Pressure-volume-strain-derived myocardial work: a novel prognostic marker in patients undergoing transcatheter aortic valve replacement

Abstract Aortic stenosis (AS) is the most prevalent valvular heart disease in developed countries, most frequently affecting elderly, multimorbid patients. Transcatheter aortic valve replacement (TAVR) revolutionized the treatment of this population. Left ventricular (LV) functional assessment is a key element in the diagnostic workup of AS, however, conventional echocardiographic parameters such as ejection fraction (EF) and global longitudinal strain (GLS) are heavily dependent on LV loading conditions. Myocardial work analysis may be a more appropriate method of functional assessment in this LV pressure overload setting, however, pressure-strain analysis still neglects LV geometry and preload. Accordingly, the aim of our study was to incorporate LV volume into myocardial work analysis and to test the prognostic value of pressure-volume-strain loop-derived myocardial work in patients undergoing TAVR. 316 patients (age: 79±6 years, 41% female) undergoing TAVR were enrolled. We performed detailed echocardiographic examinations and took non-invasive blood pressure measurements the day before the procedure. EF and LV volumes throughout the entire cardiac cycle were measured using the biplane Simpson method while speckle-tracking analysis was used to determine GLS values. A reference LV pressure curve was created using left heart catheterization data and individual pressure curves were generated using the noninvasive blood pressure and the Doppler-derived mean transaortic gradient. Global constructive work (GCW) was calculated by utilizing strain rate and LV pressure curves. We further adjusted the pressure-strain to instantaneous LV volumes and therefore, we constructed pressure-strain-volume loops and quantified volume-adjusted GCW (GCWV). Our primary outcome was all-cause death, reached by 68 patients during a median follow-up of 25 months. Low-flow low-gradient patients had comparable GCW to normal flow patients (1218±595 vs. 1353±507 Hgmm%, p=0.11), however, GCWV was significantly lower in the low-flow low-gradient group (121.9±40.8 vs 112.0±51.8 Hgmm%L, p=0.03). Using univariate Cox regression analysis, EF was not a significant predictor, however, GLS (HR: 1.083 1.017-1.154, p=0.01), GCW per 100 unit change (HR: 0.951 (0.907-0.997, p=0.04) and also GCWV per 10 unit change (HR: 0.935 0.881-0.993, p=0.03) were significantly associated with outcome. In a multivariable Cox regression model, GCWV emerged as a significant independent predictor (HR: 0.928 0.870-0.991, p=0.03) along with age, sex, atrial fibrillation, diabetes mellitus and hemoglobin, while other LV functional parameters did not. GCWV was an independent predictor of outcome in our cohort, while conventional measures and even conventional myocardial work was not. Integrating volume into the myocardial work analysis and pressure-volume-strain loop-derived measures may be sensitive markers of load-independent LV function providing added prognostic value in TAVR patients.