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 our data demonstrates that it improves functional status for the majority of patients. The proposed intervention in this trial is based upon the outcomes of our previous 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 was 4.8% in the high MAP group vs. 12.9% in the low MAP group (p=.026). All adverse outcomes were lower in the high MAP group (16.1%) than in the low MAP group (27.4%). 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 our 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. Among patients undergoing elective primary CABG, the principal objective of this randomized trial is to compare the efficacy of two strategies of intra-operative hemodynamic management during cardiopulmonary bypass in preventing peri-operative cardiac, cognitive and neurologic morbidity and mortality, and post-operative deterioration in patients' quality of life as measured by the SF-36. The study is a prospective trial of 412 patients who will be evaluated pre-operatively, monitored intra-operatively and followed post-operatively according to a standardized surveillance protocol. Patients will be randomized to two forms of hemodynamic management during cardiopulmonary bypass. In one group, the intra-operative MAP during bypass will be maintained at 65 mm Hg (or 81 mm Hg at full flow), thus employing the most effective strategy from our previous trial. In the second group, the intra-operative MAP will be maintained at their pre-operative MAP (but below 90 mm Hg), a strategy supported by data from the previous trial. The principal outcome is the occurrence of any one of the following: mortality at six months, major cardiopulmonary morbidity (i.e., myocardial infarction, pulmonary edema, cardiogenic shock or low flow state), cognitive complications (defined by a summary definition which includes improvement and decline on neuropsychologic tests of memory, psychomotor/attention, and linguistic function), major neurologic complications (i.e., new focal deficits, such as hemiplegia, aphasia, cortical blindness) and significant deterioration in functional status at six months postoperatively. The long term objective is to preserve and further improve the quality of life after CABG. This study will determine whether refining the approach to hemodynamic management will further improve patient outcomes after coronary revascularization.
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