Active management of atrial fibrillation or flutter in emergency department patients with renal impairment is associated with a higher risk of adverse events and treatment failure.

Objective: Atrial fibrillation or flutter (AFF) patients with renal impairment have poor long-term prognosis, but their emergency department (ED) management has not been described. We investigated the association of renal impairment upon outcomes after rate or rhythm control (RRC) including ED-based adverse events (AE) and treatment failure.

Methods: This cohort study used an electrocardiogram database from two urban centres to identify consecutive AFF patients and reviewed charts to obtain comorbidities, ED management, including RRC, prespecified AE, and treatment failure. Patients were dichotomized into a normal estimated glomerular filtration rate (eGFR) > 60 mL/min/1.73 m2) or impaired renal function ("low eGFR"). Primary and secondary outcomes were prespecified AEs and treatment failure, respectively. We calculated 1) adjusted excess AE risk for patients with decreased renal function receiving RRC; and 2) adjusted odds ratio of RRC treatment failure.

Results: Of 1,112 consecutive ED AFF patients, 412 (37.0%) had a low eGFR. Crude AE rates for RRC were 27/238 (11.3%) for patients with normal renal function and 26/103 (25.2%) for patients with low eGFR. For patients with low eGFR receiving RRC, adjusted excess AE risk was 13.7%. (95% CI 1.7 to 25.1%). For patients with low eGFR, adjusted odds ratio for RRC failure was 3.07. (95% CI 1.74 to 5.43) CONCLUSIONS: In this cohort of ED AFF patients receiving RRC, those with low eGFR had significantly increased adjusted excess risk of AE compared with patients with normal renal function. Odds of treatment failure were also significantly increased.