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

Objective assessment of the effect of Cardiac Resynchronization Therapy (CRT) still represents a very difficult clinical task. The ultra-high-frequency electrocardiographic (ECG) dyssynchrony (e-DYS) represents a simple ECG derived method that provides information about the ventricular electrical depolarization and thus could become helpful in CRT. The 12-lead ECG (sampling 5kHz/24bits) and echocardiography were obtained in 42 consecutive CRT patients. The e-DYS and standard QRS duration (QRSd) were automatically assessed before, just after, and 6 months after the CRT during CRT Off and CRT On. In 30 CRT responders determined by echocardiography, the e-DYS parameter was significantly lower after 6 months during CRT Off compared to state prior CRT (-9±19ms, p<0.05), while there was no significant e-DYS change during CRT On within 6 months (-1±11ms, NS). A clear shortage of e-DYS was observed just after CRT On (-46±23ms, p<10e-
¹⁰
), and 6 months after CRT On (-46±21ms, p<10e
^-10
) compared to state before CRT. No significant changes of the e-DYS parameter were found in 12 CRT non-responders. The QRSd didn’t show any significance in all observed changes. The e-DYS parameter seems to be a superior parameter to simply and quickly assess an immediate as well as the long-term effect in CRT.