In this work, we use a time-warping-based morphology variation index, dw, computed between the peak and the end of the T-wave, and assess its association with the occurrence of ventricular fibrillation (VF) episodes in ischemic conditions. ECG recordings from 26 pigs undergoing a 40-minute coronary occlusion were analyzed. The dw series was obtained by quantifying the morphological differences between the final part of the T wave at different stages of the occlusion and a reference T wave in the control recording. During control recordings, dw remained stationary with a median value along each recording of 1.76 ms, IQR of 1.80, while during artery occlusion followed a well-marked gradual increasing trend as ischemia progressed, with median of 15.47 ms, IQR of 18.53. At the 20-to-25 min period from occlusion onset (and during 5 min prior to VF episode) dw averages in the VF group was significantly higher than in the non-VF group with median values of 40.0 (and 34.4) vs 7.8 (and 7.7) ms, with p-values of 0.002 (and 0.001), respectively. In conclusion, dynamic increases of the dw index during ischaemia progression in pigs are associated with VF occurrence.