Reduced left ventricular contractility, increased diastolic operant stiffness and high energetic expenditure in patients with severe aortic regurgitation without indication for surgery

Abstract

Objectives: Recent mortality studies showed worse prognosis in patients (ARNS) with severe aortic regurgitation and preserved ejection fraction (EF) not fulfilling the criteria of current guidelines for surgery. The aim of our study was to analyse left ventricular (LV) systolic and diastolic function and mechanical energetics to find haemodynamic explanations for the reduced prognosis of these patients and to seek a new concept for surgery.

Methods: Global longitudinal strain (GLS) and echo-based single-beat pressure-volume analyses were performed in patients with ARNS (LV end-diastolic diameter <70 mm, EF >50%, GLS > -19% n = 41), with indication for surgery (ARS; n = 19) and in mild hypertensive controls (C; n = 20). Additionally, end-systolic elastance (LV contractility), stroke work and total energy (pressure-volume area) were calculated.

Results: ARNS demonstrated significantly depressed LV contractility versus C: end-systolic elastance (1.58 ± 0.7 vs 2.54 ± 0.8 mmHg/ml; P < 0.001), despite identical EF (EF: 59 ± 6% vs 59 ± 7%). Accordingly, GLS was decreased [-15.7 ± 2.7% (n = 31) vs -21.2 ± 2.4%; P < 0.001], end-diastolic volume (236 ± 90 vs 136 ± 30 ml; P < 0.001) and diastolic operant stiffness were markedly enlarged, as were pressure-volume area and stroke work, indicating waste of energy. The correlation of GLS versus end-systolic elastance was good (r = -0.66; P < 0.001). ARNS and ARS patients demonstrated similar haemodynamic disorders, whereas only GLS was worse in ARS.

Conclusions: ARNS patients almost matched the ARS patients in their haemodynamic and energetic deterioration, thereby explaining poor prognosis reported in literature. GLS has been shown to be a reliable surrogate for LV contractility, possibly overestimating contractility due to exhausted preload reserve in aortic regurgitation patients. GLS may outperform conventional echo parameters to predict more precisely the timing of surgery.

Keywords: Aortic regurgitation; Contractility; End-systolic elastance; Global longitudinal strain; Stroke work.