Letter by Augoustides Regarding Article, “Risk Index for Perioperative Renal Dysfunction/Failure: Critical Dependence on Pulse Pressure Hypertension”
To the Editor:
I read with great interest the excellent article by Dr Aronson and colleagues detailing a risk index for perioperative renal dysfunction/failure after coronary revascularization requiring cardiopulmonary bypass.1 Their multivariate analysis has demonstrated the critical role of pulse pressure hypertension in perioperative renal injury. However, the data analysis, as presented, does not account for aprotinin exposure, a significant risk factor for perioperative renal injury as previously described by this research group.2
The consequent questions that arise from this observation include:
What percentage of the study cohort (n=4801) was exposed to aprotinin?
Was aprotinin exposure statistically equivalent in the derivation (n=2381) and validation (n=2420) cohorts?
Is aprotinin exposure an independent predictor for renal injury in this study? If not, what are the possible explanations, given the prior published findings2?
Is the described nephrotoxic interaction between angiotensin blockade and aprotinin an independent predictor of renal injury in this study?3 This consideration is relevant given that 43.9% of the total study cohort were taking preoperative ACE inhibitors.
Is aprotinin exposure an independent predictor of renal injury with or without exposure to angiotensin blockade?3 In the report by Kincaid and colleagues,3 it was the combination of aprotinin and angiotensin blockade that was independently associated with renal failure after cardiac surgery with cardiopulmonary bypass.
I congratulate the authors on a most thought-provoking report. I look forward to understanding better the role of aprotinin exposure in their detailed study of renal injury after coronary revascularization requiring cardiopulmonary bypass.
Financial support for the author was provided by the Department of Anesthesiology and Critical Care, Hospital of the University of Pennsylvania. The author reports no conflicts.
Aronson S, Fontes ML, Miao Y, Mangano DT; for the Investigators of the Multicenter Study of Perioperative Ischemia and the Ischemia Research and Education Foundation. Risk index for perioperative renal dysfunction/failure: critical dependence on pulse pressure hypertension. Circulation. 2007; 115: 733–742.