Abstract Body (Do not enter title and authors here): Introduction: Despite the growing number of patients (pts) with CHD, US population-wide data on mortality rates (MR) and causes of death (COD) remain limited. We describe the modern MRs and COD across lifespan by CHD severity from the largest population-based US study of CHD pts to date.

Methods: STAR1 is a US population-based study of CHD pts (except isolated secundum ASD/PFO) ages 0-45 years old (yo) from 7 states with ≥1 health care encounters from 2010-2019. Age at death and underlying COD (UCOD) were captured from state death certificates or birth defect registry. COD subgroups included: CHD, heart failure (HF), cardiovascular disease (CAD, MI, stroke), other acquired CV disease and non-cardiac disease. MRs were calculated as deaths per 100k live births in infants (<1 yo), and deaths per 100k person-years in non-infants to account for varying follow up times. Non-severe (nsCHD; shunts or valve only lesions) and severe CHD (sevCHD; e.g. single ventricle, cyanotic CHD) were compared.

Results: Of the 218,863 pts, 21% had sevCHD. In the sevCHD and nsCHD cohorts, 43% and 52% were infants at study entry. Over the study period 7,175 pts died (3.2%), of whom 48% had sevCHD; 7.6% with sevCHD died versus 2.1% with nsCHD. A total of 11% of sevCHD and 2% of nsCHD infants died, accounting for 60% and 55% of all deaths in each severity group (infant MR sevCHD = 11,715, nsCHD=2,222 per 100k, p<0.05). MR was consistently lower across the lifespan for nsCHD vs sevCHD (Figure 1). UCOD was available in 3/7 states, including 40% of sevCHD and 41% of nsCHD deaths. Figure 2 shows the UCOD by age group and severity. In sevCHD, most UCOD were cardiac, mainly CHD in younger pts and a combination of CHD and all acquired CVD with increasing age. By 41+ yo, acquired CVD and CHD each accounted for approximately 40% of overall MR. HF was the most common single non-CHD cardiac UCOD, increasing from 9/100k in 11-20 yo to 197 in 41+ yo (p < 0.05). Though uncommon, CHD was an UCOD across all nsCHD ages. Non-cardiac disease in those with nsCHD was the most common UCOD until 30 yo versus all acquired CVD > 30 yo.

Conclusion: Mortality is highest in infancy for both sevCHD and nsCHD. SevCHD has uniformly higher MR than nsCHD, and death is commonly cardiac in nature across the lifespan. CHD and acquired CVD were the UCOD in 80% pts > 40 years of age, highlighting the need for specialized CHD care and an emphasis on CV preventive care throughout the lives of CHD pts.