Role of prenatal cardiovascular magnetic resonance imaging in determining pregnancy risk in repaired Tetralogy of Fallot patients
Authors: Hon N W L , Wu M Z , Yu S Y , Wong P F , Tse Y K , Li H L , Tsui L H , Yu S Y , Yiu K H 
Published: February 2022

Funding Acknowledgements

Type of funding sources: None.

Addressing pregnancy risks poses as a new challenge among women with repaired tetralogy of Fallot (TOF). The high-output state of pregnancy may predispose women to late complications of repaired TOF. However, guidelines regarding antenatal and or perinatal cardiovascular assessment has not been outlined. Noninvasive modalities such as cardiac magnetic resonance imaging (CMR) that do not require the utilization of ionizing radiation are feasible methods of assessment. Risk stratification of baseline CMR parameters has been sparsely investigated among repaired TOF cohorts. This study aims to identify baseline CMR parameters that may predict adverse outcomes of pregnancy among women with repaired TOF.

Sixty-five successful pregnancies were recorded from a cohort of 105 pregnant episodes. Patients with CMR studies performed within 5 years prior to delivery events were included. Adverse clinical outcomes of interest included arrhythmia, heart failure admissions, gestational hypertension, pre-eclampsia toxemia and all-cause mortality. Baseline CMR parameters regarding ventricular mechanics such as left and right ventricular end-diastolic and end-systolic volumes, left and right ventricular ejection fractions and pulmonary regurgitant fraction were measured, and their association with adverse clinical outcomes were evaluated using an independent-samples t-test.

Within all 65 successful pregnancies, 26 baseline CMR images were obtained and included in this study. The mean maternal age was 29.7 ± 6.7 years old with a mean birth weight of 2.91 ± 0.49 kg at a mean gestational age of 38.4 ± 2.0 weeks. There was a total of 12 patients with adverse clinical outcome: 5 patients with heart failure hospitalizations, 4 patients with gestational hypertension, 4 patients with arrhythmia and 2 patients with pre-eclampsia toxemia.

Assessment of baseline CMR parameters of ventricular mechanics revealed that increased left ventricular end-diastolic volumes (LVEDV) (144.7mL/m2 ± 4.9; P = 0.011), left ventricular end-systolic volumes (LVESV) (65.1mL/m2 ± 9.4; P = 0.004), right ventricular end-diastolic volumes (RVEDV) (235.2 ± 29.0; P = 0.021) and right ventricular end-systolic volumes (RVESV) (122.2mL/m2 ± 38.1; P = 0.033) were associated with an increased incidence of arrhythmia during pregnancy. Nonetheless, there was no significant association between baseline ventricular mechanics with heart failure, gestational hypertension, and pre-eclampsia toxemia. 

Baseline assessment of cardiac magnetic resonance imaging among pregnant TOF women revealed that larger left and right ventricular volumes were associated with arrythmia development during pregnancy. Further studies with larger cohort sizes evaluating the role of antenatal and perinatal cardiovascular imaging assessment using CMR in predicting the risks of cardiovascular complications during pregnancy are warranted.