Left Atrial Strain as a Single Parameter to Predict Left Ventricular Diastolic Dysfunction and Elevated Left Ventricular Filling Pressure in Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

Abstract

Objective: Left ventricular diastolic dysfunction (LVDD) is very common among patients undergoing cardiac surgery and is associated with increased mortality and morbidity. The present study tested the hypothesis of whether left atrial strain (LAS) can be used as a single parameter to predict LVDD (per 2016 LVDD evaluation guidelines) and elevated left ventricular filling pressure (LVFP) (ie, LVDD grades II and III) in patients scheduled for off-pump coronary artery bypass grafting (OPCABG) surgery.

Design: A prospective observational study.

Settings: Tertiary-care level hospital.

Participants: The study comprised 60 patients undergoing elective OPCABG.

Interventions: None.

Measurements and main results: Transthoracic echocardiography was performed within 24 hours of surgery by an anesthesiologist. LVDD was graded per American Society of Echocardiography/European Association of Cardiovascular Imaging recommendations for 2016 LVDD guidelines. Left atrial (LA) function was evaluated using two-dimensional strain measurements obtained with the speckle-tracking echocardiography technique. Receiver operating characteristic curves were constructed, and the area under the curve was derived for the prediction of elevated LVFP by LAS. Fourteen (23.3%) patients had elevated LVFP. Global LA reservoir strain (LAS_r) reduced significantly as the LVDD grade worsened (28.9% ± 8.3%, 21.8% ± 7.2%, 15.6% ± 4.5% and 11.9% ± 1.3%, respectively, for normal LV diastolic function and grades I, II, and III LVDD; p < 0.0001). Similar trends were noted for other components of LAS; namely, global LA conduction, global LA contraction strain, and LAS rate. The ability to predict high LVFP with LAS_r was statistically significant, with an area under the receiver operating characteristic curve of 0.92 (confidence interval 0.82-0.97; p < 0.001), and a Youden's index for LAS_r of 19% was obtained with 85.71% sensitivity and 84.78% specificity. The ability of LAS and its components to predict increased LVFP in various subpopulations (normal v reduced ejection fraction) yielded statistically significant results.

Conclusions: In patients scheduled for OPCABG, cardiac anesthesiologists successfully could measure LAS with speckle-tracking echocardiography in the preoperative period. LAS as a single parameter was significantly associated with the grade of LVDD. LAS_r decreased significantly with worsening grade of LVDD. Furthermore, an LAS_r value <19% significantly predicted a high LVFP, and LAS_r predicted high LVFP in both preserved and reduced ejection fraction equally well.

Keywords: LVDD; left atrial pressure; left atrial strain; left ventricular diastolic dysfunction; left ventricular filling pressure.