Timing of the left ventricular electrogram and acute hemodynamic changes during implant of cardiac resynchronization therapy devices.

ABSTRACT

STUDY OBJECTIVE: To examine the relationship between timing of the left ventricular (LV) electrogram (EGM) and its acute hemodynamic effect on instantaneous change in LV pressure (LVdP/dt(MAX)). PATIENTS AND METHODS: In 30 patients (mean = age 67 +/- 7.9 years) who underwent implant of cardiac resynchronization therapy systems, the right ventricular (RV) lead was implanted at the RV apex (n = 23) or RV septum (n = 7). The LV lead was placed in a posterior (n = 14) or posterolateral (n = 16) coronary sinus tributary. QRS duration, interval from Q wave to intrinsic deflection of the LV EGM (Q-LV), and interval between intrinsic deflection of RV EGM and LV EGM (RV-LV interval) were measured. The measurements were correlated with the hemodynamic effects of optimized biventricular (BiV) stimulation, using the Pearson correlation coefficient. RESULTS: The mean LVdP/dt(MAX) at baseline was 734 +/- 180 mmHg/s, and increased to 905 +/- 165 mmHg/s during simultaneous BiV pacing, and to 933 +/- 172 mmHg/s after V-V interval optimization. The Pearson correlation coefficient R between QRS duration, the Q-LV interval, and the RV-LV interval at the respective LVdP/dt(MAX) was 0.291 (P = 0.66), 0.348 (P = 0.030), and 0.340 (P = 0.033). CONCLUSIONS: Similar significant correlations were observed between the acute hemodynamic effect of optimized BiV stimulation and the Q-LV and the RV-LV intervals. However, individual measurements showed an 80-ms cut-off for the Q-LV interval, beyond which the increase in LVdP/dt(MAX) was <10%.