Pediatric Track Session
SCMR 22nd Annual Scientific Sessions
Adults with repaired tetralogy of Fallot (rTOF) are at risk of ventricular arrhythmia and sudden cardiac death (SCD). Myocardial scar is a substrate for re-entry ventricular tachycardia (VT). Inducibility of VT during invasive programmed VT stimulation predicts survival. The prognostic role of late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) remains uncertain.
Sixty-nine rTOF patients (43 male, age 38;28-52 years) undergoing clinically-indicated invasive programmed VT-stimulation had pre–procedure 3D LGE CMR using a whole-heart respiratory-navigated inversion-recovery sequence. Ventricular myocardial fibrosis was manually segmented and right ventricular (RV), left ventricular (LV) fibrosis and combined biventricular (BiV) fibrosis volumes were calculated. Fusion of the segmented fibrosis regions with 3D reconstructed heart chambers and vessels (from 3D balanced Steady-State Free-Precession; bSSFP), enabled measurement of the shortest distance between scar perimeters (anatomical isthmuses).
VT was induced in 31% (n=22) rTOF patients.
Univariate predictors of VT inducibility included increased RV LGE volume (HR 1.15; CI 1.06-1.25, P=0.001), increased BiV LGE volume (HR 1.1; CI 1.04-1.16, P=0.001), narrower width of anatomical isthmus 2 (distance between pulmonary valve and RVOT scar) HR 1.1; CI 1-1.2, P=0.05, higher age decile (HR 1.6; CI 1.1-2.3, P=0.01) and QRS duration greater than 180ms (HR 3.5; CI 1.2-10.7, P=0.02).
RV LGE volume was a good discriminator of VT inducibility with an area under the ROC curve of 0.81 (CI 0.7-0.9, P <0.001). RV LGE fibrosis volume <10.2cm3 was 100% sensitive for negative inducibility and RV fibrosis volume >36.0cm3 was 100% specific for inducible VT. In bivariate analysis, RV LGE volume independently predicted inducible VT (HR 1.18, CI;1.06-1.3, P=0.002) over the other univariate predictors.
CMR 3D LGE-defined fibrosis volume predicts VT inducibility independent of increased age or QRS duration≥180ms. For every 1cm3 increase in RV LGE there is a 15% increased risk of VT inducibility. 3D LGE could have a role for selection of patients for programmed VT stimulation including to identify patients in whom an invasive study could be avoided.