Lower Survival After Coronary Artery Bypass in Patients Who Had Atrial Fibrillation Missed by Widely Used Definitions

Area of Science:

• Cardiology
• Cardiac Surgery
• Clinical Research

Background:

• Post-coronary artery bypass graft (CABG) atrial fibrillation (AF) is a common complication.
• The Society of Thoracic Surgeons (STS) database defines post-CABG AF as treated AF/flutter, potentially leading to undercounting.
• Accurate identification of post-CABG AF is crucial for understanding its impact on patient survival.

Purpose of the Study:

• To investigate the impact of a limited definition of post-CABG AF on its association with survival.
• To compare survival rates between patients with post-CABG AF identified in STS data versus those not identified but detected via continuous monitoring.
• To evaluate the reliability of STS data for research on post-CABG AF and survival.

Main Methods:

• A cohort of 7110 isolated CABG patients without preoperative AF was analyzed.
• Patients were grouped based on whether post-CABG AF was identified in STS data (Group 1), not identified in STS data but detected by monitoring (Group 2), or had no documented AF (Group 3).
• Survival was compared using a Cox model, adjusted for STS risk of mortality and accounting for hospital site.

Main Results:

• Over 7 years, mortality rates were 16.0% (Group 1), 18.7% (Group 2), and 7.9% (Group 3).
• Group 2 (AF missed by STS) had a significantly higher adjusted risk of death compared to both Group 1 (HR 1.16) and Group 3 (HR 1.94).
• The findings indicate a 16% higher risk of death for patients whose post-CABG AF was missed by STS data.

Conclusions:

• The STS database's definition of post-CABG AF leads to misclassification and weakens the observed association with survival.
• Differences in treatment and post-discharge management for 'missed' AF cases warrant further investigation.
• STS data should not be used for research examining post-CABG AF due to its limitations in accurately capturing AF events.