Prosthesis-Patient Mismatch After Aortic Valve Replacement
Are there predictors of prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR), and is there an association between PPM and the risk of perioperative and overall mortality?
A literature search was performed using PubMed, EMBASE, Ovid, and Google Scholar for studies published between 1965 and 2014 for “patient prosthesis mismatch” or “prosthesis patient mismatch.” Articles were included if there was a direct comparison in outcomes between patients with any degree of PPM and no PPM. Articles were excluded if there were <20 patients in any group, or if any parameter other than indexed effective orifice area (EOA) was used to define PPM. The main outcomes of interest were perioperative mortality and overall mortality.
The search yielded 382 studies for inclusion. Of these, 58 articles were analyzed and their data extracted. A total of 40,381 patients were included (39,568 surgical AVR and 813 transcatheter AVR). Predictors of PPM were: older age, female sex, hypertension, diabetes, renal failure, larger body surface area (BSA), larger body mass index (BMI), and the utilization of a bioprosthesis. Perioperative mortality was increased in the setting of any degree of PPM (odds ratio [OR], 1.54; 95% confidence interval [CI], 1.25-1.91; p < 0.0001), including patients with either severe (OR, 2.57; 95% CI, 1.12-5.88; p = 0.03) or moderate PPM (OR, 1.57; 95% CI, 1.17-2.11; p = 0.003). Compared to moderate PPM, severe PPM showed a nonsignificant trend toward increased perioperative mortality (OR, 1.68; 95% CI, 0.89-3.14; p = 0.11). Subgroup analysis revealed that the impact of PPM on perioperative mortality was higher in studies in which mean patient age was <70 years (OR, 1.62; 95% CI, 1.67-1.92; p < 0.0001) and/or AVR with and without coronary artery bypass grafting (CABG) was included (as opposed to only isolated AVR; OR, 1.60; 95% CI, 1.25-2.04; p = 0.0003). When only studies with isolated AVR were assessed, there was no evident effect between PPM perioperative mortality (OR, 1.45; 95% CI, 0.93-2.26; p = 0.1). Overall mortality was associated with any degree of PPM (hazard ratio [HR], 1.26; 95% CI, 1.16-1.36; p < 0.0001) or with severe PPM (HR, 1.43; 95% CI, 1.14-1.80; p = 0.002), but not with moderate PPM (HR, 1.01; 95% CI, 0.95-1.08; p = 0.68); patients with severe PPM had increased overall mortality risk compared to patients with moderate PPM (HR, 1.33; 95% CI, 1.18-1.51; p < 0.0001). The impact of PPM was less pronounced in patients with larger BMI (>28 kg/m2) compared to those with lower BMI.
PPM increases perioperative and overall mortality proportionally to its severity. The authors concluded that strategies to prevent PPM should be implemented, especially among patients <70 years of age and/or undergoing concomitant CABG.
This meta-analysis found that both perioperative and overall mortality were increased among patients with PPM, and that the interaction between PPM and mortality was greatest among patients <70 years of age, in the setting of concomitant CABG at the time of AVR, and with BMI <28 kg/m2. Previous studies have demonstrated a strong mortality interaction between PPM and reduced left ventricular ejection fraction (LVEF). The risk of PPM can be estimated by calculating the predicted EOA (using in vivo reference values) indexed to BSA at the time of AVR (severe PPM, EOA index <0.65 cm2/m2; moderate PPM, EOA index <0.85 cm2/m2). Preventive strategies should be individualized according to the patient’s risk profile and the anticipated severity of PPM. Severe PPM should be avoided in every patient undergoing AVR, and preventive measures should be considered in patients with anticipated moderate PPM with additional risk factors including age <70 years, BMI <28 kg/m2, concomitant CABG, and/or reduced LVEF.
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