Sensitivity of ventricular systolic function to afterload during veno-arterial extracorporeal membrane oxygenation.

Abstract

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) increases afterload to the injured heart and may hinder myocardial recovery. We aimed to compare the sensitivity of left ventricular (LV) systolic function to the afterload effects of peripheral V-A ECMO during the acute and delayed stages of acute myocardial dysfunction. A total of 46 adult patients who were supported by peripheral V-A ECMO between April 2019 and June 2021 were analysed. Serial cardiac performance parameters were measured by transthoracic echocardiography (TTE) on mean day 1±1 of V-A ECMO initiation (n=45, 'acute phase') and mean day 4±2 of V-A ECMO initiation (n=36, 'delayed phase'). Measurements were obtained at 100%, 120%, and 50% of ECMO target blood flow (TBF). LV global longitudinal strain (GLS) significantly improved from -6.1 (-8.9 to -4.0)% during 120% TBF to -8.8 (-11.5 to -6.0)% during 50% TBF (P<0.001). The sensitivity of LV GLS to changes in ECMO flow was significantly greater in the acute phase of myocardial injury compared with the delayed phase [median (IQR) percentage change: 72.7 (26.8-100.0)% vs. 22.5 (14.9-43.8)%, P<0.001]. Findings from other echocardiographic parameters including LV ejection fraction [43.0 (29.1-56.8)% vs. 22.8 (9.2-42.2)%, P=0.012] and LV outflow tract velocity-time integral [45.8 (18.6-58.7)% vs. 24.2 (12.6-34.0)%, P=0.001] were similar. A total of 24 (52.2%) patients were weaned off ECMO successfully. We demonstrated that LV systolic function was significantly more sensitive to the afterload effects of V-A ECMO during the acute stage of myocardial dysfunction compared with the delayed phase. Understanding the evolution of the heart-ECMO interaction over the course of acute myocardial dysfunction informs the clinical utility of echocardiographic assessment in patients on V-A ECMO.