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Improving early outcomes following hybrid procedure for patients with single ventricle and systemic outflow obstruction: defining risk factors†.

OBJECTIVES
The hybrid procedure has become an accepted management strategy for patients with single ventricle and systemic outflow obstruction (SVSOO), particularly those considered at high risk for mortality following Stage I Norwood. We sought to refine patient selection by identifying clinical variables associated with early mortality.


METHODS
Single-centre review of all patients with SVSOO undergoing a hybrid procedure between January 2003 and December 2012. Demographic, clinical and outcome data were collected from the electronic medical record. The primary outcome was operative mortality (mortality within 30 days of the operation or prior to hospital discharge).


RESULTS
Thirty-four patients underwent hybrid palliation at a median age of 5 days (IQR 3-8.5) and a median weight of 2.5 kg (IQR 2.2-2.9). Aortic atresia was present in 13 of 34 patients. Emergency banding for resuscitation was performed in 8 cases. Subsequent procedures included Stage I Norwood in 14, combined Stage I and II Norwood in 8, biventricular repair in 3 and cardiac transplantation in 2. Median cardiac intensive care unit length of stay was 54 days (IQR 27-92). Seven patients had no subsequent procedure. There were 11 operative deaths. Non-modifiable patient-related factors had a significant association with operative mortality, including weight under 2.0 kg (OR 18; 95% CI 1.8-188.3, P = 0.0008) and aortic atresia (OR 6.1; 95% CI 1.2-30.1, P = 0.026). Most significant was the interaction between aortic atresia and weight under 2.0 kg on early mortality (OR 13.1; 95% CI 1.9-92 P = 0.0039). The multivariate analysis demonstrated that the presence of aortic atresia (OR 13.4; 95% CI 1.2-151) and a birthweight of 2.0 kg or less (OR 51; 95% CI 2.4-999) were also significant predictors of operative mortality.


CONCLUSIONS
Non-modifiable patient-related factors have a profound effect on early survival following a hybrid procedure for SVSOO. Outcomes for patients under 2.0 kg with aortic atresia remain very poor. Risk stratification should inform management decisions.