Key result
Event-related signal averaging showed that sudden prolongation of F-QRS and decreased RMS 40-I immediately before PVCs were related to PVC appearance and persisted after PVCs in patients with VT.
Why the study?
Does event-related signal averaging of the QRS complex detect beat-to-beat changes associated with ventricular tachycardia in patients with premature ventricular contractions?
Observational (n=82)
Does event-related signal averaging of the QRS complex detect beat-to-beat changes associated with ventricular tachycardia in patients with premature ventricular contractions?
Event-related signal averaging reveals that transient beat-to-beat changes in high-frequency QRS components persist after premature ventricular contractions in patients with ventricular tachycardia, suggesting electrophysiologically favorable conditions for reentry.
May indicate reentry vulnerability in VT via QRS changes; leaves open clinical utility pending prospective validation.
In this study, we evaluated the relationship between beat-to-beat changes in high frequency components of the QRS complex and ventricular arrhythmias by using a newly developed event-related (ER) signal averaging technique. The study involved 82 patients with premature ventricular contractions (PVC), 56 of whom, including 16 with ventricular tachycardia (VT), were enrolled in Analysis I. In Analysis I, averaged sinus beats were classified into three patterns: 1) the sinus beat immediately before PVC (BEF); 2) that immediately after PVC (AFT); and 3) all sinus beats (ALL). Analysis II covered the remaining 26 patients, and involved five modes of event-related signal averaging, using: 1) the second beat preceding PVC (2-B); 2) the beat immediately preceding PVC (1-B); 3) the beat immediately after PVC (1-A); 4) the second beat after PVC (2-A); and 5) the beat isolated (ISO) from PVC. The filtered QRS duration (F-QRS) and the integral voltage of the terminal 40 msec (RMS 40-I) were measured using these averaging patterns. F-QRS in the VT group was longer than that in the non-VT group, but RMS 40-I was shorter. The F-QRS of BEF (1-B) was significantly longer than that of AFT (1-A). The transient difference in the F-QRS was observed in both VT and non-VT groups. This difference was almost eliminated at AFT (1-A) in the non-VT group, but was stable at AFT (1-A) in the VT group. Simultaneousely, RMS 40-I in BEF was significantly shorter than that in AFT. This transient decrease of RMS 40-I was observed in both VT and non-VT groups. Although RMS 40-I after this decrease showed a return almost to the control level at AFT in the non-VT group, it tended to remain even at AFT in the VT group. The sudden prolongation of F-QRS that occurred with the RMS 40-I decrease in BEF was related to the appearance of PVCs. We attributed the fact that these changes in F-QRS and RMS 40-I were observed even at AFT in the VT group to electrophysiologically preferable conditions for reentry.
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Kuroki et al. (2001) conducted an observational in Premature ventricular contractions (PVC) (n=82). Event-related (ER) signal averaging technique vs. Non-VT group and different beat patterns was evaluated on Filtered QRS duration (F-QRS) and integral voltage of the terminal 40 msec (RMS 40-I). Event-related signal averaging showed that sudden prolongation of F-QRS and decreased RMS 40-I immediately before PVCs were related to PVC appearance and persisted after PVCs in patients with VT.
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