Transient and rapid QRS widening associated with J - wave pattern predicts impending ventricular fibrillation in experimental myocardial infarction

Background: Certain types of the early repolarization (ER) phenomenon, previously considered to be benign, have been reported to be associated with ventricular fibrillation (VF), both in population-based studies and in the myocardial infarction (MI) settings. Objective: Our aim was to analyse whether QRS widening and appearance of Jwave-pattern in experimental MI settings is predictive of VF. Methods: MI was induced in 32 pigs by 40-min inflation of an angioplasty balloon in the left descending artery (LAD) and ECG was continuously recorded. Multilead QRS boundaries were computed, and QRS duration was calculated on a beat-to-beat basis during the occlusion period for each pig. Association between QRS-widening and subsequent VF was studied using ROC-curve analysis. ECGs at maximum QRSduration were reviewed for the presence of J-wave pattern. Results: Sixteen animals had VF episodes during occlusion period. Two peaks of QRS widening were found in all animals: the first peak immediately on LAD occlusion, and the second peak 19.1±4.0 min later. The magnitude of changes in the QRS width over time had significant interindividual differences. QRS-widening ≥28 ms during a 3-min time window was observed in 14 animals and predicted impending VF (Se=80%, Sp=73%, PPV=57%, NPV=89%, p=0.008). In 10 of the 14 pigs, Jwave pattern appeared at maximal QRS duration. Appearance of J-wave-pattern predicted VF with Se=80%, Sp=68%, PPV=53%, NPV=88% p=0.02. Conclusions: Transient QRS widening, commonly associated with J-wave pattern, appears to predict impending VF in acute ischemia settings and motivates further clinical studies for monitoring immediate risk of VF in MI.