Key result
Long-term survivors of the arterial switch operation had elevated LV native T1 times (1042 vs 1011 ms, P<0.01) and altered contraction patterns compared to controls, despite normal EF.
Why the study?
Do long-term survivors of the arterial switch operation for transposition of the great arteries exhibit imaging markers of myocardial fibrosis and altered myocardial function compared to healthy controls?
Cross-Sectional (n=58)
Do long-term survivors of the arterial switch operation for transposition of the great arteries exhibit imaging markers of myocardial fibrosis and altered myocardial function compared to healthy controls?
Absolute Event Rate: 1042% vs 1011%
p-value: p=<0.01
Long-term survivors of the arterial switch operation exhibit elevated imaging markers of diffuse myocardial fibrosis and altered LV contraction patterns despite normal systolic function.
Normal EF may mask diffuse fibrosis in arterial switch survivors; leaves open prognostic value of T1 mapping.
Aims: The objective of this study was to quantify imaging markers of myocardial fibrosis and assess myocardial function in long-term transposition of the great arteries survivors after the arterial switch operation (ASO). Methods and results: Paediatric ASO patients were prospectively studied by cardiac magnetic resonance imaging, including first-pass myocardial perfusion, late gadolinium enhancement, and T1 relaxometry, as well as echocardiography for left ventricular (LV) systolic and diastolic function including strain analysis, with comparison to healthy controls. Thirty ASO patients (mean age 15.4 ± 2.9 years vs. 14.1 ± 2.6 years in 28 controls, P = 0.04) were included. Patients had normal LV ejection fraction (EF) (57 ± 5% vs. 59 ± 5%, P = 0.07), but end-diastolic and end-systolic volumes were increased (104 ± 20 mL/m2 vs. 89 ± 10 mL/m2, P < 0.01 and 46 ± 13 mL/m2 vs. 36 ± 7 mL/m2, P < 0.01, respectively). Longitudinal strain at two-, three-, and four-chamber levels of the LV were lower in ASO patients (-19.0 ± 2.6% vs. -20.9 ± 2.3%, P = 0.006, -17.7 ± 2.0% vs. -19.1 ± 2.4%, P = 0.02, and -18.9 ± 1.9% vs. -20.1 ± 1.7%, P = 0.01, respectively), while circumferential strain was higher at all short-axis levels (-24.6 ± 2.3% vs. -19.3 ± 1.6%, P < 0.001 at the mid-ventricular level). LV native T1 times were higher in ASO patients (1042 ± 27 ms vs. 1011 ± 27 ms, P < 0.01) and correlated with LV mass/volume ratio (R = 0.60, P < 0.001). Myocardial scarring or myocardial perfusion defects were not observed in our cohort. Conclusion: Children and adolescents after ASO have normal LV systolic function, in line with their overall good clinical health. At a myocardial level however, imaging markers of diffuse myocardial fibrosis are elevated, along with an altered LV contraction pattern. Whether these abnormalities will progress into future clinically significant dysfunction and whether they are harbingers of adverse outcomes remains to be studied.
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Grotenhuis et al. (2018) conducted a cross-sectional in Transposition of the great arteries (n=58). Arterial switch operation (ASO) vs. Healthy controls was evaluated on LV native T1 times (p=<0.01). Long-term survivors of the arterial switch operation had elevated LV native T1 times (1042 vs 1011 ms, P<0.01) and altered contraction patterns compared to controls, despite normal EF.
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