T-Wave Peak-to-End Changes Quantified by Time-Warping Predicts Ventricular Fibrillation in a Porcine Myocardial Infarction Model

Abstract

Background: The mathrm{T}-{pe}-interval time-warping-based morphology variation index, derived from a spatially transformed PCA lead, d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}}, has previously demonstrated utility in tracking repolarization changes induced by a 5-minute ischemia model in humans. The value of d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} as a predictor of ventricular fibrillation (VF) episodes is assessed in a 40-minutes porcine infarction model. Preocclusion and occlusion ECG recordings from 10 pigs who suffered a late VF episode and 16 who did not were analyzed. The d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} series was measured by comparing mathrm{T}-{pe} morphologies at different stages of the occlusion relative to a baseline. During baseline, d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} remained stationary with an intra-recording median [IQR] value of 1.60 [1.33] ms. During occlusion, d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} followed a well-marked gradual increasing trend, reaching a median of 14.58 [17.72] ms. d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} averages were significantly higher in the VF group than in the Non-VF group at five time intervals taken every 5 minutes after occlusion onset with median values of 12.5, 18.8, 26.8, 24.0, and 31.0, vs 6.3, 7.6, 8.0, 7.8, and 7.8, and also at three consecutive 5-minute intervals prior to VF 18.6, 25.0 and 28.8 vs 8.5, 7.2 and 6.0 ms, respectively. The mathrm{T}-{pe}{text{PCA}} interval was also significantly higher in the VF group at all analyzed time periods, but with a lower significance level. Pigs with maximum d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} ≥ 20.0 ms and mathrm{T}-{pe}{text{PCA}} ≥ 85.4 ms in the early 5-10 minutes interval after occlusion, had significantly higher risk for VF occurring with 90.0%/75.0% and 80.0%/69.0% sensitivity/ specificity, respectively. In conclusion, d{text{PCA}}-{w,{scriptscriptstyle mathrm{T}-{pe}}} is a stronger VF predictor than mathrm{T}-{pe}{text{PCA}} during ischemia in a porcine model.