Association of atrial fibrillation status with risk of strokes, mortality and cardiovascular outcomes in patients undergoing coronary artery bypass grafting.
TL;DR
This large retrospective observational study suggests AF status during CABG surgery is associated with a graded increase hospitalisation risk for ischaemic stroke/TIA, AF, HF and death.
Abstract
Background
Post-operative atrial fibrillation is a common complication following coronary-artery-bypass-grafting (CABG). Comparative outcome studies amongst patients following CABG with post-operative AF (POAF), pre-existing/background-AF, and no-AF are scarce.
Methods
Patients undergoing CABG between 1-January-2004 and 31-December-2017 were identified from a statewide Admitted-Patient-Data-Collection database. Patients <18yo or with concomitant cardiac valve surgery were excluded. Patients were stratified into no-AF, background-AF and POAF during index CABG using a look-back linkage methodology. Primary outcome was incidence of ischaemic stroke/transient-ischaemic-attack (TIA) requiring hospitalisation. Secondary outcomes included all-cause mortality and hospitalisation with AF, heart failure (HF), haemorrhagic stroke. Competing risk and Cox regression methods were used to assess risk for cardiovascular endpoints and death respectively.
Results
Among 46032 patients, 8.0% had background-AF, 27.4% developed new-onset POAF during index CABG and 64.7% had no-AF. During follow-up (median 6.6 years), POAF was associated with increased risk of hospitalisation for ischaemic stroke/TIA compared to no-AF cohort (adjusted subdistribution hazard ratio [adj.sHR]=1.14, 95% confidence interval [CI]=1.04-1.24, P=0.004). The risk appears greater in patients with background-AF (adj.sHR=1.41, 95%CI=1.25-1.60, P<0.001). A graded association was observed across AF groups with highest morbidities (AF and HF hospitalisations) and mortality risks post-CABG in background-AF patients followed by those with POAF, with no-AF cohort having lowest event rates.
Conclusions
This large retrospective observational study suggests AF status during CABG surgery is associated with a graded increase hospitalisation risk for ischaemic stroke/TIA, AF, HF and death. These findings highlight an under-recognised high-risk population and underscore need for renewed clinical focus on patients with pre-existing AF undergoing CABG.