Abstract 2287: Prosthesis-Patient Mismatch is an Independent Predictor of Short-Term Mortality Following Mitral Valve Replacement

Abstract

Recent studies have shown that prosthesis-patient mismatch (PPM) is associated with an increased incidence of pulmonary hypertension and congestive heart failure and with reduced long-term survival following mitral valve replacement (MVR). The objective of this study was to examine the effect of PPM on operative mortality following MVR. The indexed valve effective orifice area (EOA) was estimated for each type and size of prosthesis being implanted in 1049 consecutive patients undergoing MVR±CABG and used to define PPM as not clinically significant if >1.2 cm 2 /m 2 , as moderate if >0.9 cm 2 /m 2 and ≤1.2 cm 2 /m 2 and as severe if ≤0.9 cm 2 /m 2 . Moderate PPM was present in 56% of patients and severe PPM in 12%. The overall operative mortality (OM) was 7% (n=73) and 84% were from cardiac causes (n=61, 6% of the whole cohort). Patients with severe PPM had higher overall OM (14%, p=0.0003) as well as operative cardiac-related death (CRD) (12%, p=0.007) than patients with moderate (OM: 6%, CRD: 5%) or nonsignificant PPM (OM: 6%, CRD: 4%). On multivariate analysis, severe PPM was an independent predictor of overall OM (Odds-ratio [OR]= 2.6 [95% confidence interval (CI): 1.3– 4.8], p=0.0045) and of operative CRD (OR= 2.3 [95%CI: 1.1– 4.4], p=0.02). Among the subset of 703 patients undergoing isolated MVR (i.e. without concomitant CABG), patients with severe PPM also had higher overall OM (12%, p=0.0025) than patients with moderate (4%) or nonsignificant PPM (3%). Mitral PPM was also a powerful independent predictor of both overall OM (OR=4.8, 95%CI: 1.8 –12.1, p=0.0009) and operative CRD (OR=3.2, 95%CI: 1.03– 8.7, p=0.03) in this subset of patients. Severe PPM is a strong independent predictor of both overall operative mortality and cardiac-related death after MVR. Hence, the projected indexed EOA should be systematically calculated at the time of operation prior to prosthesis implantation and an effort should be made to implant prosthesis with a larger EOA in patients who are identified as being at risk of severe PPM