Use of Hybrid Stage I to Stratify Between Single Ventricle Palliation and Biventricular Repair

<b>Background:</b> Hybrid stage I palliation (HS1P) has been utilized for patients with single ventricle (SV) congenital heart disease (CHD). To date, reports on the use of HS1P for other indications including biventricular (BiV) CHD have been limited. <b>Methods:</b> We performed a single-center retrospective cohort study of patients who underwent HS1P with an anticipated physiologic outcome of BiV repair, or with an undetermined SV versus BiV outcome. Patient characteristics and outcomes from birth through definitive repair or palliation were collected and reported with descriptive statistics. <b>Results:</b> Nineteen patients underwent HS1P with anticipated BiV repair. Extracardiac and intracardiac risk factors (ICRF) were common. Ultimately, 13 (68%) patients underwent BiV repair, 1 (5%) underwent SV palliation, and 5 (26%) died prior to further palliation or repair. Resolution of ICRF tracked with BiV outcome (6/6, 100%), persistence of ICRF tracked with SV outcome or death (3/3, 100%). Twenty patients underwent HS1P with an undetermined outcome. Ultimately, 13 (65%) underwent BiV repair, 6 (30%) underwent SV palliation, and 1 (5%) underwent transplant. There were no deaths. Intracardiac risk factors were present in 15 of 20 patients (75%); BiV repair only occurred when all ICRF resolved (67%). Post-HS1P complications and reinterventions occurred frequently in both groups, through all phases of care. <b>Conclusions:</b> Hybrid stage 1 palliation can be used to defer BiV repair and to delay decision between SV palliation and BiV repair. Resolution of ICRF was associated with ultimate outcome. In this high-risk group, complications are common, and mortality especially in the marginal BiV patient is high.