New-onset atrial fibrillation or flutter during the ICU stay and mortality in patients with sepsis-associated myocardial injury: a time-varying cohort study.

BACKGROUND: New-onset atrial fibrillation or flutter (NOAF) is common during sepsis, but its prognostic significance in sepsis-associated myocardial injury remains unclear. OBJECTIVES: We examined its association with mortality using a time-varying analytic approach and assessed whether this association differed by onset timing. METHODS: We conducted a single-centre retrospective cohort study of adult intensive care unit patients with coded sepsis and elevated high-sensitivity cardiac troponin T. Patients with pre-existing atrial fibrillation or atrial flutter were excluded. New-onset atrial fibrillation or flutter during the intensive care unit stay was modelled as a time-varying exposure in Cox models. Early onset was defined as within 48 h of intensive care unit admission and late onset as beyond 48 h. RESULTS: Among 599 patients, 125 developed new-onset atrial fibrillation or flutter. In the fully adjusted model, the time-varying exposure was associated with higher in-hospital mortality (hazard ratio 1.69, 95% confidence interval 1.14-2.52) and intensive care unit mortality (hazard ratio 1.70, 95% confidence interval 1.07-2.70). Late-onset events were associated with higher in-hospital and intensive care unit mortality, whereas early-onset events showed no clear association with either outcome. In landmark analysis, early-onset events were not associated with subsequent in-hospital mortality. CONCLUSION: NOAF during the ICU stay was associated with higher mortality in patients with sepsis-associated myocardial injury. Late-onset NOAF was associated with mortality, whereas early-onset NOAF showed no clear association.