Very low 30-day mortality can give false sense of complacency in arterial switch ops
Children with a heart defect called transposition of great arteries (TGA) are born with the two major blood vessels (aorta and the main lung artery) arising from the wrong sides of the heart. Consequently, blood is pumping inappropriately between the lungs and the rest of the body, a fatal condition unless surgically treated. The surgery of choice, the arterial switch operation (ASO), is usually performed within the first few weeks of life. In a retrospective analysis of 30 years of experience performing ASOs, Hanna A. Jensen, MD, PhD, and the rest of the team led by Victor Tsang, MD, FRCS, from the Great Ormond Street Hospital for Children NHS Foundation Trust in London, suggest that 90-day outcomes may give a more revealing picture than the traditional reliance on 30-day data. She is presenting the results of this research at the 94th AATS Annual Meeting in Toronto.
ASO was introduced in the late 1970s. Initially this delicate operation on small infants was associated with a high risk of early death following surgery. As experience of surgeons and other professionals in the care teams has evolved, the risk of early death has significantly decreased worldwide. Today approximately 96% of TGA patients in the United Kingdom survive the first 30 days after ASO.
Thirty-day mortality (the percentage of patients who die within 30 days after a specific operation) is traditionally used as an outcome measure for monitoring the results of a surgical unit or comparing surgical programs. However, Dr. Jensen and colleagues hypothesized that in the current clinical setting, the tracking and reporting of only 30-day mortality may be falsely reassuring. "Modern-day intensive care, technology, and life support immediately after surgery have evolved hand-in-hand with the surgical profession, and patients today can be extensively rescued and their circulation mechanically supported, for possible recovery over a longer timeframe," explains Dr. Jensen.
In this retrospective study, the investigators conducted an analysis of all TGA patients who underwent ASO at the Great Ormond Street Hospital for Children between 1983 and 2012. The 30 years of data were divided into three 10-year eras. They not only recorded all patients who died within the first 30 days after the operation, but also those who succumbed between 30 and 90 days after ASO. They identified 606 operations and found that the 30-day mortality clearly decreased over time, from 23% in 1982-1992 (Era 1), to 6% in 1993-2002 (Era 2), and then to 1% in 2003-2012 (Era 3).
The percentage of patients who died between 30 and 90 days, however, showed more modest signs of change, as the 30-to-90 day mortality was 3%, 3%, and 2% in the respective eras. In Era 3, for the first time, more patients died between 30 and 90 days than in the first 30 days (6 vs. 3). Of the operative or intensive care strategies, implementation of a technology called extracorporeal membrane oxygenation (ECMO) was significantly associated with early death in the most recent era studied (2003-2012). ECMO was chosen as a "near miss" variable – enabling the monitoring and tracking not only of high-risk patients who died, but also those who came close to dying. During those years, the investigators found 26 patients who required ECMO, 58% of whom died within 90 days. During Era 1 (1983-1992), having to re-establish cardiopulmonary bypass was considered a "near miss."
"Despite the current excellent 30-day outcome following ASO, there is no room for complacency; our data suggests that the early, risky phase of the operation is being extended," says Dr. Jensen. The study found that 18 patients in the 30-year cohort died after 30 days but before 90 days. Many of these babies died after having been discharged from the hospital. Dr. Jensen suggests that the 30-day target for monitoring and reporting should be reconsidered to reflect the realities of modern-day care, so that patients' families can be better informed. Defining and monitoring a "near miss" variable within a surgical unit can enhance quality assurance and allows the identification of "rescued" patients for closer observation and proactive management.