Congenital heart defects (CHDs) are a heterogeneous group of rare diseases of varying severity, each diagnosis with its unique set of co-morbidities. In addition to the heterogeneity, perhaps the greatest challenge to conducting comparative effectiveness research in CHD patients are the poor rates of successful transition from pediatric to adult centered cardiology care and high rates of gaps in recommend care for adults with CHD.

This study will use PCORnet to examine the effects of gaps in recommended care (cardiology visits) on patient prioritized outcomes for adults with non-complex and complex subtypes of CHD. This system will be established through 14 (12 recruiting) PCORnet affiliated institutions and linkage to the Congenital Heart Initiative registry (https://chi.eurekaplatform.org), the first patient powered registry for adults with CHD. This registry launched in December 2020, and is IRB approved at Children's National Hospital (IRB# Pro00014697). Funded by PCORI, this project will recruit patients at the 12 PCORnet affiliated institutions and will invite them to contribute their health records data and then join the established Congenital Heart Initiative.

By enrolling patients and linking their PCORnet (health record) data into an existing adult congenital heart disease (ACHD) specific registry, future interventions to reduce gaps in care based on study findings can be rapidly implemented in real-world settings through the strong partnerships established with key CHD stakeholders.

ACHD Surveillance Program/Observational Cohort (Aim 1 and Aim 2): To investigate the first two aims of this proposal, the study investigators will design and analyze an observational cohort of subjects >18 years of age with CHD from 14 PCORnet sites. Data is collected retrospectively (5 years prior to initial data query). Each subject with a diagnosis of CHD, > 18 years of age, and at least 1-3 years of retrospective information will be included in the study. Retrospective data will be obtained from the previous 1-3 years to ascertain adherence to recommended care by the ACC/AHA, specific to CHD subtype. Retrospective data collection will be to 1-3 years, with 2 years likely being sufficient to identify our patient cohorts. The investigators will still perform a retrospective data search for 5 years, but will not exclude patients if they do not have data sets for the full five year period.

The study team will specifically investigate frequency of gaps in recommended cardiology follow-up. Gaps in recommended care will be determined by the individual subtype of disease. The investigators will also examine advanced testing and imaging, but that will not be the primary measure of adherence to recommended care. In this cohort, the main outcomes of interest are key comorbidities and healthcare utilization. The investigators will be performing 2 cycles of data searches (March 2022 and January 2024), including the initial search for one year of follow-up after the subject's last cardiology visit.

Of note, with the COVID-19 pandemic, healthcare utilization has been affected throughout the population, not just those patients with rare diseases. To mitigate some of these issues, the study investigators will institute the following. For the data pertaining to the proposed study of loss to care, the retrospective data search in January 2020 (pre-COVID19) will be used and adjusted for lesion follow-up as described. Given the unique circumstances, the study investigators do feel that obtaining data during the COVID-19 pandemic is extremely important for this patient population, especially to identify the factors that might make some patients more vulnerable to loss to follow-up. Therefore, study investigators will analyze the retrospective data from February 2020 - June 2021 as a separate cohort in order to better identify the effects of the pandemic on this population of patients. Many centers (including all within the proposed study) began implementing telehealth visits, and will include this in the data capture.

Prospective cohort through CHI registry linkage (Aim 3): To investigate the third aim of the study, study investigators will design and analyze a prospective cohort design with the goal of establishing a diverse panel of CHD patients who are either (1) adhering or (2) not adhering to recommended care guidelines. Patients with qualifying CHD (ICD9/10 codes) who are > 18 years of age will be included in the study. Once patients are identified, site-specific PIs and their teams will facilitate enrollment into the Congenital Heart Initiative registry through the Eureka Research Platform with an electronic patient recruitment and engagement platform used with several large research projects. Specifically, patient prioritized outcomes (quality of life, mental health, and physical health & functioning) will be assessed among registrants who will be stratified by disease complexity and gaps in care.

Inclusion Criteria:

For Aims 1 & 2, participants will be deemed eligible to participate if they meet the following criteria:

• Age greater than or equal to 18 years at the time of initial data query
• Diagnosis of Congenital Heart Disease with at least one inpatient, outpatient, or emergency room visit within 8 years prior to the time of the initial data query
• Retrospective data available for 1-3 years prior to initial data query

For Aim 3, participants will be deemed eligible to participate if they meet the following criteria:

• Age greater than or equal to18 years at the time of initial data query
• Diagnosis of Congenital Heart Disease with at least one inpatient, outpatient, or emergency room visit within 6 years prior to the time of the initial data query
• Contact Information (email, address, and/or phone number)
• Email access through internet connected device or smartphone (Android or iOS)
• Can read/write English well enough to fill out on-line surveys

Exclusion Criteria:

• Age < 18 years
• No Congenital Heart Disease (as classified by ICD9/10 codes)

Study population will include Adults including Pregnant women

Individual Participant data will not be shared with other researchers.