Background: Echocardiographic atrioventricular (AV) optimization after cardiac resynchronization therapy (CRT) is uncommon due to time constraints and the use of vendor-specific device algorithms. It remains unclear whether optimization of mitral inflow velocities can still be useful. We aimed to investigate post implantation left ventricular (LV) inflow patterns to determine the incidence of AV dyssynchrony from empirically set devices. Methods: This was a retrospective study of patients undergoing CRT using empiric device settings. Forty-eight patients with clinical, echocardiographic, and pacemaker follow-up were grouped by their post implantation LV filling pattern. Baseline characteristics and echocardiographic measurements were compared with post implantation findings at median 6.3 months (interquartile range [IQR], 3.9-17.0). Results: Twenty-four patients demonstrated AV dyssynchrony (Group 1) after CRT, and 24 patients did not (Group 2). Group 1 patients had less LV reverse remodeling compared to Group 2 patients (Delta LV end-diastolic volume: -3.6 mL vs -49.5 mL, P <.05; Delta LV end-systolic volume: -16.9 mL vs -53.5 mL, P <.05) and did not experience significant improvements in LV outflow tract velocity time integral, stroke volume, or LV ejection fraction. There were no differences in new-onset atrial fibrillation, heart failure readmissions, or mortality between groups. Conclusion: 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.