Identification of Typical Left Bundle Branch Block Contraction by Strain Echocardiography Is Additive to Electrocardiography in Prediction of Long-Term Outcome after Cardiac Resynchronization Therapy

Niels Risum, Bhupendar Tayal, Thomas F. Hansen, Niels E. Bruun, Magnus T. Jensen, Trine K. Lauridsen, Samir Saba, Joseph Kisslo, John Gorcsan, Peter Sogaard

Research output: Contribution to journalArticlepeer-review

Abstract

Background Current guidelines suggest that patients with left bundle branch block (LBBB) be treated with cardiac resynchronization therapy (CRT); however, one-third do not have a significant activation delay, which can result in nonresponse. By identifying characteristic opposing wall contraction, 2-dimensional strain echocardiography (2DSE) may detect true LBBB activation. Objectives This study sought to investigate whether the absence of a typical LBBB mechanical activation pattern by 2DSE was associated with unfavorable long-term outcome and if this is additive to electrocardiographic (ECG) morphology and duration. Methods From 2 centers, 208 CRT candidates (New York Heart Association classes II to IV, ejection fraction ≤35%, QRS duration ≥120 ms) with LBBB by ECG were prospectively included. Before CRT implantation, longitudinal strain in the apical 4-chamber view determined whether typical LBBB contraction was present. The pre-defined outcome was freedom from death, left ventricular assist device, or heart transplantation over 4 years. Results Two-thirds of patients (63%) had a typical LBBB contraction pattern. During 4 years, 48 patients (23%) reached the primary endpoint. Absence of a typical LBBB contraction was independently associated with increased risk of adverse outcome after adjustment for ischemic heart disease and QRS width (hazard ratio [HR]: 3.1; 95% CI: 1.64 to 5.88; p < 0.005). Adding pattern assessment to a risk prediction model including QRS duration and ischemic heart disease significantly improved the net reclassification index to 0.14 (p = 0.04) and improved the C-statistics (0.63 [95% CI: 0.54 to 0.72] vs. 0.71 [95% CI: 0.63 to 0.80]; p = 0.02). Use of strict LBBB ECG criteria was not independently associated with outcome in the multivariate model (HR: 1.72; 95% CI: 0.89 to 3.33; p = 0.11. Assessment of LBBB contraction pattern was superior to time-to-peak indexes of dyssynchrony (p ;lt& 0.01 for all). Conclusions Contraction pattern assessment to identify true LBBB activation provided important prognostic information in CRT candidates.

Original languageEnglish (US)
Pages (from-to)631-641
Number of pages11
JournalJournal of the American College of Cardiology
Volume66
Issue number6
DOIs
StatePublished - Aug 11 2015

All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine

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