Factors affecting death and progression towards next stage following modified Blalock-Taussig shunt in neonates.

Abstract

The modified Blalock-Taussig shunt (BTS) is utilized to palliate neonates born with restrictive pulmonary blood flow including those with single ventricle (SV) or biventricular (BV) cardiac anomalies. We aim in the current study to report palliation outcomes of neonates with BTS and to examine factors affecting death and progression to the subsequent stage of palliation or repair. Between 2002 and 2012, 341 patients underwent BTS including 175 with SV and 166 with BV anomalies. Competing risk analysis modelled events after BTS (death or transplantation, transition to Glenn shunt or biventricular repair) and examined risk factors affecting outcomes. SV patients had a higher incidence of extracorporeal membrane oxygenation (ECMO) support requirement (12 vs 4%, P = 0.004) and unplanned cardiac reoperation (14 vs 7%, P = 0.051) than their BV counterparts. Additionally, hospital mortality was higher in SV than in BV patients (15 vs 3%, P < 0.001). In SV patients, competing risk analysis showed that, 2 years following BTS, 27% of patients had died or received transplantation and 73% had undergone the Glenn shunt. On multivariable analysis, factors associated with time until death or transplantation prior to Glenn were cardiopulmonary bypass [hazard ratio (HR) 3.6 (2.0-6.4), P < 0.001], unplanned cardiac reoperation [HR 2.4 (1.3-4.6), P = 0.007], pulmonary atresia [HR 2.0 (1.1-3.7), P = 0.026] and the shunt size/weight ratio [HR 1.3 (1.1-1.4) per 0.1 increase, P = 0.001]. In BV patients, competing risk analysis showed that, 2 years following BTS, 13% of patients had died or received transplantation, 85% had undergone biventricular repair and 2% were alive without biventricular repair. On multivariable analysis, factors associated with time until death or transplantation prior to biventricular repair were genetic syndromes and extracardiac malformations [HR 6.1 (2.0-18.2), P = 0.001], weight ≤2.5 kg [HR 5.6 (2.0-16.0), P = 0.001] and male gender [HR 3.4 (1.1-11.0), P = 0.041]. Palliation with BTS continues to be associated with significant operative morbidity and mortality. In addition to hospital death, there is an important interstage attrition risk prior to subsequent palliation or biventricular repair. Inherent patient characteristics (i.e. genetic syndromes and low weight) and anatomical details (i.e. SV, pulmonary atresia and concomitant cardiac anomalies) are associated with worse survival.