Automatic measurement of Short-Term Variability of repolarization to indicate ventricular arrhythmias in a porcine model of cardiac ischemia

Abstract Aims An automated method for determination of short-term variability of repolarization (STV) on intracardiac electrograms (STV-ARIauto) has previously been developed for arrhythmic risk monitoring by cardiac implantable devices, and has proved effective in predicting ventricular arrhythmias (VA) and guiding preventive high-rate pacing (HRP) in a canine model. Current study aimed to assess (1) STV-ARIauto in relation to VA occurrence and secondarily (2a) to confirm the predictive capacity of STV from the QT-interval and (2b) explore the effect of HRP on arrhythmic outcomes in a porcine model of acute myocardial infarction (MI). Methods and results MI was induced in 15 pigs. In 7/15 pigs STV-QT was assessed at baseline, occlusion, one minute before VA and just before VA. 8/15 pigs were additionally monitored with an electrogram catheter in the right ventricle, underwent echocardiography at baseline and reperfusion, and were randomized to paced or control group. Paced group received atrial pacing at 20 beats/minute faster than sinus rhythm one minute after occlusion. STV increased prior to VA in both STV modalities. The percentage change in STV from baseline to successive timepoints correlated well between STV-QT and STV-ARIauto. HRP did not improve arrhythmic outcomes and was accompanied by a stronger decrease in ejection fraction. Conclusion STV-ARIauto values increase before VA onset, alike STV-QT in a porcine model of MI, indicating imminent arrhythmias. This highlights the potential of automatic monitoring of arrhythmic risk by cardiac devices through STV-ARIauto and subsequently initiate preventive strategies. Continuous HRP during onset of acute MI did not improve arrhythmic outcomes.