Management of mild aortic stenosis at the time of coronary artery bypass surgery: should the valve be replaced?

Background: General consensus favors aortic valve replacement (AVR) for patients with moderate aortic stenosis (AS) undergoing coronary artery bypass graft surgery (CABG); however, the management of similar patients with mild AS is controversial. We therefore investigated such patients to determine incremental risk of concomitant AVR, progression of AS among those undergoing CABG alone, and operative risk of AVR after prior CABG.

Methods: Between January 1993 and December 2003, 316 consecutive patients with mild AS (mean gradient >15, <30 mm Hg) underwent CABG only (107) or CABG plus AVR (209). Follow-up was obtained by review of the medical record, the Social Security Death Index, and postal questionnaire.

Results: The operative mortality was 3.7% for CABG only and 4.3% for CABG plus AVR (p = 1). Survival at a mean of 5.4 +/- 3.6 years was similar. Multivariate predictors of late mortality included comorbid illnesses (Charlson comorbidity score and age-weighted summary of diseases; p = 0.001), small body surface area (p = 0.001), low ejection fraction (p = 0.007), preoperative permanent pacemaker (p = 0.04), and congestive heart failure (p = 0.046), but not AVR. Twenty-three CABG-only patients (21%) underwent subsequent AVR (mean 5.6 +/- 1.8 years) without mortality. Aortic valve replacement at the time of initial CABG (p <0.001) and older age (p = 0.02) were multivariate predictors of freedom from reoperation.

Conclusions: Prophylactic AVR for mild AS at CABG does not confer a survival benefit, and the likelihood of requiring AVR after CABG alone is low in the first 5 years. The decision to intervene on the valve is critically dependent upon the incremental operative risk imposed by concomitant AVR and late survival.