Association of the pattern of new-onset post-operative atrial fibrillation with adverse clinical events over 1 year follow-up: insights from the VISION Cardiac Surgery Cohort

New-onset post-operative atrial fibrillation (AF) affects approximately 1 in 3 patients after cardiac surgery and is associated with adverse outcomes. Whether the amount of time spent in AF is associated with outcomes is unknown.

VISION Cardiac Surgery was an international, prospective cohort of patients who underwent cardiac surgery in 12 countries. We divided participants according to their pattern of AF: no new-onset AF, duration <24 h, duration 24-48 h, duration 48-72 h, duration >72 h and discharged in AF. We created a separate category for those who received electrical cardioversion. We excluded participants with a history of AF before surgery and participants with unknown duration of AF.

We assessed the association of different patterns of AF, as compared to no AF, with clinical events occurring between 30 days post-operatively and 1 year of follow up. For each outcome, we created a Cox proportional hazards model adjusted for CHA2DS2-VASc score, smoking, hemodialysis, prior cardiac surgery, surgery type and antithrombotic use at hospital discharge (oral anticoagulation alone, oral anticoagulation plus antiplatelet, antiplatelet alone, or none).

Among 12,234 eligible participants, 3,887 (30.3%) had new-onset post-operative AF and 3,711 had a known duration of AF. The proportion of patients with new-onset AF who were discharged from hospital on oral anticoagulation was 39%. Table 1 displays event rates by AF pattern. Compared to participants without AF, we observed a higher risk of a composite of stroke or vascular death at one year in participants with estimated AF duration >72 h (3.9%, adjusted hazard ratio (aHR) 1.72; 95% CI 1.03-2.87) and in those who underwent electrical cardioversion (3.7%, aHR 2.18; 95%CI 1.16-4.11). Only AF duration >72 h was associated with an increased risk of stroke (2.1%; aHR 2.42; 95%CI 1.15-5.09). We observed a higher risk of all-cause mortality in participants who were in AF at hospital discharge (4.1%, aHR 1.83; 95%CI 1.10-3.05) and in participants who received electrical cardioversion (5.8%, aHR 2.81; 95%CI 1.67-4.73). Only being in AF at discharge was associated with an increased risk of heart failure (3.8%; aHR 2.63; 95% CI 1.49-4.63). All patterns of AF were associated with AF detection in follow-up, with the strongest associations observed in participants who were in AF at hospital discharge (31.8%, aHR 73.4; 95%CI 51.4- 105.0) and in those who received electrical cardioversion (12.5%, aHR 17.9; 95%CI 11.1-28.8).

Among patients with new-onset post-operative AF following cardiac surgery, duration of AF >72 h, electrical cardioversion and being in AF at discharge are all markers of adverse events in the year following surgery. All patterns of AF confer a higher risk of AF detection in follow-up. Duration and treatment of early post-operative AF may have implications regarding the longer-term risk of adverse outcomes and recurrent AF.