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Is Left Ventricular End-Diastolic Pressure a Better Predictor of Long-Term Survival Versus Left Ventricular Ejection Fraction in Patients Undergoing Coronary Artery Bypass Surgery?
J. Nagendran1, A. Oreopoulos1, C. Norris1, M. James1, J. Appoo2, A. Koshal*1, D. B. Ross*1. 1University of Alberta, Edmonton, AB, Canada, 2University of Calgary, Calgary, AB, Canada,
BACKGROUND:
There are several pre-operative risk factors that are associated with decreased survival in of patients undergoing coronary artery bypass surgery (CABG), including pre-operative depressed left ventricular ejection fraction (LVEF). Recently, there have been studies revealing that elevated pre-operative left ventricular end-diastolic pressure (LVEDP) is an independent predictor of operative mortality for patients undergoing CABG, and may even be a greater risk than LVEF<35%. There is a lack of literature examining the correlation between elevated LVEDP and long-term survival in CABG patients. The objective of this study is to determine if pre-operative elevated LVEDP will better prognosticate long-term survival versus low LVEF in patients undergoing CABG.
METHODS:
Data were collected prospectively from 1996-2002 for all patients undergoing CABG through a combined database. Patients were divided into four groups based on LVEF and LVEDP:
Group 1 (LVEF≥35%, LVEDP<18mmHg),
Group 2 (LVEF<35%, LVEDP<18mmHg),
Group 3 (LVEF≥35%, LVEDP≥18mmHg),
Group 4 (LVEF<35%, LVEDP≥18mmHg).
Long-term analysis was performed using Kaplan-Meier survival curves, and multi-variate Cox proportional hazards modeling was used to determine independent risk factors of mortality.
RESULTS:
There were a total of 2512 (19.4% female) patients undergoing isolated CABG, the mean age was 64±11 years and the mean length of follow-up was 5.5±2.3 years. The 4 groups had similar pre-operative characteristics of age, body mass index, history of cerebrovascular accident (CVA), chronic obstructive pulmonary disease (COPD), hypertension, smoking, and hyperlipidemia. Patients with a low LVEF had a higher incidence of peripheral vascular disease, congestive heart failure (CHF) and history of myocardial infarction (p<0.01). The groups with the better LVEF (Groups 1 and 3) had a significantly better long-term survival compared to groups with depressed LVEF (Groups 2 and 4, p<0.01, Figure). There was no significant correlation between elevated LVEDP and decreased survival, demonstrated by Group 3 (LVEF≥35%, LVEDP≥18mmHg) having a significantly better survival than Group 2 (LVEF<35%, LVEDP<18mmHg, p<0.01, Figure). Cox proportional hazards modeling for the entire cohort identified significant independent risk factors for death were: LVEF<35%, female gender, history of CVA, COPD, and CHF (p<0.01). Elevated LVEDP≥18mmHg was not an independent risk factor for mortality.
CONCLUSIONS:
Elevated LVEDP≥18mmHg is not an independent risk factor for long-term mortality in patients undergoing isolated CABG, and does not prognosticate survival compared to previously established risk factors. Decreased long-term survival best correlated with low LVEF<35%.
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