Introduction: There are several methods for programming the optimal AV delay (AVD) during cardiac resynchronization therapy (CRT). These include Doppler echocardiographic measurements of mitral inflow or aortic outflow velocities, an arbitrarily fixed AVD, and calculations based on intracardiac electrogram (EGM) intervals. The present study was designed to compare the acute effects of AVD programming methods during CRT.
Methods and results: We studied 28 patients at CRT implant with invasive measurements of LV dP/dt to determine the effect of AVD during atrial sensed (AS) and atrial paced (AP) modes. The optimal AVD, defined as that resulting in the maximal LV dP/dt, was then compared with that predicted by several noninvasive methods. CRT increased LV dP/dt 11% +/- 11% during AS (heart rate: 73 +/- 14 bpm) and 17% +/- 12% during AP (heart rate: 86 +/- 12 bpm) (P < 0.001 vs AS). There was an excellent correlation between the EGM method and the maximum achievable LV dP/dt (AS: R2 = 0.99, P < 0.0001, AP: R2 = 0.96, P < 0.0001) and this method performed better than other techniques.
Conclusions: An electrogram-based optimization method accurately predicts the optimal AVD among patients over a wide range of QRS intervals during CRT in both AS and AP modes. This simple technique may obviate the need for echocardiography for AVD programming.