CMR feature tracking left ventricular strain-rate predicts ventricular tachyarrhythmia, but not deterioration of ventricular function in patients with repaired tetralogy of Fallot

Background: Myocardial strain has been shown to predict outcome in various cardiovascular diseases, including congenital heart diseases. The aim of this study was to evaluate the predictive value of cardiac magnetic resonance (CMR) feature-tracking derived strain parameters in repaired tetralogy of Fallot (rTOF) patients for developing ventricular tachycardia (VT) and deterioration of ventricular function. Methods: Patients with rTOF who underwent CMR investigation were included. Strain and strain-rate of both ventricles were assessed using CMR feature tracking. The primary outcome was a composite of the occurrence of sustained VT or non-sustained VT requiring invasive therapy. The secondary outcome was analyzed in patients that underwent a second CMR after 1.5 to 3.5 years. Deterioration was defined as reduction (≥10%) in right ventricular (RV) ejection fraction, reduction (≥10%) in left ventricular (LV) ejection fraction or increase (≥30 mL/m2) in indexed RV end-diastolic volume compared to baseline. Results: 172 patients (median age 24.3 years, 54 patients <18 years) were included. Throughout a median follow-up of 7.4 years, 9 patients (4.5%) experienced the primary endpoint of VT. Multivariate Cox-regression analysis showed that LV systolic circumferential strain-rate was independently predictive of primary outcome (p = 0.023). 70 patients underwent a serial CMR, of whom 14 patients (20%) showed ventricular deterioration. Logistic regression showed no predictive value of strain and strain-rate parameters. Conclusions: In patients with rTOF, LV systolic circumferential strain-rate is an independent predictor for the development of VT. Ventricular strain parameters did not predict deterioration of ventricular function in the studied population.