Impact of atrial fibrillation on mortality and non-fatal cardiovascular outcomes in 152 638 patients admitted with congestive cardiac failure: a statewide population-linkage study

Abstract

Abstract Background Congestive cardiac failure (CCF) and atrial fibrillation (AF) frequently co-exist, cause and exacerbate each other. Prior studies on the impact of AF in CCF patients yielded mixed findings. Purpose This study aims to examine the impact of AF on long-term outcomes including MACE (major adverse cardiovascular events defined as all-cause mortality and major cardiovascular outcomes including myocardial infarction, ischaemic stroke, CCF or revascularization) and other non-fatal vascular or bleeding outcomes in patients admitted with CCF. Methods Hospitalised patients in New South Wales (NSW), the largest state of Australia, from 1 July 2003 to 31 March 2021 with a primary diagnosis of CCF were identified from the statewide Admitted-Patient-Data-Collection database, stratified by AF (Prior-AF or New-AF during index CCF admission) and No-AF status, with follow-up until 31 March 2022. A linkage look-back to year-2001 was performed to identify prior-AF history. In addition to MACE, non-fatal outcomes assessed included recurrent admission with AF, haemorrhagic stroke, peripheral arterial thromboembolism, pulmonary embolism, and bleeding. Multivariable Cox regression was performed to assess the impact of AF on MACE. To account for the competing risk of death and assess the impact of AF on non-fatal cardiovascular outcomes, Fine-Gray competing risk analysis was performed. Results The cohort comprised 152 638 admitted CCF patients (median age: 80.4 years; 51.4% males): New-AF, n=16 371 (10.7%); Prior-AF, n=56 546 (37.0%) (Table 1). During a median follow-up of 2.5 years, compared to No-AF CCF patients, those with New-AF or Prior-AF had significantly higher rates of MACE (New-AF: 81.7% vs Prior-AF: 86.3% vs No-AF: 78.5%) driven by all-cause mortality (New-AF: 71.6% vs Prior-AF: 76.5% vs No-AF: 66.2%) (both logrank P<0.001). However, after adjusting for differences in baseline characteristics and admission year-groups, New-AF and Prior-AF status had differential impact on MACE compared to No-AF patients (adjusted hazard ratio [aHR]=0.93, 95% confidence interval [CI]=0.91-0.94; aHR=1.14, 95%CI=1.13-1.16 respectively; both P<0.001). Results were similar for all-cause death (aHR=0.94 and aHR=1.16 respectively; both P<0.001). Competing risk analyses showed that rehospitalisation for ischaemic stroke, AF, haemorrhagic stroke, peripheral arterial thromboembolism and bleeding were significantly higher in CCF patients with New-AF and Prior-AF (P<0.001), after adjusting for age, sex, referral source, year-groups, intensive-care-unit admission and Charlson comorbidities index (Table 2). Conclusion This study shows that AF status has a differential impact on clinical outcomes in patients admitted with CCF. Drivers behind this difference in outcomes require further study and strategies should be developed to minimise the risk of adverse clinical outcomes in this vulnerable group of patients.Table 1.Baseline characteristicsTable 2.Non-fatal CV outcomes