Body weight status and post-operative predictive significance of effective prosthetic orifice area after aortic valve replacement

Abstract

The definition of prosthesis-patient mismatch (PPM) remains to be refined to enhance its prognosis insight after SAVR, especially in obese patients. To test the prognostic impact of effective and predicted prosthetic orifice area (OA) according to body weight status after surgical aortic valve replacement (SAVR) for severe aortic stenosis (AS). Between 2009 and 2016, we prospectively explored all consecutive patients referred to our Heart Valve Clinic for a first SAVR for severe AS. Indexed OA predicted from reference normal value (iPOA) and calculated by transthoracic echocardiography (iEOA) were assessed at discharge. Patients were followed for major events (ME), i.e. cardiovascular death, cardiac hospitalization for acute heart failure and stroke. 762 patients were included with a mean follow-up of 4 ± 2.5 years. Severe PPM was more frequently observed with iEOA than iPOA (20.5% vs. 7%, P < 0.0001), with a significant but weak correlation between these 2 parameters ( P < 0.0001, r 2 = 0.21). After multivariable adjustment, low iEOA was the only related prosthetic parameters independently associated with long-term outcome ( P = 0.03), without any difference between moderate and severe PPM. The unique cut-off of 0.85 cm 2 /m 2 of iEOA showed the best accuracy to predict ME in lean and overweight but not in obese patients. This was observed irrespective of the type of prosthesis (mechanical vs biological). No EOA normalization allowed to link EOA to outcome, i.e. ME after SAVR were not driven by prosthetic orifice area in obese patients, suggesting an “obesity paradox”. iEOA with the unique cut-off of 0.85 cm 2 /m 2 showed the best accuracy to predict ME after SAVR in lean and overweight but not in obese patients. Further studies are needed to explore the lack of prognostic insight of PPM in obese patients.