Long-term outcomes of truncus arteriosus repair

Abstract

Truncus arteriosus is a rare congenital cardiac defect which results in a single common arterial trunk exiting the heart which supplies the systemic, pulmonary, and coronary circulations. The truncus itself is guarded by a single, often large common valve – the truncal valve – which separates the truncus from both the left and right ventricle. Truncus arteriosus has an incidence of 3 to 10 per 100,000 live births. Although only 0.7% – 3% of all congenital cardiac anomalies are due to truncus arteriosus, it accounts for 4% of all critical congenital cardiac anomalies. Patients typically present early in life with symptoms of cyanosis and congestive cardiac failure. Nowadays, surgery is undertaken early in life prior to the development of irreversible pulmonary hypertension. Improvements in surgical techniques and perioperative management has drastically reduced early mortality to 3 – 20%. Therefore, many children who have undergone truncus arteriosus repair are living well into adulthood. Despite this, there are few large studies addressing the long-term outcomes of truncus arteriosus repair. Furthermore, the impact of concomitant anomalies and the truncal valve are insufficiently described. This Doctor of Philosophy focuses on the long-term outcomes of truncus arteriosus repair in order to determine the current results and risk factors for poor outcomes. This research constitutes the largest single-institutional and multi-institutional experience assessing the long-term outcomes of truncus arteriosus repair with the longest follow-up time. I demonstrated that the majority of mortality following truncus arteriosus repair occurs within the first year after repair, and survival beyond the first year is excellent. I found that the presence of a coronary artery anomaly was associated with both early and late mortality and suggest that the coronary anatomy be clearly identified intraoperatively. Furthermore, patients with DiGeorge syndrome are at risk of late mortality, most commonly due to infection. Interestingly, I found that patients with mild or less truncal valve insufficiency are free from truncal valve surgery for up to 25 years, despite their truncal valve anatomy. In contrast, most patients with moderate or greater truncal valve insufficiency – particularly those with a quadricuspid truncal valve – will require truncal valve surgery at some stage in their lifetime. Of note however, the durability of truncal valve repair as a whole is poor, with most patients requiring reoperation on the truncal valve. In those with a quadricuspid truncal valve, repair by tricuspidization appears to be the most durable option with good long-term outcomes. Tricuspidization provided better long-term outcomes even if the non-tricuspidization group included younger children (less than 6 years of age), in whom truncal valve replacement was performed. This is an important finding as it suggests that younger children may benefit from truncal valve repair rather than a replacement with a smaller (non-adult sized) mechanical prosthesis which may require repeat replacement. Furthermore, if repair of the truncal valve is possible, this would avoid life-long anti-coagulation and the associated risks. In the long-term, patients had an excellent functional status following truncus arteriosus repair but had a high rate of reoperation due to the use of a conduit for reconstruction of the right ventricular outflow tract. Despite the high reoperation rate, patients have similar quality of life compared to age-matched Australian controls. This Doctor of Philosophy has redefined our understanding of the long-term outcomes of truncus arteriosus repair. The findings presented will impact clinical decision making, and I envision an improvement in the outcomes of these rare and complex patients.