Abstract
Purpose: Response to cardiac resynchronization therapy (CRT) is commonly defined as a reduction of LV end-systolic volume (ESV) >15% after 6 or 12 months of implantation. However, no data of patients showing later responses to CRT is available. We assessed clinical outcomes and subsequent change of QRS duration in patients showing responses to CRT after 12 months of implantation.
Methods: We retrospectively enrolled 41 patients with CRT implantation from February 2006 to April 2015. Patients without available echocardiography data after 12 months of CRT implantation were excluded. Eligible 29 patients were categorized by echocardiographic results. Responder was defined as a patient with 15% reduction in ESV or 10% increase in ejection fraction (EF) on any follow up echocardiogram. Response after 12 months was defined as late. QRS duration was measured before and after 1 day, 6 months, 12 months, 24 months of CRT implantation. The clinical outcome and the change in QRS duration were assessed.
Results: Total follow up period was 41.5 ± 29.1 months. Mean age was 66.97 ± 11.23 years and 13/29 (44.8%) were male. There were 17/29 (58.6%) early responders, 7/29 (24.1%) late responders and 5/29 (17.2%) non responders. Proportion of ICMP was 3/17 (17.6%) in the early responders, 2/7 (28.6%) in the late responders and 1/5 (20%) in the non responders (p = 0.834). In the late responder group, QRS duration was immediately decreased after CRT implantation and subsequently decreased after 6 months whereas in the non responder group, QRS duration immediately decreased after CRT implantation and then increased to the higher value than the baseline after 6 months (figure 1). The number of hospitalizations due to cardiac disease was 0.19/year in the early responder group, 0.51/year in the late responder group and 0.91/year in the non responder group (p = 0.043).
Conflict of interest: none
