Aims: Global longitudinal strain (GLS) seems accurate for detecting subclinical myocardial dysfunction, and may therefore be used to improve risk stratification for cardiac surgery.
Methods and results: Longitudinal strain (by two-dimensional speckle tracking) was computed in 425 patients [mean age 67 ± 13 years, 69% male, left ventricular ejection fraction (LVEF) 51 ± 13%] referred for cardiac surgery [isolated coronary artery bypass graft (CABG) (n = 155), aortic valve surgery (n = 174), mitral surgery (n = 96)]. GLS (global-ε) was assessed for predicting early postoperative death. Despite a fair correlation between LVEF and global strain (r = -0.73, P < 0.0001), 40% of patients with preserved LVEF (defined as LVEF ≥50%) had abnormal global-ε (defined as global-ε >-16%): -12.8 ± 1.7%, range -15% to -8%. In patients with preserved LVEF, NT-proBNP level (983 vs. 541 pg/mL, P = 0.03), heart failure symptoms (NYHA class, 2.2 ± 0.9 vs. 1.9 ± 0.9, P = 0.02), and the need for prolonged (>48 h) inotropic support after surgery (33.3 vs. 21.2%, P = 0.03) were greater when global-ε was impaired. Importantly, despite similar EuroSCORE (9.7 ± 12 vs. 7.7 ± 9%, P = 0.2 for EuroSCORE I and 4.2 ± 6.2 vs. 3.4 ± 4.9%, P = 0.4 for EuroSCORE II), the rate of postoperative death was 2.4-fold (11.8 vs. 4.9%, P = 0.04) in patients with preserved LVEF when global-ε was impaired. Multivariate analysis showed that global-ε is an independent predictor for early postoperative mortality [odds ratio = 1.10 (1.01-1.21)] after adjustment to EuroSCORE.
Conclusion: GLS has an incremental value over LVEF for risk stratification in patients referred for cardiac surgery.