Impact of Digoxin Use on Interstage Outcomes of Single Ventricle Heart Disease (From a NPC-QIC Registry Analysis)

Digoxin has been associated with lower interstage mortality (ISM) following stage 1 palliation (S1P). Despite a substantial increase in digoxin use nationally, ISM has not declined. We aimed to determine the impact of digoxin on ISM in the current era. This study analyzed data from the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) registry. All patients who survived to hospital discharge following S1P were included. Comparisons were made between pre-specified eras (1: 2010-2015, 2: 2016-2019) based on digoxin use. ISM risk was estimated using the previously published NEONATE score (excluding digoxin). Multivariable Cox proportional hazard models assessed the impact of digoxin on ISM and freedom from unplanned readmission in era 2. A total of 1400 (46.8%) patients were included from era 1 and 1589 (53.2%) from era 2. Digoxin use (22.4% vs 61.7%, p < 0.001) and the proportion of high-risk patients (9.1% vs 20.3%, p < 0.001) increased across eras. There was no difference in predicted ISM risk between those who did vs did not receive digoxin in era 2 (p = 0.82). In era 2, digoxin use was independently associated with lower ISM (AHR 0.60, 95%CI 0.36 to 0.98, p = 0.043) and greater freedom from unplanned readmission (AHR 0.44, 95%CI 0.32 - 0.59, p < 0.001). In conclusion, digoxin is independently associated with lower ISM and greater freedom from interstage readmission. The lack of improvement in overall ISM in the current era may be secondary to a greater proportion of high-risk patients and/or disproportionately higher digoxin use in lower risk patients, who may not derive the same benefit.