A prospective evaluation of hemodynamic instability during off-pump coronary artery bypass surgery

Abstract

Objective: Despite recognized hemodynamic derangements during cardiac displacement, most patients appear to tolerate the off-pump procedure well. However, some patients unpredictably become hemodynamically unstable requiring emergency cardiopulmonary bypass or intra-aortic balloon pump support. After an experience of 5,306 multivessel off-pump coronary artery bypasses (OPCABs), this study was undertaken to determine the factors that would identify the patients who were at a higher risk for the procedure. Design: Prospective clinical investigation. Setting: Tertiary care academic cardiac care center. Participants: Five hundred consecutive patients undergoing multivessel OPCAB from September to December 2001. Interventions: Various cardiac and extracardiac factors were charted in prespecified data-entry forms. Multiple logistic regression analysis was done to determine if any identifiable factors were predictors of a higher risk of unacceptable hemodynamic instability during OPCAB. Institution of IABP support or conversion to CPB were the endpoints of the study. Measurements and Main Results: Of the 500 patients studied, significant hemodynamic instability developed in 24 (4.8%) patients. IABP support was instituted in 16 (3.2%) patients, and 8 (1.6%) were converted to CPB. Stepwise logistic regression identified ejection fraction <25% ( p < 0.001), myocardial infarction of <1-month duration ( p = 0.009), congestive heart failure ( p = 0.016), and preoperative hemodynamic instability ( p = 0.057) as predictors of conversion during OPCAB. Conclusions: Patients with low left ventricular ejection fraction <25%, myocardial infarction of <1-month duration, congestive heart failure, or preoperative hemodynamic instability constitute the high-risk group for OPCAB.