<p><strong>BACKGROUND: </strong>The purpose of this study was to describe the prevalence, characteristics, and outcomes in pediatric patients with chromosomal anomalies (CA) undergoing orthotopic heart transplantation (OHT).</p>

<p><strong>METHODS: </strong>A query of the database of the Pediatric Health Information System, a large administrative and billing database of 43 tertiary children's hospitals, was performed for the Years 2004 to 2016. Pediatric patients who received OHT were analyzed based on presence and type of CA. CA analyzed included: Down syndrome (DS); Turner syndrome (TS)/gonadal dysgenesis; conditions due to anomaly of unspecified chromosome; autosomal deletion; microdeletion; and autosomal anomaly. Healthcare-associated charge analysis during hospitalization for OHT and survival after OHT were assessed.</p>

<p><strong>RESULTS: </strong>A total of 3,080 hospitalizations were identified in which OHTs were performed. Of these OHTs, 64 (2.1%) were performed in patients with a concomitant diagnosis of CA. The presence of CA did not confer a higher risk of in-hospital mortality after OHT (odds ratio 1.2 [0.5 to 3.2], p = 0.651). Differences in in-hospital mortality between different types of CA, including DS and TS, did not reach statistical significance. Survival at 1-year post-OHT was similar in patients with CA compared to those without CA (p = 0.248). Length of stay after OHT was longer in patients with CA: 76 (interquartile range [IQR] 76 to 142 days vs 49 [IQR 21 to 98] days) (p &lt; 0.001), respectively. Overall adjusted hospital charges were significantly higher in the CA group: $1.2 million (IQR $740,000 to $2.2 million) vs $792,000 (IQR $425,000 to $1.5 million] (p &lt; 0.001), respectively.</p>

<p><strong>CONCLUSIONS: </strong>CA is present in ~2% of pediatric patients undergoing OHT. The presence of CA was not associated with increased mortality in pediatric patients undergoing OHT. Limitations of this study include the small number of patients available for analysis and a likely highly selective cohort of patients with CA.</p>