Transcatheter aortic valve replacement acutely improves left ventricular mechanical efficiency in severe aortic stenosis: effects of different phenotypes

Abstract

Aim: Aortic stenosis is a frequent valvular disease, with transcatheter aortic valve implantation (TAVI) being performed when surgical replacement is at increased risk. However, TAVI-induced effects on myocardial efficiency are unknown. We aimed to investigate changes in LV mechano-energetic pre-/post-TAVI and their prognostic impact.

Methods: A total of 46 patients (25 males) received transesophageal and simultaneous radial pressure plus transaortic gradient monitoring before/immediately after prosthesis deployment. Efficiency was computed as external work/potential energy, as derived from LV pressure-volume plots; myocardial oxygen consumption (MVO₂) was estimated as PWI_mod, i.e. a noninvasively validated alternative for MVO₂ estimation.

Results: TAVI was successful in all patients, peak transaortic gradient decreasing - 40 ± 20 mmHg (p < 0.001). Efficiency improved post-TAVI (+ 0.6 ± 0.12; p = 0.004), with a concomitant PWI_mod reduction (- 16 ± 31%; p < 0.001). When contextualized to fixed PWI_mod value (5 ml/min/100 g), efficiency significantly affected survival (p = 0.029). Over 1026 ± 450-day follow-up, a change in efficiency pre-/post-TAVI ≤ 0.021 (median of the difference) predicted more deaths from any cause (30%) as compared with a change > 0.021 (17%), particularly in those patients with a pre-TAVI mean high-gradient (HG ≥ 40 mmHg) phenotype (p < 0.05). In particular, HG patients exhibited the lowest efficiency/PWI_mod ratio pre-/post-TAVI (p = 0.048), relative to the other aortic stenosis patients, suggestive of an unfavourable matching between cardiac function and metabolic demand, which foreshortens some intrinsic damaged muscle condition in these patients.

Conclusion: LV mechanical efficiency improves immediately post-TAVI, notwithstanding an inhomogeneous mechano-energetic matching among the aortic stenosis patients, which can impact negatively on their long-term prognosis, particularly in those with the HG phenotype.

Keywords: Aortic stenosis phenotypes; Aortic valve stenosis; Myocardial efficiency; Oxygen consumption; Pressure–volume plot; Transcatheter aortic valve implantation.