(1476) Impact of Norepinephrine to Phenylephrine Transition on Atrial Fibrillation Management in Sepsis

Introduction: New onset atrial fibrillation is common in sepsis. Norepinephrine, the first-line vasopressor for septic shock, can cause tachyarrhythmias. Limited data suggests switching norepinephrine to phenylephrine may decrease heart rate and improve rate control. This study compared the effect of this vasopressor transition on clinical interventions for rate control in septic patients who developed atrial fibrillation on norepinephrine.

Methods: A single-center, retrospective cohort study of septic shock patients admitted to the medical and surgical intensive care units at UMass Memorial Medical Center from January 1, 2018 to September 1, 2022 was performed. Patients were included if atrial fibrillation with rapid ventricular response developed on norepinephrine. Major exclusion criteria included receiving inotropes or vasopressors other than norepinephrine, vasopressin, and phenylephrine or diagnosis of non-septic shock syndromes. Patients switched to phenylephrine were compared to those who remained on norepinephrine. The primary composite outcome was initiation of a new rate/rhythm control agent, increased dose of home rate/rhythm control agent, or direct cardioversion.

Results: A total of 1329 patients were screened, with 75 patients included in each group. The primary composite outcome occurred in 61% of phenylephrine patients compared to 87% of norepinephrine patients (p = 0.001). Rate/rhythm control agents were initiated less often for those on phenylephrine compared to norepinephrine (60% vs. 79%; p = 0.01). Phenylephrine patients had a longer total duration of vasopressor therapy (108 vs. 51 hours; p = 0.001). No significant differences were seen in all other secondary and safety outcomes, including 28-day mortality, time to and proportion of time with rate control, and ICU and hospital length of stay.

Conclusions: In ICU patients with septic shock that developed atrial fibrillation on norepinephrine, switching vasopressor therapy to phenylephrine reduced rates of clinical interventions required for rate control. It is unknown if switching to phenylephrine impacts overall patient outcomes compared to remaining on norepinephrine and potentially requiring more interventions for atrial fibrillation.