Abstract P187: Does Pre-implantation QRS Morphology Influence the Outcomes After Cardiac Resynchronization Therapy?
Data about the role of pre-implantation QRS morphology in patients receiving cardiac resynchronization therapy (CRT) devices is limited. We hypothesized that pre-implantation QRS morphology influences the outcomes in CRT patients.
Methods: We retrospectively studied 99 patients (males 70, age 70±11 years) who had CRT implantation between 2003 and 2008. Pre-implantation QRS duration (QRSD) was 161±27ms. Patients were divided into 4 groups: group I, 51 patients with left bundle branch block (LBBB); group II, 13 patients with intra ventricular conduction delay (IVCD); group III, 27 patients with right ventricular paced rhythm (RVPR); and group IV, 8 patients with right bundle branch block (RBBB). All patients had echocardiograms before CRT and during follow up. A decrease of left ventricular (LV) end systolic volume ≥15% was defined as a positive response to CRT.
Results: During follow-up of 13±10 months, the LV ejection fraction by echocardiogram significantly increased from 22±7% to 27±12% (p=0.0001). 45% of our patient population (45/99) had positive response to CRT. There were 22 (43%) responders in group I, 5 (38%) in Group II, 14 (52%) in Group III and 4 (50%) in Group IV (p=0.83). QRS morphology (LBBB, IVCD, RVPR or RBBB) had no influence on CRT response by univariate regression (p=NS). During follow up of 17±9 months, 7 patients died. IVCD was related to mortality both by univariate (OR=6.2, p=0.03) and multivariate regression (OR=9.0, p=0.03). Survival, analyzed by Kaplan-Meier, in patients with IVCD was significantly lower compared to other groups (p=0.008). After CRT, QRSD in the non-IVCD patients improved significantly (161±26 to 154±29 ms, p=0.02) but not in patients with IVCD (141±28 to 145±30 ms, p=0.68).
Conclusion: IVCD, as compared to the other three QRS morphologies, predicted a worse outcome in CRT patients. Larger studies are needed to further evaluate this topic.