Metabolic heterogeneous zone assessed by ¹⁸FDG-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 ¹⁸Fluorodeoxyglucose (¹⁸FDG) positron emission tomography (PET) viability studies in ventricular tachycardia (VT) patients. Methods: PET studies utilizing ⁸²Rubidium (⁸²Rb) tracer for perfusion and ¹⁸FDG tracer for viability were analyzed using PMOD (PMOD Technologies) and further analyzed using 684-segment plots. ¹⁸FDG uptake was normalized to the area with maximal perfusion on the rest ⁸²Rb study. Metabolic scar, HZ, and healthy segments were defined with perfusion-normalized ¹⁸FDG uptake between 0%–50%, 50%–70%, and >70%, respectively. Results: Thirty-four VT patients (age, 63 ± 12 years) were evaluated with ¹⁸FDG-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 cm². HZ size was significantly larger in the deceased group than the alive group (35.2 cm² vs. 18.1 cm², p =.01). Deaths were significantly higher in HZ ≥ 21 cm² group than HZ < 21 cm² group (58.8% vs. 11.8%, p =.005). Survival analysis showed significantly higher mortality in the HZ ≥ 21 cm² group than the HZ < 21 cm² 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.