Atrioventricular dyssynchrony from empiric device settings is common in cardiac resynchronization therapy and adversely impacts left ventricular morphology and function.

Our study suggests that up to 50% of patients with empiric device settings have AV dyssynchrony at 6 months despite atrioventricular delay optimization (AVO) algorithms. As AV dyssynchrony is common and has proven to be modifiable, a strategic approach to Doppler echocardiography-guided AVO after CRT is warranted, particularly in nonresponders where the LV filling pattern is fused or truncated.