Left ventricular diastolic filling prior to cardiac resynchronization therapy: Implications for atrioventricular delay programming

Background: The programmed atrioventricular delay (AVD) is an important determinant of the re-sponse in left ventricular (LV) systolic performance during cardiac resynchronization therapy (CRT). It is not well established if the optimal AVD for CRT may be influenced by the LV diastolic filling pattern. Methods: Thirty patients were studied pre- and post-CRT at programmed AVD of 60-160 ms. Doppler measurements included the aortic and mitral velocity time integral (VTI), mitral early (E) and late diastolic filling (A) wave velocities, E- and A-wave VTI, and diastolic filling time (DFT). The optimal AVD for each of the Doppler variables was defined by the maximal improvement compared to pre-CRT. Patients were grouped by the pre-CRT mitral inflow pattern as impaired relaxation (IR, mitral E/A ≤1, n = 15) or pseudonormalized/restrictive filling (PNF/RF, mitral E/A >1, n = 15). Results: The percentage of improvement in aortic VTI was greater in the PNF/RF group (P= 0.03). Mitral E-wave velocity decreased in the PNF/RF group (P < 0.001), E-wave VTI increased in both groups (P< 0.05) and A-wave VTI increased in the PNF/RF group. DFT increased in both groups. The optimal AVD that maximized aortic VTI was longer than the AVD that improved DFT. Conclusions: The effects of various programmed AVD during CRT on the response in LV stroke volume and diastolic filling are influenced by the pre-CRT LV filling characteristics. AVD optimization based on maximizing DFT is shorter compared to the aortic VTI method. (PACE 2008; 31:838-844).