Atrial fibrillation as a sentinel cardiovascular event in renal cell carcinoma hospitalizations: National Inpatient outcomes and rescue failure (NIS 2016–2023).

e23226 Background: Cardiovascular instability is common during renal cell carcinoma (RCC) hospitalizations, yet atrial fibrillation (AF) is often treated as incidental. This study reframes AF as a sentinel inpatient event that may identify early physiologic decompensation and worse rescue outcomes in RCC. Methods: A survey-weighted analysis of the 2016–2023 National Inpatient Sample was performed. Adult RCC hospitalizations were identified by diagnosis codes. AF phenotypes were defined as no AF, secondary AF (AF present but not the principal diagnosis), or AF-primary (AF as the principal diagnosis). Outcomes included in-hospital mortality, ICU-level care proxy (mechanical ventilation, dialysis, or shock), major complications (sepsis, acute kidney injury, respiratory failure, shock, ventilation, or dialysis), failure-to-rescue (death among admissions with major complications), length of stay (LOS), and costs/charges. Multivariable survey-weighted regression adjusted for demographics, payer, income quartile, weekend admission, admission acuity, hospital characteristics, and year. Results: Among an estimated 733,705 RCC hospitalizations nationally, AF was present in 15.6%, including 15.0% secondary AF and 0.63% AF-primary. Outcomes differed markedly by AF phenotype. Mortality was 3.31% with no AF, 6.57% with secondary AF, and 2.38% with AF-primary. ICU-level care occurred in 7.57% with no AF versus 14.47% with secondary AF (AF-primary 7.78%). Major complications occurred in 36.1% with no AF versus 56.7% with secondary AF (AF-primary 37.0%). Failure-to-rescue among admissions with major complications was 7.66% with no AF and 10.62% with secondary AF (AF-primary 5.26%). Mean LOS was longer with secondary AF (6.83 vs 4.95 days), with higher mean costs ($26,261 vs $22,489) and charges ($90,907 vs $77,612). In adjusted analyses, secondary AF was independently associated with higher mortality (aOR 1.54, 95% CI 1.43–1.66), ICU-level care (aOR 1.96, 95% CI 1.85–2.06), major complications (aOR 1.66, 95% CI 1.60–1.72), and failure-to-rescue (aOR 1.41, 95% CI 1.30–1.53), each compared with no AF. AF-primary was associated with lower adjusted mortality (aOR 0.41, 95% CI 0.26–0.67) and fewer major complications (aOR 0.53, 95% CI 0.45–0.61) versus no AF. Conclusions: In RCC hospitalizations, AF is common and heterogeneous. Secondary AF identifies a high-risk inpatient phenotype with substantially higher mortality, ICU escalation, major complications, and failure-to-rescue, consistent with AF as a sentinel marker of acute systemic stress rather than an incidental comorbidity.