Untreated aortic valve stenosis identified at the time of coronary artery bypass grafting: thresholds associated with adverse prognosis.

OBJECTIVES

Aortic valve replacement (AVR) for severe aortic valve stenosis (AS) is a Class I indication at the time of coronary artery bypass grafting (CABG). Management of less-than-severe AS in patients undergoing CABG is uncertain however, because the thresholds at which untreated AS impacts long-term outcome are unclear.

METHODS

We identified 312 patients who underwent isolated CABG between 1993 and 2006 with mild or moderate AS [aortic valve area (AVA) 1-2 cm(2)], and matched them to patients undergoing CABG alone during the same period with similar characteristics but without AS (AVA >2 cm(2)). Long-term survival after CABG and its determinants were analysed using Cox proportional hazards models with AVR as a time-dependent covariate.

RESULTS

Late survival was lower in patients with untreated moderate AS (12 years 23 ± 5.1%) versus mild (42 ± 3.8%) or no AS (38 ± 3.3%) (P = 0.01). Adjusting for age, ejection fraction, heart failure, creatinine, diabetes, peripheral vascular disease (PVD) and interval AVR, moderate AS independently predicted higher mortality [hazard rate (HR) 2.01, 95% confidence interval (CI) 1.49-2.73; P < 0.001]; whereas incremental risk was insignificant for patients with mild AS (HR 1.09, 95% CI 0.85-1.66; P = 0.33). Further stratification showed that highest late postoperative mortality occurred with an AVA of 1-1.25 cm(2) (adjusted HR 2.45, 95% CI 1.57-3.82; P < 0.001), while risk was intermediate with an AVA of 1.25-1.5 cm(2) (HR 1.83, 95% CI 1.28-2.61; P = 0.001).

CONCLUSIONS

Untreated moderate AS is an independent determinant of excess late mortality following isolated CABG, and mortality risk increases with decreasing AVA. Those with moderate-to-severe AS (AVA 1-1.25 cm(2)) have more than 2-fold greater long-term mortality compared with those without AS. These data define AS severity thresholds for clinical trials aimed at defining whether valve intervention might mitigate this risk.