The Ultra-High-Frequency QRS Dyssynchrony in the Assessment of Cardiac Resynchronization Therapy Effect

Pavel Leinveber1, Josef Halamek2, Pavel Jurak3, Magdalena Matejkova4, Radovan Smisek5, Filip Plesinger3, Jolana Lipoldova6, Miroslav Novak6
1International Clinical Research Center, St. Anne’s University Hospital, Brno, Czech Republic, 2Institute of Scientific Instruments, CAS, CZ, 3Institute of Scientific Instruments of the CAS, 4International Clinical Research Center, St. Anne's University Hospital, Brno, Czech Republic, 5Brno University of Technology, 6International Clinical Research Center, 1st Cardio-angiology department, St. Anne’s University Hospital, Brno


Background Objective assessment of the effect of Cardiac Resynchronization Therapy (CRT) is a very difficult clinical task that still has not been fully clarified. The ultra-high-frequency QRS dyssynchrony (DYS) represents a simple ECG derived method that provides information about the ventricular electrical depolarization and thus could become helpful in CRT.

Method The 12-lead ECG (sampling 5kHz/24bits) was measured in 42 consecutive CRT patients. The precordial V1-V6 QRS envelopes were calculated through various frequency ranges from 150 to 1000Hz. The DYS was measured as a difference between soonest and latest activation in V leads. The standard QRS duration (QRSd) was also automatically assessed. All the parameters were assessed before, just after, and 6 months after the CRT during CRT-OFF and CRT-ON. Patients with a relative decrease of 10% and more in the end-systolic volume of the left ventricle were considered CRT responders.

Results In 30 CRT responders, the DYS parameter was significantly lower after 6 months during CRT-OFF compared to state prior CRT (-9±19ms, p<0.05), while interestingly there was no significant DYS change during CRT-ON within 6 months (-1±11ms, NS). On the other hand, there was a clear shortage of DYS just after CRT-ON (-46±23ms, p<0.000001), and 6 months after CRT-ON (-46±21ms, p<0.000001) compared to state before CRT. In 12 CRT non-responders, there were no significant changes in DYS parameter. The QRSd didn’t show any significances in changes before, just after, and 6 months after CRT during CRT-ON and OFF in both CRT groups.

Conclusion The ultra-high-frequency QRS dyssynchrony parameter accurately describes the ventricular conduction pattern and seems to be a superior parameter to simply and quickly assess an immediate as well as long-term (reverse electrical remodeling) effect in CRT. The QRS duration as a descriptor of the ventricular conduction changes induced by CRT does not provide sufficiently valuable information.