Global Longitudinal Strain as a Predictor of Difficult Separating From Cardiopulmonary Bypass

Background and Rationale

Difficult separation from cardiopulmonary bypass (CPB) is a serious intraoperative complication associated with increased perioperative morbidity and mortality. Myocardial contractility is the key determinant of successful CPB separation, and perioperative echocardiography is an established method for evaluating ventricular function. Conventionally, left ventricular ejection fraction (LVEF) measured by Simpson's biplane method is used to assess myocardial performance. However, LVEF has notable limitations, including high inter-operator variability, preload/afterload dependence, and poor sensitivity in detecting early myocardial dysfunction.

Global longitudinal strain (GLS), measured by two-dimensional speckle-tracking echocardiography, has emerged as a sensitive, reproducible, and geometry-independent parameter of myocardial function. GLS can detect subtle ventricular dysfunction earlier than conventional LVEF and has demonstrated prognostic value in a variety of clinical settings. Despite this, its use in the perioperative cardiac surgery population remains limited, partly due to uncertainty about the optimal timing of assessment. Anesthesia induction, CPB, and myocardial protection strategies may alter myocardial performance, and therefore both absolute GLS values and dynamic perioperative changes may carry prognostic significance.

Study Objectives

The primary objective of this prospective, multicenter, observational study is to evaluate the predictive value of GLS measurements for difficult separation from CPB. Specifically, the study will assess whether GLS measured by preoperative transthoracic echocardiography (TTE) can independently predict the need for multiple inotropic/vasoactive agents during CPB weaning.