The outcomes of patients with septic shock treated with propafenone compared to amiodarone for supraventricular arrhythmias are related to end-systolic left atrial volume

A recently published trial has shown no differences in outcomes between patients with new-onset supraventricular arrhythmia (SVA) in septic shock treated with either propafenone or amiodarone. However, these outcome data have not been evaluated in relation to the presence or absence of a dilated left atrium (LA).Patients with SVA and a left ventricular ejection fraction ≥35% were randomized to receive intravenous propafenone (70mg bolus followed by 400-840mg/24h) or amiodarone (300mg bolus followed by 600-1800mg/24h). They were divided into groups based on whether their end-systolic left atrial volume (LAVI) was ≥40 ml/m². The subgroup outcomes assessed were survival at ICU discharge, 1-month, 3-months, 6-months, and 12-months.Propafenone cardioverted earlier (p=0.009) and with fewer recurrences (p=0.001) in the patients without LA enlargement (n=133). Patients with LAVI˂40ml/m2 demonstrated a mortality benefit of propafenone over the follow up of 1-year (Cox regression, HR 0.6 (95% CI 0.4; 0.9), p=0.014). Patients with dilated LA (n=37) achieved rhythm control earlier in amiodarone (p=0.05) with similar rates of recurrences (p=0.5) compared to propafenone. The outcomes for patients with LAVI≥40 ml/m2 were less favourable with propafenone compared to amiodarone at 1-month (HR 3.6 (95% CI 1.03; 12.5), p=0.045) however, it did not reach statistical significance at 1 year (HR 1.9 (95% CI 0.8; 4.4), p=0.138).Patients with non-dilated LA who achieved rhythm control with propafenone in the setting of septic shock had better short-term and long-term outcomes than those treated with amiodarone, which seemed to be more effective in patients with LAVI≥40 ml/m².ClinicalTrials.gov Identifier: NCT03029169, registered on 24th of January 2017.