Which risk score best predicts perioperative outcomes in nonvalvular atrial fibrillation patients undergoing noncardiac surgery?

BACKGROUND: Patients with nonvalvular atrial fibrillation (NVAF) are at increased risk for adverse events after noncardiac surgery. The Revised Cardiac Index (RCI) is commonly used to predict perioperative events; however, the prognostic utility of NVAF risk scores (CHADS2, CHA2DS2-VASc, and R2CHADS2) has not been evaluated in patients undergoing noncardiac surgery.

METHODS: Using a population-based data set of NVAF patients (n = 32,160) who underwent major or minor noncardiac surgery between April 1, 1999, and November 30, 2009, in Alberta, Canada, we examined the incremental prognostic value of the CHADS2, CHA2DS2-VASc, and R2CHADS2 scores over the RCI using continuous net reclassification improvement (NRI). The primary composite outcome was 30-day mortality, stroke, transient ischemic attack, or systemic embolism.

RESULTS: The median age was 73 years, 55.1% were male, 6.6% had a previous thromboembolism, 17% of patients underwent major surgery, and the median risk scores were as follows: RCI = 1, CHADS2 = 1, CHA2DS2-VASc = 3, and R2CHADS2 = 2. The incidence of our 30-day composite was 4.2% (mortality 3.3%; stroke, transient ischemic attack, or systemic embolism 1.2%); and c indices were 0.65 for the RCI, 0.67 for the CHADS2 (NRI 14.3%, P < .001), 0.67 for CHA2DS2-VASc (NRI 10.7%, P < .001), and 0.68 for R2CHADS2 (NRI 11.4%, P < .001). The CHADS2, CHA2DS2-VASc, and R2CHADS2 scores were also all significantly better than the RCI for mortality risk prediction (NRI 12.3%, 8.4%, and 13.3%, respectively; all Ps < .01).

CONCLUSIONS: In NVAF patients undergoing noncardiac surgery, the CHADS2, CHA2DS2-VASc, and R2CHADS2 scores all improved the prediction of major perioperative events including mortality compared to the RCI.