Prognostic Implications of Preoperative E/e′ Ratio in Patients with Off-pump Coronary Artery Surgery

Abstract

The ratio of early transmitral flow velocity to early diastolic velocity of the mitral annulus (E/e') correlates with left ventricular (LV) filling pressure. In particular, an E/e' ratio more than 15 is an excellent predictor of increased LV filling pressure. The authors evaluated the prognostic implications of preoperative estimated LV filling pressure, assessed by E/e' ratio, in patients undergoing off-pump coronary artery bypass graft surgery. This observational study investigated 1,048 consecutive adults undergoing elective off-pump coronary artery bypass graft surgery. The primary outcome was occurrence of major adverse cardiac events (MACE), defined as a composite of death, myocardial infarction, malignant ventricular arrhythmia, cardiac dysfunction, or need for new revascularization. Logistic regression and survival analyses were performed. An E/e' ratio more than 15 was independently associated with 30-day MACE (odds ratio 2.4, 95% CI 1.4-3.9, P = 0.001) and 1-yr MACE (hazard ratio 2.1, 95% CI 1.4-3.1, P = 0.001), irrespective of underlying LV ejection fraction. MACE free 1-yr survival rate was significantly decreased in patients with E/e' >15, irrespective of underlying LV ejection fraction. Increased LV filling pressure, assessed by E/e' ratio, is an independent predictor of 30-day and 1-yr MACE in patients who undergo elective off-pump coronary artery bypass graft surgery. These findings indicate that measurements of E/e' may assist in preoperative risk stratification of these patients.