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D-PO01-244 - Improvement In Mechanical Synchrony In Patients Receiving Corrective His Bundle Pacing: A Sub-analysis Of The His-sync Pilot (ID 981)


Background: Although His bundle pacing for cardiac resynchronization (His-CRT) has been shown to be associated with electrical resynchronization and left ventricular ejection fraction (LVEF) improvement, its impact on left ventricular synchrony remains unknown.
Objective: To utilize echocardiographic strain-imaging to assess determinants of mechanical synchrony after His-CRT.
Methods: The His-SYNC Pilot was a multicenter randomized trial of His versus biventricular CRT. For this analysis, on-treatment His-CRT were analyzed for myocardial strain using speckled doppler tracking (QLab, Phillips, Amsterdam). Peak systolic longitudinal and time to peak longitudinal strain were records using a 16-segment model; standard deviation of times to peak strain was calculated as a quantitative measure of mechanical dispersion (MD) as demonstrated in Figure 1 and correlated with improvement in left ventricular ejection fraction (LVEF).
Results: Average age was 63 years, 53% male, 173±18 ms QRS baseline QRS. His-CRT achieved significant QRS narrowing (173 ± 18 ms to 125 ± 21 ms, p<0.001) and was also associated with significant reduction in mechanical dispersion from baseline to 6 month follow up (251 ± 69 ms to 102 ± 43 ms, p <0.001) (see Figure). Greater mechanical dyssynchrony at baseline was correlated with LVEF improvement by 5% (rho = 0.23).
Conclusion: His-CRT is associated with significantly improved mechanical dispersion, with greater baseline dispersion correlated with greater likelihood of LVEF improvement.