952-30 Left Ventricular Ejection Performance Improves Late After Aortic Valve Replacement in Patients with Aortic Stenosis and Reduced Ejection Fraction

Abstract

To assess the time course and magnitude of change in left ventricular (LV) wall stress and ejection performance indices, 24 patients undergoing aortic valve replacement (AVR) for aortic stenosis were prospectively evaluated. Each patient underwent resting radionuclide angiography (RNA), echocardiography, and cardiac catheterization (high fidelity pressure) before AVR, then RNA and echocardiogram at one week and six months after AVR. Patients were stratified by preoperative ejection fraction (EF) into reduced EF (<50%) and normal EF (≥50%) groups. Pre-operatively, peak positive dp/dt was lower in the reduced EF group (1300 vs 1700 mmHg/sec, p = 0.035), and wall stress was elevated similarly in both groups (p = NS). Temporal Relationships of EF and Wall Stress Pre-op 1 Week 6 Mos Normal EF (n = 14) Mean Ejection Fraction (%) 66 64 68 Mean Wall Stress (dyne/cm 2 × 10 3 ) 62 34 44 Reduced EF (n = 10) Mean Ejection Fraction (%) 38 37 57 Mean Wall Stress (dyne/cm 2 × 10 3 ) 78 52 61 Wall stress was reduced at one week post-operatively (p < 0.005) in both groups. Ejection fraction remained depressed in the reduced EF group. By six months, however, EF had dramatically improved in the reduced EF group (p = 0.002). In patients with LV dysfunction, EF remains low one week after AVR despite rectification of afterload mismatch. At six months, however, ejection performance improves. Therefore, when measured by ejection phase indices, the surgical benefit from AVR is not evident until late post-operatively.