Mortality risk proportional to PPM severity in aortic value surgery

By Laura Cowen

Prosthesis-patient mismatch (PPM) during surgical aortic valve replacement (AVR) is associated with a perioperative mortality risk that increases with increasing PPM severity, study findings indicate.

Therefore, "[t]he PPM preventive strategy should be individualized according to the anticipated severity of PPM and the patient's baseline risk profile", Victor Dayan (Universidad de la Republica, Montevideo, Uruguay) and colleagues remark.

Dayan and team conducted a meta-analysis of data from 58 studies, published between 1965 and 2014, comparing the outcomes of 40,381 patients with and without PPM. Of these, 39,568 underwent surgical AVR and 813 underwent transcatheter AVR.

The researchers report in JACC: Cardiovascular Imaging that PPM of any degree was associated with a 1.54-fold increased likelihood of perioperative mortality (within 30 days of the procedure) and a 1.26-fold increased likelihood of death overall (peri- and postoperative) compared with no PPM.

The risk of perioperative mortality was greatest in patients with severe PPM (indexed effective orifice area [iEOA] <0.65 cm²/m²), at an odds ratio (OR) of 2.57. These patients were also 1.43 times more likely to die overall than those without PPM.

By contrast, patients with moderate PPM (iEOA ≥0.65 cm²/m² and <0.85 cm²/m²) were more likely to die perioperatively than those with no PPM (OR=1.57) but had no increased risk of overall mortality.

"This may be explained by the fact that once [left ventricular] function and hemodynamics have stabilized following the early post-AVR period, the impact of a moderate PPM on subsequent outcome is less important," the researchers remark.

Predictors of PPM were older age, female gender, hypertension, diabetes, renal failure, larger body surface area, larger body mass index and the use of a bioprosthesis rather than a mechanical valve.

Subgroup analysis revealed that the impact of PPM on mortality was more pronounced in those studies in which the mean age of the patients was below 70 years and/or when AVR with associated coronary artery bypass graft was included. And it was less pronounced in studies in which the mean body mass index (BMI) was below 28 kg/m².

Dayan and team note that among the patients who underwent transcatheter AVR, there was no difference in mortality between those with and without PPM.

"This option should be considered especially in patients <70 years of age and/or with concomitant CABG [coronary artery bypass graft] with high risk of post-operative PPM", they write.

The team concludes: "In light of the results of the present meta-analysis, severe PPM should be avoided in every patient undergoing AVR, whereas preventive measure should be considered in patients with anticipated moderate PPM presenting vulnerability factors to PPM including: age <70 years, BMI <28 kg/m², and concomitant CABG."

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