Effects of patient-prosthesis mismatch on postoperative early mortality in isolated aortic stenosis

Small valve size and patient-prosthesis mismatch (PPM) generate high postoperative transvalvular gradients and may decrease both early and long-term survival. The study aim was to evaluate whether mismatch affected early mortality after aortic valve replacement (AVR) for isolated aortic stenosis (AS).

A total of 701 patients (437 males, 264 females; mean age 53.3 +/- 15.1 years; range: 14-84 years) with pure AS underwent AVR at the authors' institution between 1985 and 2005. The majority of patients (92%) received a mechanical valve. PPM was considered severe if the indexed effective orifice area was < or =0.65 cm2/m2, and moderate if > 0.65 but < or = 0.85 cm2/m2.

Moderate-severe PPM was present in 47% of patients, and severe PPM in 13%. The early mortality was 5.4% (n=38). Multivariate analysis revealed age > or = 70 years (p < 0.001), female gender (p = 0.04) and severe PPM (p = 0.003) as independent predictors of early mortality. Moderate mismatch was not a predictor of early mortality on both univariate and multivariate analysis. Left ventricular dysfunction (ejection fraction < or = 40%) was a risk factor for early mortality only in patients with severe PPM.

Patient-prosthesis mismatch should be prevented in patients undergoing AVR for isolated AS, especially in those with left ventricular dysfunction.