Supplemental Data:
KID Database:
Data in the KID are stratified by geographic region, location/teaching status, bed size category, and whether the hospital is a freestanding children’s hospital. Discharges are also stratified by uncomplicated in-hospital births, complicated in-hospital births, and non-newborn pediatric discharges. Discharge weights are created for each stratum in proportion to the known number of American Hospital Association discharges nationally (Normal newborns were sampled at a rate of 10%, while complicated newborns and other pediatric discharges were sampled at a rate of 80%) and using the discharge weights, individual observations are extrapolated to produce national estimates . Prior to the KID 2016, diagnostic (CM) and procedural codes (PCS) were reported using the International Classification of Diseases, Ninth revision (ICD-9) codes and starting with 2016, the ICD-10-CM/PCS coding system was used .
Supraventricular arrhythmias such as atrial flutter/fibrillation codes were not included in the primary arrhythmia group. Heart transplant codes were included in the ‘Other’ category even if they had diagnoses of cardiomyopathy or arrhythmias. Since not all cardiomyopathy disorders are associated with systolic heart failure (example Hypertrophic Cardiomyopathy or Arrhythmogenic Cardiomyopathy), we did not assume that cardiomyopathy diagnostic categories were necessarily associated with heart failure. We therefore also explored the presence of heart failure, which for this study was defined by heart failure diagnostic codes or codes identifying the implantation or presence of mechanical support (Veno-arterial extracorporeal membrane oxygenation or Ventricular assist device). Codes for ICD infection, lead fracture, pneumothorax, hemothorax, mechanical complication of ICD or need for ICD-revision were used to define the composite variable of ICD complication. The primary outcome was in-hospital death.