An additional marker of ventricular dyssynchrony

Patients suffering from heart failure with left bundle branch block (LBBB) can be effectively treated by resynchronization therapy (CRT). The ejection fraction, QRS duration (QRSd) and QRS morphology are the main selection criteria. Unfortunately, approximately one-third of CRT recipients are non-responders. Here we introduce an additional marker capable of distinguishing ventricular dyssynchrony more accurately. Methods: Ultra-high-frequency (UHF, sampling 25 kHz) 12-lead ECG, resting supine position, was measured. We analyzed 21 LBBB patients selected for CRT; the QRSd min/mean/max was 130/163/190 ms. Amplitude envelopes in the 500-1,000 Hz passband were computed and averaged with an R-wave trigger for each patient in the V1 and V6 leads. V1-V6 dyssynchrony (DYS) was computed as the time difference between UHF amplitude maximums in the V1 and V6 QRS complex region. Results: The DYS parameter min/mean/max was 1/68/115 ms. Patients with a small value of the DYS parameter, in spite of the fact that their QRS duration meets CRT criteria (> 120 ms), are not expected CRT responders. The DYS parameter indicates ventricular dyssynchrony and can potentially increase the percentage of CRT responders.