Abstract
Changes in cardiac mechanics after correction of severe Aortic Stenosis (AS) are under-investigated. Myocardial Work (MW) is emerging as a useful non-invasive correlate of invasively measured myocardial performance and oxygen consumption. The aim of this study was to assess the usefulness of MW in the clinical management of patients with AS undergoing transcatheter aortic valve implantation (TAVI). Consecutive patients referred for TAVI were included in this observational study. Echocardiograms were performed before and after TAVI to measure Global Work Index (GWI), Global Constructive Work (GCW), Global Wasted Work (GWW), and Global Work Efficiency (GWE). Mean transvalvular gradient was significantly improved (p < 0.05), without significant changes in left ventricular ejection fraction, nor in global longitudinal strain (GLS). GWI (p < 0.001) and GCW (p < 0.001), but not GWW (p = 0.241) nor GWE (p = 0.854) were significantly reduced after TAVI. Patients with a low flow low gradient (LF-LG) AS had lower left ventricular ejection fraction (LVEF) (p < 0.001), worse global longitudinal strain (GLS) (p < 0.001), and lower baseline GWI (p < 0.001), GCW (p < 0.001) and GWE (p = 0.003). The improvement in GWI and GCW observed after TAVI in the general study population were abolished among LF-LG patients. In conclusion, non-invasive MW might be useful to further classify patients with AS and to predict non responders.
Highlights
Severe aortic stenosis (AS) is associated with variable degrees of compensatory left ventricular (LV) adaptation [1]
The main results of our study are that (i) correction of severe AS by means of transcatheter aortic valve implantation (TAVI) has a significant impact on non-invasive myocardial work parameters, which are maintained over time during the follow-up; (ii) non-invasive myocardial work indices are capable to further stratify patients with severe AS, as they were able to discriminate between low flow low gradient (LF-LG) AO and the more common form of AS with HG; (iii) the improvement of myocardial work indices after TAVI is not present across patient subgroups, as women tended to experience a less pronounced delta change in myocardial work after TAVI
Since Global Work Index (GWI) and the other myocardial work parameters were validated using non-invasive, peripheral blood pressure, the presence of hemodynamically relevant aortic stenosis poses a critical issue to the application of this analysis in AS patients
Summary
Severe aortic stenosis (AS) is associated with variable degrees of compensatory left ventricular (LV) adaptation [1]. These changes maintain the stroke volume despite the presence of a mechanical obstacle, but they subtly lead to LV dysfunction, and to a rapid clinical progression and a steep worsening of prognosis [2]. Assessment of systolic LV performance in these patients represents a clinical conundrum. Left ventricular ejection fraction (LVEF) generally remains preserved despite initial deterioration of LV function. Global longitudinal strain (GLS) has been shown to be an earlier and more sensitive marker of LV dysfunction [3,4]. Its dependence from afterload represents a limitation in severe AS [5]
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