Exercise Capacity in Patients Who Underwent Arterial Switch Operation: Does the Coronary Anatomy Matter?

Background: Variant coronary anatomy (VarCA) is frequent in d-Transposition of the great arteries (d-TGA) and increases the complexity of neonatal arterial switch operation (ASO) and adversely impacts short term outcomes. However, there is paucity of correlative data with respect to exercise capacity and its longitudinal changes.

Methods: This IRB-approved retrospective study included patients with d-TGA who underwent an ASO and had at least one cardiopulmonary exercise test (CPET) between 2005 and 2020. Patients with other congenital heart diseases, pacemaker, defibrillators, severe pulmonary stenosis, and those with inadequate data were excluded. Demographic data, including gender, height, weight, and coronary artery pattern was collected. Usual coronary anatomy was defined as the left main coronary artery and its branches arising from sinus 1 and the right coronary artery (RCA) arising from sinus 2 (facing sinuses). All other coronary artery origin patterns were considered variants (VarCA). Data regarding the treadmill CPET was also collected. The predicted oxygen consumption (%VO2) < 85% was regarded as abnormal. The parameters of CPET were compared between the patients with usual anatomy and VarCA. Analysis was also performed to assess the longitudinal changes and exercise parameters between the first and the last CPET were compared in each group (usual anatomy vs. VarCA).

Results: A total of 44 patients (68.2% male, median age at first CPET of 12.1 years) with either usual coronary anatomy (n=27, 61%) or VarCA (n=17, 39%) met inclusion criteria. The two groups were similar in demographics. There was no significant difference in %VO2 at initial CPET (104 vs. 100%, p = 0.531). A reduction in %VO2 ( <85%) was uncommon (n=2, 7.4% vs. n=4; 23.5%; p=ns). Longitudinal CPET data was available for 25 patients and there was no significant decline in %VO2 within the two groups: i) usual coronary anatomy (n=15, median follow-up 4.8 years, %VO2 111 vs. 108%; p = 0.306) and ii) VarCA (n=10, median follow-up 6.6 years, %VO2 106 vs. 92%; p = 0.441).

Conclusion: There was no demonstrable effect of coronary anatomy pattern on exercise capacity during intermediate follow-up in patients with d-TGA who underwent neonatal ASO. They uniformly exhibited good exercise capacity without any longitudinal decline during follow-up.