Dataset Information

Long-term Thromboembolic Risk in Patients With Postoperative Atrial Fibrillation After Coronary Artery Bypass Graft Surgery and Patients With Nonvalvular Atrial Fibrillation.

ABSTRACT:

Importance

New-onset postoperative atrial fibrillation (POAF) is a common complication of coronary artery bypass graft (CABG) surgery. However, the long-term risk of thromboembolism in patients who develop POAF after CABG surgery remains unknown. In addition, information on stroke prophylaxis in this setting is lacking.

Objective

To examine stroke prophylaxis and the long-term risk of thromboembolism in patients with new-onset POAF after first-time isolated CABG surgery compared with patients with nonsurgical, nonvalvular atrial fibrillation (NVAF).

Design, setting, and participants

This cohort study used data from a clinical cardiac surgery database and Danish nationwide registries to identify patients undergoing first-time isolated CABG surgery who developed new-onset POAF from January 1, 2000, through June 30, 2015. These patients were matched by age, sex, CHA2DS2-VASc score, and year of diagnosis to patients with nonsurgical NVAF in a 1 to 4 ratio. Data analysis was completed from February 2017 to January 2018.

Main outcomes and measures

The proportion of patients initiating oral anticoagulation therapy within 30 days and the rates of thromboembolism.

Results

A total of 2108 patients who developed POAF after CABG surgery were matched with 8432 patients with NVAF. In the full population of 10 540 patients, the median (interquartile range) age was 69.2 (63.7-74.7) years; 8675 patients (82.3%) were men. Oral anticoagulation therapy was initiated within 30 days postdischarge in 175 patients with POAF (8.4%) and 3549 patients with NVAF (42.9%). The risk of thromboembolism was lower in the POAF group than in the NVAF group (18.3 vs 29.7 events per 1000 person-years; adjusted hazard ratio [HR], 0.67; 95% CI, 0.55-0.81; P < .001). Anticoagulation therapy during follow-up was associated with a lower risk of thromboembolic events in both patients with POAF (adjusted HR, 0.55; 95% CI, 0.32-0.95; P = .03) and NVAF (adjusted HR, 0.59; 95% CI, 0.51-0.68; P < .001) compared with patients who did not receive any anticoagulation therapy. Further, the risk of thromboembolism was not significantly higher in patients with POAF compared with those who did not develop POAF after CABG surgery (adjusted HR, 1.11; 95% CI, 0.94-1.32; P < .24).

Conclusions and relevance

New-onset POAF in patients who had undergone CABG surgery was associated with a lower long-term thromboembolic risk than that of patients who had NVAF. These data do not support the notion that new-onset POAF should be regarded as equivalent to primary NVAF in terms of long-term thromboembolic risk.

SUBMITTER: Butt JH

PROVIDER: S-EPMC5875315 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background The CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes, previous stroke or TIA [transient ischemic attack], vascular disease, age 65 to 74 years, sex category female; 2 indicates 2 points, otherwise 1 point) scoring system is recommended to guide decisions on oral anticoagulation therapy for stroke prevention in patients with nonsurgery atrial fibrillation. A score ≥1 in men and ≥2 in women, corresponding to an annual stroke risk exceeding 1%, warrants long-term oral anticoagulation provided the bleeding risk is acceptable. However, in patients with new-onset postoperative atrial fibrillation, the optimal risk stratification method is unknown. The aim of this study was therefore to evaluate the CHA2DS2-VASc scoring system for estimating the 1-year ischemic stroke risk in patients with new-onset postoperative atrial fibrillation after coronary artery bypass grafting. Methods and Results All patients with new-onset postoperative atrial fibrillation and without oral anticoagulation after first-time isolated coronary artery bypass grafting performed in Sweden during 2007 to 2017 were eligible for this registry-based observational cohort study. The 1-year ischemic stroke rate at each step of the CHA2DS2-VASc score was estimated using a Kaplan-Meier estimator. Of the 6368 patients included (mean age, 69.9 years; 81% men), >97% were treated with antiplatelet drugs. There were 147 ischemic strokes during the first year of follow-up. The ischemic stroke rate at 1 year was 0.3%, 0.7%, and 1.5% in patients with CHA2DS2-VASc scores of 1, 2, and 3, respectively, and ≥2.3% in patients with a score ≥4. A sensitivity analysis, with the inclusion of patients on anticoagulants, was performed and supported the primary results. Conclusions Patients with new-onset atrial fibrillation after coronary artery bypass grafting and a CHA2DS2-VASc score <3 have such a low 1-year risk for ischemic stroke that oral anticoagulation therapy should probably be avoided.

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