Most patients with d-transposition of the great arteries who underwent arterial switch operation had preserved left ventricular function on cardiac magnetic resonance imaging, according to findings from a single-center retrospective study.
Researchers reviewed cardiac magnetic resonance imaging (CMR) studies performed from 2011 to 2019 in pediatric and adult patients with repaired d-transposition of the great arteries (d-TGA) following neonatal arterial switch operation (ASO). The final analysis included 52 CMR studies after exclusions for left ventricular outflow obstruction, inadequate imaging sequences, and repeat studies from the same patient.
The median age at CMR was 14.3 years, and 33% of patients were male — a notable cohort characteristic given the typical male predominance reported in d-TGA populations. Ten patients (19%) had a history of repaired ventricular septal defects. Among the 32 patients with available surgical timing data, the median age at ASO was 4 days.
Overall, left ventricular systolic function was preserved in most patients. Median left ventricular ejection fraction (LVEF) was 60%, and nine patients (17%) had reduced LVEF, defined as less than 55%. Five of those patients were pediatric patients and four were adults. No patients had severe systolic dysfunction.
Feature-tracking strain analysis was performed with dedicated CMR software by a single investigator. Among adult patients, 2D and 3D global left ventricular strain values were within published normal ranges. Median adult 2D global longitudinal strain was −18.1%, and median 3D global longitudinal strain was −11.5%.
The findings differed from those of a conference abstract by Schuwerk et al., which reported significantly impaired global longitudinal and circumferential strain in patients following ASO compared with healthy controls. The current investigators noted that their adult cohort did not demonstrate abnormal absolute strain values relative to published normative reference ranges.
Normative pediatric strain comparisons were unavailable, although median pediatric 2D and 3D global longitudinal strain values were −20.4% and −13.34%, respectively.
Neoaortic regurgitation was generally mild. Nineteen patients had no regurgitation, 27 had regurgitant fraction below 10%, and four had regurgitant fraction between 11% and 20%. One patient had severe regurgitation with regurgitant fraction of 39%.
Coronary anatomy was determinable in 47 studies, with usual coronary arrangement observed in 31 (66%). The next most common pattern was left circumflex artery arising from the right coronary artery.
Late gadolinium enhancement (LGE) was present in five patients (9.6%). Enhancement sites included the right ventricular insertion site in two patients, the left ventricular inferior septal wall in one patient, the right ventricular outflow tract anterior free wall in one patient, and the left ventricular basal anterolateral wall in one patient. The researchers noted that LGE may reflect myocardial scar tissue and fibrosis, which can represent an arrhythmia risk factor in this population.
The investigators also emphasized the growing importance of long-term surveillance as the earliest ASO cohorts age into adulthood and middle age, when acquired cardiovascular risk factors such as hypertension, diabetes, obesity, and smoking may interact with reimplanted coronary anatomy in ways that remain incompletely understood.
The study was limited by its retrospective, single-center design; small sample size; exclusion of some earlier CMR studies because of inadequate imaging sequences; lack of longitudinal follow-up; and absence of interobserver or intraobserver variability assessment. The sample size also precluded meaningful subgroup analysis.
“These results suggest that CMR assessment of the LV and neoaortic valve is reassuring in most teenage and young adult patients after neonatal-age ASO,” wrote lead study author Krittika Joshi, MD, of Arkansas Children’s Hospital, and colleagues. The researchers added that CMR may be particularly useful for detecting scar tissue via LGE in patients with concern for arrhythmia burden.
The researchers reported no external funding and no conflicts of interest.
Source: Annals of Pediatric Cardiology
