Prosthesis-Patient Mismatch is Associated with Higher Operative Mortality Following Aortic Valve Replacement

Background

Prosthesis-patient mismatch (PPM) occurs when the valve prosthesis implanted at surgery is too small in relation to patient's body size, causing high transvalvular gradients. We investigated if severe PPM is related to early morbidity and mortality after aortic valve replacement (AVR).

Methods

We analysed prospectively collected data of 701 consecutive patients undergoing AVR between June 2001 and February 2006 at two Australian public hospitals. The indexed valve effective orifice area (IEOA) was estimated for each valve prosthesis implanted. PPM was defined as ≤0.65cm²m⁻². PPM was correlated with operative mortality, stroke, prolonged ventilation, new renal failure, prolonged intensive care stay, prolonged hospital stay and readmission to hospital within 30 days by univariate and multivariate methods.

Results

PPM was present in 6.6% of patients. Overall operative mortality was 4.1%. Isolated AVR was performed in only 38.4% of patients. For patients with PPM, the univariate and multivariate odds ratio for mortality were 5.2 (P=0.002) and 6.1 (P=0.006), respectively. The other multivariate predictors of mortality were age, pre-operative serum creatinine, emergency status, pulmonary artery pressure and bypass time. PPM was not associated with stroke, prolonged ventilation, new renal failure, prolonged intensive care or hospital stay, or readmission within 30 days.

Conclusion

PPM was associated with increased operative mortality. PPM should be avoided where possible as it may reduce operative mortality following AVR.

Keywords: Cardiac surgery, Mortality, Aortic valve surgery, Heart valve prosthesis