Aortic valve replacement for patients with mild to moderate aortic stenosis undergoing coronary artery bypass surgery

Abstract

Aortic valve replacement (AVR) is not normally recommended in asymptomatic patients, even if aortic stenosis is severe. However, as the population ages, an increasing number of patients with mild or moderate aortic stenosis will require coronary artery bypass grafting (CABG). In these cases, risk of "prophylactic" AVR needs to be weighed against risks of subsequent worsening of the mildly or moderately diseased aortic valve. If unoperated, aortic stenosis will worsen at an average of 6-8 mmHg per year (-0.1 cm2/year valve area), and one-quarter of such patients will require late AVR with a high operative mortality (14-24%). If AVR is performed at the time of CABG, operative risk is increased only slightly (from 1-3% to 2-6%), as are late mortality (1-2% per year) and morbidity (1-2% per year), mainly from hemorrhagic complications. Intrinsic gradients of most prosthetic valves are sufficiently low that even patients with low aortic valve gradients are likely to derive hemodynamic benefit from AVR. Thus, if there is a measurable (>20-25 mmHg) gradient across the aortic valve in a patient who requires CABG, the patient is at considerable risk for developing symptomatic aortic stenosis prior to reaching the end of expected benefit from CABG; in this case AVR should be considered. It may be reasonable in patients with very mild gradients (<25 mmHg) to defer aortic valve surgery; however, it should be noted that aortic stenosis progression is generally more rapid when the initial gradient is small.