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

https://doi.org/10.1016/j.ahj.2014.03.015Get rights and content

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.

Section snippets

Study design and data sources

We established a population-based inception cohort of patients with NVAF who underwent noncardiac surgery at varying times after diagnosis of NVAF, and examined outcomes in the first 30 days after surgery. As previously described,22 the data set was created by linking 5 administrative databases in the province of Alberta, Canada, and following each NVAF case using each patient’s unique personal identifier: (1) the Alberta Inpatient Discharge Abstract Database, which records information for all

Results

The final study sample included 32,160 NVAF patients who underwent major or minor noncardiac surgery between April 1, 1999, and November 30, 2009 (Figure 1). The 30-day primary composite outcome of death, stroke, TIA, or SE was 4.2%; 30-day perioperative mortality rate was 3.3%; and the incidence of stroke, TIA, or SE in the first 30 days after surgery was 1.2%. Patients with perioperative events were older and more likely to have a history of hypertension, diabetes, coronary artery disease, a

Discussion

In this large population-based cohort of NVAF patients undergoing noncardiac surgery, we found that the CHADS2, CHA2DS2-VASc, and R2CHADS2 scores were all superior to the RCI for predicting risk of death and/or the risk of stroke, TIA, or SE in the first 30 days after surgery.

Despite an increasing prevalence of NVAF in the general population, the optimal means of preoperative risk stratification in this population has not been previously described.1 This may, in part, be due to the conflicting

Conclusions

In a large unselected population-based cohort of patients undergoing noncardiac surgery, we found that CHADS2, CHA2DS2-VASc, and R2CHADS2 were all modestly superior to RCI for the prediction of 30-day major perioperative events including mortality and/or stroke/TIA/SE. The observed NRI suggests that the 3 thromboembolic risk models evaluated can improve the preoperative risk stratification of patients with NVAF undergoing noncardiac surgery.

Funding

J. E. A. is supported by a salary award from Alberta Innovates—Health Solutions. F. A. M. is supported by Alberta Innovates—Health Solutions and the University of Alberta Chair in Cardiovascular Outcomes.

Conflicts of interest

S. v. D., E. Y., J. A. E., and F. A. M: none.

Acknowledgements

This study is based in part on data provided by Alberta Health. The interpretation and conclusions contained herein are those of the researchers and do not necessarily represent the views of the Government of Alberta. Neither the Government of Alberta nor Alberta Health expresses any opinion in relation to this study.

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