Automatic measurement of short-term variability of repolarization captures modulation by pacing on human electrograms.

BACKGROUND

Short-term variability of repolarization (STV) increases prior to ventricular arrhythmias in both humans and animal models, making it a promising tool for real-time arrhythmic risk monitoring.

OBJECTIVE

An automatic STV measurement algorithm was developed for intracardiac electrograms (EGMs) to enable integration into cardiac devices. This method previously demonstrated high accuracy in predicting life-threatening ventricular arrhythmias in animals. This study compared the performance of the automatic method to the gold standard on EGMs in humans.

METHODS

EGM signals were recorded in 14 patients with a dual-chamber implantable cardioverter-defibrillator during de novo implantation (n = 5) or replacement (n = 9) procedures. Recordings were obtained in sinus rhythm (SR), atrial pacing at 80 beats/min, and dual-chamber pacing at 80 beats/min. STV was determined on the EGM from the activation recovery interval with the automatic method (STV-ARI) and with fiducial segment averaging (STV-ARI), the gold standard. STV-ARI was compared with STV-ARI for all pacing modes.

RESULTS

STV-ARI and STV-ARI decreased from 0.90 ± 0.51 ms and 0.99 ± 0.39 ms in SR (53 ± 9 beats/min) to 0.60 ± 0.37 ms (and 0.68 ± 0.39 ms in atrial pacing at 80 beats/min, and to 0.32 ± 0.15 ms and 0.59 ± 0.24 ms in dual-chamber pacing at 80 beats/min, respectively (all .05 compared with SR). STV-ARI strongly correlated with STV-ARI (r = 0.80, .0001), with a small bias of 0.18 ms and limits of agreement between -0.35 and 0.70 ms.

CONCLUSION

The novel automatic STV measurement method accurately reflects pacing-induced changes, comparable to the gold standard. Future integration of this technique in implantable cardioverter-defibrillators could furnish continuous monitoring of arrhythmic risk and initiate preventive strategies.