The Role of Systemic Atrial Function in Patients with Transposition of the Great Arteries

Objectives: In patients with transposition of the great arteries (TGA), the function of the systemic atrium (SA) and its interaction with the systemic ventricle (SV) after arterial switch operation (ASO) are not well understood. Therefore, we aimed to investigate atrial function and atrial-ventricular coupling in TGA after ASO, using cardiac magnetic resonance (CMR).

Methods: In this prospective single center analysis, patients with TGA status post-ASO and controls without known cardiovascular disease were studied with 3 Tesla cine CMR analysis of SA and SV function. In TGA patients, extracellular volume fraction (ECV) was assessed by T1 mapping and global longitudinal strain (GLS) by feature tracking.

Result: In the current study, 81 TGA (median, 16.3 [IQR: 10.5, 21.2] years, 32% female) and 30 control patients (11.9 [8.7, 22.5] years, 63% female) were included. SA maximum volume index (38 [30, 44] vs. 42 [38, 52] mL/m², p = 0.002), total atrial (17 [14, 21] vs. 24 [21, 29] mL/m², p < 0.001), and conduit emptying volume (10 [8.1, 14] vs.18 [15, 21] mL/m², p < 0.001) were lower in patients with TGA as compared with controls. SA reservoir (47 [42, 51] vs. 57 [51, 60]%, p < 0.001) and conduit function (28 [23, 34] vs. 43 [35, 46]%, p < 0.001) where lower as compared with controls. SA active/conduit (0.60 [0.41, 0.90] vs. 0.37 [0.28, 0.44], p < 0.001) and active/total ratio (0.38 [0.29, 0.47] vs. 0.27 [0.22, 0.30], p < 0.001) were higher among TGA patients indicating restricted passive filling of the SV. In TGA patients the median ECV was 28.3% (25.8, 33.9) and the median GLS –24.2% (28.6, –20.4). SA reservoir (r = –0.470, p < 0.001), conduit (r = –0.270, p = 0.022) and contractile function (r = –0.257, p = 0.030) correlated negatively with SV GLS, implying that impaired SA was associated with reduced SV function in TGA patients. ECV correlated positively with the SA active/conduit ratio (r = 0.418, p = 0.002) and the active/total ratio (r = 0.339, p = 0.013) but not with GLS (p = 0.637).

Conclusion: A reduced SA function was associated with deteriorated SV function and increased myocardial fibrosis in the SV. These findings suggest a pathophysiological vicious cycle with poor atrial function that begets ventricular fibrosis and reduced myocardial GLS, both of which further impact atrial function.

Publication History

Article published online:
21 February 2021