PREDICTORS OF LOW CARDIAC-OUTPUT SYNDROME AFTER CORONARY-ARTERY BYPASS

The purpose of this study was to identify patients at risk for the dev elopment of low cardiac output syndrome after coronary artery bypass. Low cardiac output syndrome was defined as the need for postoperative intraaortic balloon pump or inotropic support for longer than 30 minut es in the intensive care unit to maintain the systolic blood pressure greater than 90 mm Hg and the cardiac index greater than 2.2 L/min per square meter, The preoperative patient characteristics that were inde pendent predictors of loa cardiac output syndrome were identified amon g 4558 consecutive patients who underwent isolated coronary artery byp ass at The Toronto Hospital between July 1, 1990, and December 31, 199 3, The overall prevalence of low cardiac output syndrome was 9.1% (n = 412). The operative mortality rate n as higher in patients in a hom l ow cardiac output syndrome developed than in those in whom it did not develop (16.9% versus 0.9%, p < 0.001), Stepwise logistic regression a nalyses identified nine independent predictors of low output syndrome (percent frequency in parentheses) and calculated the factor-adjusted odds ratios associated with each predictor: (1) left ventricular eject ion fraction less than 20% (27%, odds ratio 5.7); (2) repeat operation (25%, odds ratio 4.4); (3) emergency operation (27%, odds ratio 3.7); (4) female gender (16%, odds ratio 2.5); (5) diabetes (13%, odds rati o 1.6); (6) age older than 70 years (13%, odds ratio 1.5); (7) left ma in coronary artery stenosis (12%, odds ratio 1.4); (8) recent myocardi al infarction (16%, odds ratio 1.4); and (9) triple-vessel disease (10 %, odds ratio 1.3), Lon cardiac output syndrome is a clinical outcome that may result from inadequate myocardial protection or perioperative ischemic injury, patients at high risk for the development of low car diac output syndrome should he the focus of trials of new techniques o f myocardial protection to resuscitate the ischemic myocardium.