Effects of prosthesis-patient mismatch in patients with low flow, low gradient and with low left ventricular ejection fraction after aortic valve replacement surgery

Background: Aortic valve stenosis, one of the most common valvular diseases in the elderly, has the highest morbidity and mortality rate of any valvular disease. There is a subset of patients with aortic valve stenosis who have low flow, low gradient (LFLG) and low left ventricular ejection fraction (LVEF), defined as an aortic valve area of \u3c 1 cm2, a transvalvular gradient of \u3c 40 mmHg and LVEF of ≤ 40%. Compared to normal-flow aortic valve stenosis, patients with LFLG and low LVEF are known to have a high operative mortality rate. There are a number of factors that influence peri- and postoperative mortality in patients with LFLG and low LVEF, such as a decreased contractile reserve of the left ventricle. There have been studies that show that prosthesis-patient mismatch (PPM) may independently affect postoperative mortality and the recovery of the left ventricle after aortic valve replacement (AVR) in patients with normal-flow aortic valve stenosis. Purpose: The purpose of this study is to investigate PPM on the recovery of the left ventricle in patients with LFLG and low LVEF aortic valve stenosis. Methods: We conducted a retrospective chart review of patients with LFLG and low LVEF who underwent AVR for severe aortic valve stenosis at Aurora St. Luke’s Medical Center from January 2007 to December 2012. Two- dimensional echocardiograms of these patients pre- and post-AVR were reviewed, and effective orifice area index (EOAi) for the different valves implanted was obtained. Based on the calculated EOAi, patients were separated into different categories: namely, hemodynamically insignificant PPM, moderate PPM and severe PPM, defined as EOAi \u3e 0.85 cm2/m2 , \u3e 0.65 to 0.85 cm2/m2, and ≤ 0.65 cm2/m2, respectively. Results: Of the 1,882 patients who underwent AVR, a total of 254 (13%) patients met the criteria for LFLG and low LVEF and 65 patient charts contained data that was complete and allowed comprehensive review. Of these 65 (75% male), mean age was 77 ± 10 years; prevalence of coronary artery disease was 77%, hypertension 72% and hyperlipidemia 54%. Median New York Heart Association class was II. Moderate or severe PPM was present in 28 patients (42%). LVEF pre- and up to 1-year post-AVR in the patients with moderate or severe PPM was 30 ± 6% and 33 ± 13% (P=0.29), respectively, whereas patients with insignificant PPM had pre- and up to 1-year post-AVR LVEF of 29 ± 7% and 39 ± 13% (P=0.002), respectively. Conclusion: In patients with LFLG and low LVEF, the presence of moderate to severe PPM may adversely affect the recovery of the left ventricle after AVR surgery