Preprocedural global myocardial work index independently predicts NT-proBNP in patients undergoing transcatheter aortic valve replacement: a prospective study

Abstract

Abstract Global myocardial work index is a novel echocardiographic parameter of the left ventricular (LV) function, which may overcome the load-sensitvity of the traditional functional measures by measuring LV deformation in the context of simultaneous pressures. This approach may gain particular importance in pressure overload states, such as patients with severe aortic stenosis. However, the longitudinal changes of this recently introduced measure are scarcely investigated in this population, and data are also lacking about its association with functional improvement following transcatheter aortic valve replacement (TAVR). Accordingly, our aim was to investigate the clinical determinants of preoperative and also postoperative GMWI in patients undergoing TAVR. Eighty-four patients (54%% male, age: 79±6 years) were enrolled. Prior to the procedure, subjects underwent echocardiographic investigation and the detailed medical history was also recorded. Serum NT-proBNP levels were also measured. We calculated LV ejection fraction and LV end-diastolic volume (EDV), and speckle-tracking analysis was performed to measure global longitudinal strain (GLS). As an accepted method of its estimation, LV pressure curve was generated by adding the mean aortic valve gradient to the systolic blood pressure. Using these measures, global myocardial work index (GMWI) was quantified by commercially available software. 12 months after the procedure, the patients underwent a follow-up echocardiographic examination, and at that time point we determined the same measures. At follow-up, GLS has significantly increased (-13.5±4.5 vs. -15.2±3.6%; p<0.001), while GMWI was significantly lower at the follow-up assessment (1913±786 vs. 1666±594 mmHg%, p<0.01). Compared to the preoperative values, LVEDV also showed a significant decrease at follow-up (115±46 vs. 105±41 mL, p<0.01). Using multivariable analysis, atrial fibrillation (β=0.36; p<0.001) ischemic heart disease (β=0.20; p<0.05) and also GMWI (β=-0.22; p<0.05) were found to be independent predictors of the postoperative NT-proBNP (R2=0.36; overall p<0.001). Importantly, by replacing GMWI to GLS, the latter did not enter the model as a predictor (β=0.17, p=0.11). TAVR significantly alters LV functional and morphological measures. Regarding the functional outcome of the patients, different clinical factors influence NT-proBNP after the procedure. Possibly due to its significant load dependency, preoperative GLS failed to predict NT-proBNP at follow-up, while GMWI was an independent precictor of NT-proBNP at follow up along with atrial fibrillation and ischemic heart disease. GMWI may serve as a useful imaging marker of preprocedural patient assessment before TAVR.