Intraoperative global longitudinal strain and strain rate as predictors of unfavorable outcome following on-pump mitral surgery: a prospective observational study

Background: Low cardiac output syndrome (LCOS) is a life-threatening complication following cardiac surgery. We explored the predictive value of transesophageal echocardiography (TEE)-measured global longitudinal strain (GLS) and strain rate (SR) to establish clinically relevant thresholds for both GLS and SR to subsequently develop a predictive model for LCOS. Methods: A trained anesthesiologist performed standard TEE after general anesthesia induction and before establishment of cardiopulmonary bypass. GLS and SR were obtained using 2D speckle tracking. The occurrence of LCOS after mitral surgery was the primary outcome. Predictive accuracy was assessed using receiver operating characteristic (ROC) curves and Youden index. A multivariable logistic regression model was internally validated via bootstrapping. Associations between GLS categories (< − 19.1 vs > − 19.1%) and outcomes were evaluated using inverse probability of treatment weighting (IPTW). Results: In 126 included patients, LCOS occurred in 31 (25%) instances. Optimal cut-offs to predict LCOS were > − 19.1% for GLS (area under the curve [AUC], 0.79; P < 0.001) and ≤ − 0.98 s−1 for SR (AUC, 0.66; P = 0.01). Predictors for LCOS were GLS > − 19.1%, tricuspid annular plane systolic excursion (TAPSE), ejection fraction (EF), and creatinine clearance (CrCl). The model showed strong performance (R2, 0.580; c-statistic, 0.898; optimism-corrected R2 = 0.517 and AUC 0.77). GLS > − 19.1% was also associated with time on mechanical ventilation (P = 0.015), length of ICU (P = 0.004), and hospital stay (P < 0.001). After IPTW-weighted analyses, patients with GLS > − 19.1% had significantly higher odds of developing postoperative LCOS (odds ratio, 5.48; 95% confidence interval, 1.63–18.5; P = 0.006). Conclusions: We found that GLS, TAPSE, EF, and CrCl were independent predictors of postoperative LCOS in patients undergoing mitral surgery. Among them, a GLS value > − 19.1% was associated with higher odds of LCOS. Clinical trial number: ClinicalTrials.gov, NCT04045340, date of registration: 02.08.2019.