Background: Adults with repaired tetralogy of Fallot die prematurely from ventricular tachycardia (VT) and sudden cardiac death. Inducible VT predicts mortality. Ventricular scar, the key substrate for VT, can be noninvasively defined with late gadolinium enhancement (LGE) cardiovascular magnetic resonance but whether this relates to inducible VT is unknown.
Methods: Sixty-nine consecutive repaired tetralogy of Fallot patients (43 male, mean 40±15 years) clinically scheduled for invasive programmed VT-stimulation were prospectively recruited for prior 3-dimensional LGE cardiovascular magnetic resonance. Ventricular LGE was segmented and merged with reconstructed cardiac chambers and LGE volume measured.
Results: VT was induced in 22 (31%) patients. Univariable predictors of inducible VT included increased RV LGE (odds ratio [OR], 1.15; P=0.001 per cm3), increased nonapical vent LV LGE (OR, 1.09; P=0.008 per cm3), older age (OR, 1.6; P=0.01 per decile), QRS duration ≥180 ms (OR, 3.5; P=0.02), history of nonsustained VT (OR, 3.5; P=0.02), and previous clinical sustained VT (OR, 12.8; P=0.003); only prior sustained VT (OR, 8.02; P=0.02) remained independent in bivariable analyses after controlling for RV LGE volume (OR, 1.14; P=0.003). An RV LGE volume of 25 cm3 had 72% sensitivity and 81% specificity for predicting inducible VT (area under the curve, 0.81; P<0.001). At the extreme cutoffs for ruling-out and ruling-in inducible VT, RV LGE >10 cm3 was 100% sensitive and >36 cm3 was 100% specific for predicting inducible VT.
Conclusions: Three-dimensional LGE cardiovascular magnetic resonance-defined scar burden is independently associated with inducible VT and may help refine patient selection for programmed VT-stimulation when applied to an at least intermediate clinical risk cohort.
Keywords: gadolinium; magnetic resonance imaging; myocardium; tetralogy of Fallot; ventricular tachycardia.