Improving Outcomes and Quality of Life After CABG

BACKGROUND:

Surgical myocardial revascularization (CABG) is an effective treatment for triple vessel and left main coronary artery disease used for thousands of patients annually in the United States. CABG certainly prolongs life, and data demonstrates that it improves functional status for the majority of patients. The intervention in this trial is based upon the outcomes of the investigators' first trial, which showed a benefit to maintaining mean intra-bypass mean arterial pressure (MAP) at 65 mm Hg in the high MAP group vs. 52 mm Hg in the low MAP group. Intra-bypass MAPs corrected for intervals less than full flow were 81 mm Hg for the high group and 59 mm Hg for the low MAP group. Cardiac and neurologic morbidity and mortality were 4.8 percent in the high MAP group versus 12.9 percent in the low MAP group (p=.026). All adverse outcomes were lower in the high MAP group (16.1 percent) than in the low MAP group (27.4 percent). Data from the previous study also suggests that outcomes may be further improved by maintaining intra-bypass MAP close to the patient's preoperative MAP. This is consistent with the investigators previous work in non-cardiac surgery, which shows that maintaining MAP within patient's usual autoregulatory range is associated with lower cardiac and renal complication rates. This study will determine whether refining the approach to hemodynamic management will further improve patient outcomes after coronary revascularization.

DESIGN NARRATIVE:

The First Clinical Study

During the first three years of grant support, from August, 1991 to November, 1995, clinical research was conducted on a comparison of intraoperative high versus low mean arterial pressure (MAP) on outcomes after coronary artery bypass. In this study, 248 patients undergoing primary, nonemergency coronary bypass were randomized to either low (n = 124) or high (n = 124) mean arterial pressure during cardiopulmonary bypass. The impact of the mean arterial pressure strategies on the following outcomes was assessed: mortality, cardiac morbidity, neurologic morbidity, cognitive deterioration, and changes in quality of life. All patients were observed prospectively to six months after the operation. Results are described under the Results Section.