Metabolic heterogeneous zone assessed by FDG-PET is predictive of postablation mortality in patients with ventricular tachycardia.

Purpose: We sought to study the predictive value of the metabolic heterogeneous zone (HZ) as determined by Fluorodeoxyglucose ( FDG) positron emission tomography (PET) viability studies in ventricular tachycardia (VT) patients.

Methods: PET studies utilizing Rubidium ( Rb) tracer for perfusion and FDG tracer for viability were analyzed using PMOD (PMOD Technologies) and further analyzed using 684-segment plots. FDG uptake was normalized to the area with maximal perfusion on the rest Rb study. Metabolic scar, HZ, and healthy segments were defined with perfusion-normalized FDG uptake between 0%-50%, 50%-70%, and >70%, respectively.

Results: Thirty-four VT patients (age, 63 ± 12 years) were evaluated with FDG-PET viability study. Most (n = 31) patients underwent VT ablation. Patients were categorized to HZ < median versus HZ ≥ median based on a median HZ area size of 21.0 cm . HZ size was significantly larger in the deceased group than the alive group (35.2 cm vs. 18.1 cm , p = .01). Deaths were significantly higher in HZ ≥ 21 cm group than HZ < 21 cm group (58.8% vs. 11.8%, p = .005). Survival analysis showed significantly higher mortality in the HZ ≥ 21 cm group than the HZ < 21 cm group (HR = 4.1, 95% CI: 1.3-12.6, p = .016). In a multivariable analysis, HZ was found to be an independent predictor for all-cause mortality (HR = 1.07, 95% CI: 1.02-1.12, p = .01) CONCLUSIONS: Increased HZ size of myocardium was associated with increased mortality. Metabolic HZ quantification may be of value in risk stratification and management of ischemic and nonischemic patients with VT.