Abstract 422: Characteristics and Response to Cardiac Resynchronization Therapy in Heart Failure Patients With Left Bundle-Brunch Block and Atypical Dyssynchrony
Background: Heart failure patients with left bundle branch block typically have early septal followed by late posterolateral mechanical activation. However, an atypical pattern of late septal motion may occur, and its relationship to patient characteristics and response to resynchronization therapy (CRT) is unclear.
Methods: We studied 275 consecutive CRT patients (57% ischemic disease) with ejection fraction (EF) 24±7% (all ≤ 35%), and QRS 159±27ms (all ≥ 120ms). Longitudinal dyssynchrony was assessed by tissue Doppler (TDI) velocity as maximum opposing wall delay (3 apical views), and radial dyssynchrony by speckle tracking radial strain as anteroseptal to posterior wall delay (short axis views). Follow-up 7±5 mo. after CRT was available on 149. Response was defined as a ≥ 15% decrease in end-systolic volume.
Results: An atypical late septal dyssynchrony pattern was observed by longitudinal TDI in 63/275 (23%) by radial strain in 16/275 (6%) and by both in only 5/275 (2%). Age, gender, QRS width and EF were similar with typical and atypical dyssynchrony patterns overall. Response to CRT was similar with atypical and typical TDI longitudinal dyssynchrony (59% vs. 63%). However, patients with atypical radial dyssynchrony were more likely to have ischemic disease (81% vs. 55%, p<0.05) and a significantly lower response to CRT (20% vs. 65%, p<0.05).
Conclusions: In patients with wide QRS referred for CRT, atypical septal-late dyssynchrony is uncommon. When present however, patients with an atypical radial dyssynchrony pattern have a significantly lower response to CRT than those with typical dyssynchrony and these observations may play a role in patient management.