Identified mortality risk factors associated with presentation, initial hospitalisation, and interstage period for the Norwood operation in a multi-centre registry: a report from the national pediatric cardiology-quality improvement collaborative.

Hypoplastic left heart syndrome remains A challenging diagnosis with substantial mortality risk. Families and healthcare mortality risk. Families and healthcare providers invest tremendous time and effort to ensure the likelihood of survival and well-being of children with such a diagnosis. Children with hypoplastic left heart syndrome typically undergo staged palliation; however, some centres favour the hybrid procedure or transplantation as the initial treatment for hypoplastic left heart syndrome.1-3 Despite improvements in pre-operative care, surgical technique, perfusion strategy, and post-operative cardiac intensive care, the mortality rate remains high. Reports of early Stage 1 mortality vary widely and are centre dependent, but recent reports suggest that nationally approximately one of every five patients undergoing the Norwood operation will not survive to hospital discharge.4-8 The time between the Stage 1 and Stage 2 operations, referred to as the interstage period, also continues to be a period of potential haemodynamic instability regardless of the surgical approach taken, with additional interstage mortality ranging from 4% to 15% for Stage 1 survivors.9-13 Some of the identified risk factors specific to interstage mortality have included hypoplastic left heart syndrome with intact or restrictive atrial septum, re-coarctation of the aortic arch, obstruction of the pulmonary arteries or shunt, age at operation >7 days, longer aortic cross-clamp time, and post-operative renal dysfunction.10,12,14,15 Other factors implicated in the overall mortality include lower pre-operative pH, smaller ascending aorta diameter, longer deep hypothermic circulatory arrest, severe right ventricular dysfunction, presence of significant tricuspid regurgitation, and higher incidence of airway or respiratory complications.10,16 Most of these reports have been either single centred, retrospective, or covered a long period of time during which multiple changes in the care of children with hypoplastic left heart syndrome could have been implemented. It has also been shown that there is wide variation in the management approach to patients in the interstage period, making generalisations about care and outcomes of this patient population difficult.17 The Joint Council on Congenital Heart Disease National Pediatric Cardiology-Quality Improvement Collaborative was created to promote wide-ranging improvements in congenital heart disease outcomes through the use of quality improvement science techniques and education, as well as development of national paediatric congenital heart disease data registries to monitor care delivery and outcomes. Details regarding the collaborative’s structure and composition are reported elsewhere.18,19 The first improvement effort chosen by the National Pediatric Cardiology-Quality Improvement Collaborative was to decrease interstage mortality following the Stage 1 operation. The key drivers of the improvement effort are focused on improving care transitions, achieving adequate growth, engaging parents, and improving care coordination among parents, cardiologists, and the primary care medical home.18,19 The associated multi-centre data registry focuses on many aspects of the initial hospitalisation and Stage 1 procedure, interstage hospitalisation and outpatient encounters, as well as the Stage 2 hospitalisation that are impacted by these key drivers. It is expected that the registry will enable practitioners to understand risk factors and outcomes associated with the management of these challenging patients. Owing to the paucity of multi-centre prospective data on the interstage period, we sought to identify risk factors of interstage mortality in the present era using the National Pediatric Cardiology-Quality Improvement Collaborative multi-centre data registry. The analysis was intended to be exploratory and hypothesis generating as opposed to hypothesis driven, with the goal of identifying potential risk factors documented in the registry that could lead to improvement in interstage management approaches. A secondary aim was to identify patient management issues that could call for immediate attention by the collaborative in the early phase of registry data collection.