Detecting early structural and functional myocardial alterations in patients with repaired tetralogy of fallot: a prospective MRI study.

In patients with repaired tetralogy of Fallot (rTOF), right ventricular (RV) fibrosis has been associated with ventricular tachycardia, heart failure, and sudden cardiac death. Here, we aimed to identify links between diffuse myocardial fibrosis and regional mechanical dysfunction by cardiac magnetic resonance imaging (CMR) in rTOF. Clinical CMR was extended in 17 consecutive rTOF patients (median age 20 years, 4 females) to include biventricular native T1 (nT1) mapping as indicator of diffuse fibrosis, and tissue phase mapping (TPM) for quantification of biventricular segmental, directional systolic/diastolic myocardial velocities. Patients demonstrated smaller peak velocities than healthy volunteers in both ventricles (e.g. LV-base circumferential peak-systolic velocity: median [IQR] -0.9 [1.5] vs. -3.0 [1.2] cm/s, p < 0.001). RV peak velocities were reduced even in patients with normal RV ejection fraction (e.g. RV-mid long-axis peak-diastolic velocity: -3.3 [1.2] vs. -6.9 [1.8] cm/s, p = 0.001). Global LV nT1 was higher in patients versus controls (1029 [48] vs. 993 [28] ms, p = 0.013). Within the rTOF group, fibrosis in lateral LV correlated with shorter time-to-peak-velocity (TTP), whereas fibrosis in inferior RV correlated with longer TTP. Therefore, in rTOF TPM facilitates early diagnosis of impaired systolic and diastolic myocardial function while diffuse fibrosis has differential effects on RV and LV mechanics.