Assessment of Right Ventricular Myocardial Fibrosis and Restrictive Physiology in Patients With Repaired Tetralogy of Fallot: A Comparison Between Cardiac Magnetic Resonance and Transthoracic Echocardiography

Right ventricular (RV) restrictive physiology is a condition caused by the chronic elevation of systolic pressure in the RV, which is typically found in patients with tetralogy of Fallot (ToF) who had undergone total surgical correction and can be diagnosed either via cardiac magnetic resonance imaging (CMR) or finding the RV end-diastolic forward flow (EDFF) via echocardiography. We aimed to assess the relationship between RV restrictive physiology with myocardial fibrosis and functional indices on CMR, along with exercise capacity and diastolic dysfunction indicators measured by transthoracic echocardiography (TTE).  

All patients with a history of the total correction of ToF at childhood who referred to our center for the evaluation of postoperative severe pulmonary regurgitation were included. All the patients were examined using electrocardiography, the exercise test, TTE, and late gadolinium enhancement (LGE) CMR.  

Among the study population, 17 (56.7%) patients were found to have RV EDFF on their echocardiograms, while 18 (60.0%) had RV restrictive physiology on their CMR. The 2 diagnostic modalities had a moderate significant agreement for the diagnosis of RV restrictive physiology (Kappa = 0.521, P= 0.004). There was a significant difference between the patients with or without RV restrictive physiology based on CMR findings regarding the QRS duration (P = 0.015), Sm (P = 0.045), and the RV end-diastolic volume index (P = 0.036).  

TTE may be a good alternative for the evaluation of RV restrictive physiology after the total correction of ToF. However, RV restrictive physiology measured by CMR and RV EDFF measured by echocardiography could not correlate with quantitative RV myocardial fibrosis measured by LGE CMR. (Iranian Heart Journal 2020; 21(3): 87-97)