Background: The ratio of early transmitral flow velocity to early diastolic velocity of the mitral annulus (E/e') is an indicator of diastolic function that correlates well with left ventricular (LV) filling pressure and is relatively independent of systolic function and rhythm abnormalities. We prospectively evaluated the predictive value of E/e' for postoperative outcome in patients undergoing off-pump coronary artery bypass graft surgery (OPCAB).
Methods: Patients undergoing OPCAB were classified into three groups according to their E/e' ratio: (i) normal E/e' <8; (ii) undetermined E/e' ≥8 and ≤15; and (iii) elevated E/e' >15. Among those with E/e' between 8 and 15, patients with elevated LV filling pressure were further identified by comprehensive Doppler examination. These patients were classified as having a high LV filling pressure, together with patients who had E/e' ratios >15. Univariate and multivariate regression analyses were used to evaluate the relationship between preoperative variables and composite endpoints for morbidity.
Results: In univariate analysis, diabetes mellitus, recent myocardial infarction, chronic obstructive pulmonary disease, serum creatinine (sCr) concentration, E/e' >15, high LV filling pressure, LV ejection fraction, New York Heart Association class III and IV, and use of diuretics were significant risk factors for postoperative morbidity. In multivariate regression analysis of these variables, only sCr (odds ratio 1.4) and E/e' >15 (odds ratio 2.4) or high LV filling pressure (odds ratio 2.8) remained as independent risk factors.
Conclusions: E/e' ratio >15 was a significant predictor of composite endpoints of postoperative morbidity. We suggest that E/e' ratio should be included in the routine preoperative assessment of patients presenting for OPCAB.