Left atrial strain predicts exercise capacity in heart failure independently of left ventricular ejection fraction

Abstract

Aims: We hypothesized that left atrial (LA) remodelling and function are associated with poor exercise capacity as prognostic marker in chronic heart failure (CHF) across a broad range of left ventricular ejection fraction (LVEF).

Methods and results: One hundred seventy-one patients with CHF were analysed [age 65 ± 11 years, 136 males (80%); 86 heart failure with reduced ejection fraction (HFrEF), 27 heart failure with mid-range ejection fraction (HFmrEF), 58 heart failure with preserved ejection fraction (HFpEF)]. All patients underwent echocardiography and maximal cardiopulmonary exercise testing and were classified according to a prognostic cut-off of peak VO₂ (pVO₂ ; 14 mL/kg/min). Seventy-seven (45%) patients reached pVO₂ < 14 and 94 (55%) pVO₂ ≥ 14 mL/kg/min. Between the two groups, there was a considerable difference in both left atrial volume (LAVi, 53 ± 24 vs. 44 ± 18 mL/m² , P = 0.005) and function (LA reservoir strain 12 ± 5 vs. 20 ± 10%, P < 0.0001). Receiver-operating characteristic curves identified LA reservoir strain (area under the curve: 0.73 [0.65-0.80], P < 0.0001) as strong predictor for impaired pVO₂ among all echocardiographic variables; LA reservoir strain < 23% had 37% specificity but a very high sensitivity (96%) in identifying a severely reduced pVO₂ . In logistic regression analysis, LA reservoir strain < 23% was associated with a highly increased risk of pVO₂ < 14 mL/kg/min (odds ratio 16.0 [4.7-54.6]; P < 0.0001). The multivariate analysis showed that a reduced LA reservoir strain was associated with pVO₂ < 14 mL/kg/min after adjustment for age, body mass index (BMI), and clinical variables, that is, New York Heart Association class, atrial fibrillation, haemoglobin, and creatinine (b 0.22 [95% confidence interval, CI, 0.12-0.31]; P < 0.0001), and after adjustment for echocardiographic variables, that is, LVEF or left ventricular global longitudinal strain (LVGLS) and tricuspid annular plane systolic excursion (TAPSE) (b 0.16 [95% CI 0.08-0.24]; P < 0.0001). Patients with HFrEF, HFmrEF, and HFpEF were separately analysed. Among LA reservoir strain, LAVi, LVEF, LVGLS, and TAPSE, LA reservoir strain was the only one significantly associated with pVO₂ in all subgroups (after adjustment for sex and BMI, P = 0.003, 0.04, and 0.01, respectively).

Conclusions: In patients with CHF, an impaired LA reservoir function is independently associated with a severely reduced pVO₂ . LA dysfunction represents a marker of poor prognosis across LVEF borders in the CHF population.

Keywords: Cardiopulmonary exercise test; Ejection fraction; Exercise capacity; Heart failure; Left atrial strain; Prognosis.