remodeling and myocardial fibrosis. Thirty-seven patients undergoing AVR were included. Echocardiography, cardiac computed tomography, and magnetic resonance imaging were performed before AVR. An LV biopsy sample was obtained during AVR and analyzed for collagen fraction. One year after AVR, right heart catheterization with exercise was performed. A mean pulmonary capillary wedge pressure (PCWP)≥28mm Hg during exercise was considered elevated. Twelve patients (32%) had elevated exercise PCWP 1year after AVR. Exercise PCWP was highest among patients undergoing concomitant coronary artery bypass graft surgery (30±7 vs 25±6mm Hg, P=.04) and among patients with preoperative stroke volume index<35mL/m2 (28±8 vs 23±4mm Hg, P<.05). Baseline LV ejection fraction was lower among patients with elevated PCWP (56±8% vs 64±8%, P=.01), and coronary calcium score was significantly higher (median 870 AU [interquartile range, 454-2,491 AU] vs 179 AU [interquartile range, 63-513 AU], P=.02). Conversely, exercise PCWP was not related to the presence of high LV wall mass or to the severity of AS. Among patients undergoing isolated AVR, there was a correlation between LV interstitial volume fraction and PCWP (r=0.57, P=.01) and mean pulmonary artery pressure (r=0.51, P=.03) during exercise. Elevated filling pressure during exercise was seen in one third of patients after AVR in this population and was seen primarily among patients with coexisting ischemic heart disease or diffuse myocardial fibrosis but was unrelated to preoperative severity of AS and LV remodeling.