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Background: Studies have shown that echocardiographic (ECHO) optimization of atrioventricular (AV) and interventricular (VV) delays in cardiac resyncronization therapy (CRT) patients results in improvement of cardiac output by reducing left ventricular (LV) dyssynchrony. Intracardiac electrogram method (IEGM) is a novel technique based on the analysis of atrial intrinsic depolarization and interventricular conduction delay with yet undetermined clinical value.The aim of this study was to determine the efficacy of the IEGM compared to conventional ECHO-guided CRT optimization.Methods: 8 patients previously implanted with Medtronic CRT (3F/5M, 62.5±10.5 yrs) underwent IEGM-based delay optimization with optimal AV and VV delays obtained. Subsequently, MR dp/dt and LVOT VTI as echocardiographic markers of resynchronization effectiveness were measured. ECHO-guided optimization of the AV and VV dyssynchrony followed using PW Doppler of the mitral inflow and LV/RV outflow tract to measure interventricular mechanical delay, respectively. Pearson correlation analysis was used to evaluate findings.Results: A strong correlation between ECHO and IEGM-guided measurements was found, as follows: LVOT VTI (cc=0.979, p=0.896), dp/dt (cc =0.993 p=0.977), the final AV (cc=0.948, p=0.967) and VV delay (cc=0.980, p=0,787). However, the statistical significance was not achieved due to small studied sample.Conclusion: The IEGM proved to be as effective as the standard ECHO CRT optimization with the advantage of being less-time consuming. Due to present lack of scientific evidence further studies are required.