Abstract Body (Do not enter title and authors here): Introduction:
Heterotaxy syndrome (HS) manifests in varying degrees, involving abnormal left and right thoraco-abdominal organ distribution and frequently associated with congenital heart disease (CHD). More patients with CHD and HS are reaching adulthood, but limited data about survival and other clinical characteristics remain.

Research Question:
What are the demographics, survival rate, and comorbid complications of adult patients with CHD and HS?

Methods:
This is a single-center, retrospective chart analysis of all patients with CHD, HS, and follow-up at 18 years. Statistical methods included medians with interquartile ranges, Chi-Square, Fisher’s Exact Test, and Kaplan Meier analysis.

Results:
Ninety patients met inclusion criteria. Median age was 26.3 [21.9-31.5] years. Baseline demographics revealed 37 (41%) patients were female, 44 (49%) patients were Caucasian, 31 (34%) patients were Hispanic, 12 (13%) patients were Black, 2 (2%) patients were Asian, and 1 (1%) patient did not report their race. The median BMI was 22.7 [22.3, 32.5], with 16 patients (17%) having a BMI>30. Between the types of heterotaxy, 33 (37%) patients had polysplenia, 39 (43%) patients had asplenia, and 16 (18%) patients had situs ambiguous or situs inversus. Median follow-up time was 8.3 [4.3, 14.7] years. Forty-nine (54%) patients had single ventricle heart disease, of whom 37 (76%) completed Fontan palliation. Thirty-seven patients (41%) developed heart failure. Eighteen (20.7%) had a cerebral vascular accident, and 24 (30.8%) were arrhythmia free. Seventeen (19%) patients had a gap of care > 3 years since last follow-up. Fifty-two (58%) individuals were alive and with follow-up within 3 years of data collection. Four patients received orthotopic heart transplant (OHT), 3 of whom passed away, and 1 followed up elsewhere. Of the patients who died or received heart transplant, the median age was 26.7 [21.9-31.5] years. There was no statistically significant difference in survival or status of follow-up by type of heterotaxy (p=0.1), single ventricle versus double ventricle (p=0.9), presence of Fontan circulation (p=0.2), gender (p=0.9), or race (p=0.3). Figure 1 shows the overall survival curve.

Conclusion:
Patients with CHD and HS can survive childhood, but many may face significant related comorbidities, death, and OHT. These findings build on prior work and underscore the need for multi-institutional research efforts to improve outcomes in this complex patient population.