[Prospective risk analysis in patients submitted to myocardial revascularization surgery]

Abstract

Objective: To perform a stratified risk analysis in Myocardial Revascularization Surgery (MRS).

Methods: 814 patients were prospectively studied by applying two prognostic indexes (PI): Parsonnet and Modified Higgins. The Higgins PI was modified by substituting the variable "cardiac index value" by "low cardiac output syndrome" at the Intensive Care Unit (ICU) admission. The discriminatory capacity for morbimortality of both indexes was analyzed by ROC (receiver operating characteristic) curve. Logistic reaction identified the associated factors, independently from the events.

Results: Mortality and morbidity rates were 5.9% and 35.5%, respectively. The Modified Higgins PI, which analyzes pre- and intra-operative and physiological variables at the ICU admission showed areas under the ROC curve of 77% for mortality and 67% for morbidity. The Parsonnet PI, which only analyzes pre-operative variables, showed areas of 62.2% and 62.4%, respectively. Twelve variables were characterized as independent prognostic factors: age, diabetes mellitus, low body surface, creatinine levels (>1.5 mg/dL), hypoalbuminemia, non-elective surgery, prolonged time of extracorporeal circulation (ECC), necessity of post-ECC intra-aortic balloon, low cardiac output syndrome at the ICU admission, elevated cardiac frequency, decrease in serum bicarbonate concentrations and increase of the alveolar-arterial oxygen gradient within this period.

Conclusion: The Modified Higgins PI showed to be superior to the Parsonnet PI at the surgical risk stratification, showing the importance of the analysis of intraoperative events and physiological variables at the patient's ICU admission, when prognostic definition is achieved.