Impact of atrial fibrillation on clinical outcomes in 28,492 patients following open-heart cardiac valve surgery: A statewide population-linkage study

BACKGROUND: Atrial fibrillation (AF) is common after cardiac surgery. Few studies compared clinical outcomes associated with AF between patients undergoing aortic valve surgery (AVSx) versus mitral valve surgery (MVSx). METHODS: Patients who had open-heart cardiac valve surgery (1- July-2003 to 31-March-2021) identified from the Admitted-Patient-Data-Collection database in Australia were stratified by AF status (No-AF vs. New-AF vs. Prior-AF during index valve surgery) and followed up to 31-March-2022. Multivariable Cox regression and Fine-Gray competing risk analyses were performed to assess the association of AF status on all-cause mortality and non-fatal outcomes respectively. RESULTS: The cohort comprised 28,492 patients (whole cohort median age 71.6yrs [interquartile range 62.7-78.3yrs]; 65.6% males): AVSx, n = 18,949, median age 73.3 [IR 65.4-79.4yrs], 67.8% males; MVSx, n = 9543, MVSx: median age 67.6 [IR 58.2-75.5yrs], 61.2% males. During a median 6.58yrs (3.4-10.5yrs) follow-up, Prior-AF and New-AF patients had significantly higher all-cause mortality (AVSx-Prior-AF: 57.9% vs. AVSx-New-AF: 41.5% vs. AVSx-No-AF: 32.8%; MVSx-Prior-AF: 41.0% vs. MVSx-New-AF: 29.8% vs. MVSx-No-AF: 22.4%) (both logrank P < 0.001). In the AVSx subgroup, both New-AF and Prior-AF were independently associated with all-cause mortality (aHR = 1.16, 95%CI = 1.10-1.22; aHR = 1.69, 95%CI = 1.59-1.79 respectively) compared to No-AF patients. In the MVSx subgroup, only Prior-AF was associated with increased all-cause mortality (aHR = 1.47, 95% CI = 1.33-1.61), all P < 0.001. Ischaemic stroke was significantly higher in the AVSx New-AF and AVSx-Prior-AF subgroups. CONCLUSIONS: Patients undergoing valve surgery have different risks of adverse clinical outcomes, with target valve and baseline AF status being associated with these outcomes.