PERIOPERATIVE RENAL DYSFUNCTION IN CARDIAC SURGICAL PATIENTS beta ADRENERGIC RECEPTOR BLOCKADE DOES NOT INFLUENCE

Abstract

Introduction: Renal dysfunction following cardiac surgery is common and associated with major increases in morbidity, mortality, and cost. [1] beta adrenergic receptor (AR) blockade prior to renal insult has been shown to be beneficial in a model of ischemic renal injury. [2,3,4] We therefore tested the hypothesis that beta AR blockade is associated with reduced post cardiac surgery renal dysfunction. Methods: With IRB approval, 99 patients undergoing primary CABG were randomized to receive placebo (group 1) or metoprolol 10 mg, 20 mg, or 30 mg (groups 2, 3 and 4 respectively) as part of an ongoing myocardial protection study. Creatinine clearance (CrCl) values were estimated using the Cockcroft and Gault equation. [5] Associations were assessed by ANOVA, p<0.05 was considered significant. Results: Demographic variables were similar among groups except for age (see Table 1). No significant difference was demonstrated in the change in rank CrCl among all four groups or between groups 1 and 4, after controlling for baseline CrCl, and age (see Table 1). The data provided 80% power to detect a difference of 12 ml/min in delta CrCl between patients who received metoprolol (Group 2,3, and 4) and patients who received no metoprolol (Group 1). Categorical variables were tested with Chi square test of general association. Continuous variables were tested with standard t-test.Table 1: Demographics and CrCl values for study groupsDiscussion: The findings of this study do not support previous animal data suggesting that beta AR blockade has renal protective potential. The observation that beta AR blockade is not protective in a cardiopulmonary bypass model does not exclude the possibility that this therapy may be protective in other settings.