Abstract 2918: The Role of Pacemaker Optimization in CRT Non-Responders
Background: Approximately 30% of patients receiving cardiac resynchronization therapy (CRT) do not improve. One potential cause of non-response to CRT is that pacemaker parameters such as lower rate limit, atrio-ventricular (A-V) delay, or ventricular pacing lead configuration or activation sequence are not optimal.
Methods: We retrospectively analyzed 50 consecutive patients referred for pacemaker optimization (PMO) because of clinical incomplete- (52%) or non-response (48%) to CRT. Patients underwent a sequential echocardiography (ECHO)- tissue Doppler imaging (TDI)-guided PMO study to determine the optimal lower rate, A-V delay, and ventricular lead pacing configuration/timing.
Results: Time between CRT and PMO study was 13 ± 11 months. Age was 69.6 ± 11.1 years with 72% male patients. Two thirds of patients had ischemic cardiomyopathy. In 34 of 50 patients (68%) a change in pacemaker settings was made because an objective improvement was observed in ECHO/TDI findings. Of those patients, one or more of the following parameters were modified: decrease in lower rate limit (34%), change in A-V delay (60%), change in right ventricle (RV) to left ventricle (LV) timing (17%), discontinuation of RV lead pacing (23%), and discontinuation of CRT (3%). Fifteen patients (43%) had two or more of the above pacemaker changes. Comparison of baseline ECHO/TDI to PMO parameters in all 50 patients showed significant improvements in systolic function (TDI measured global systolic contraction score, p < 0.0001), diastolic function (diastolic filling period, p < 0.01, diastolic flow-velocity integral, p < 0.05), and dyssynchrony (TDI measured standard deviation of time to peak displacement, p < 0.05, number of walls with delayed onset of activation, p < 0.05).
Conclusion: We conclude that in approximately 2/3 of CRT non-responders, ECHO/TDI-guided PMO can be used to objectively improve cardiac systolic function, diastolic function, and/or LV mechanical dyssynchrony. Clinical effects of this approach remain to be determined. PMO is a reasonable and practical strategy for treatment of patients not responsive to CRT.