Relationship between two-dimensional speckle-tracking septal strain and response to cardiac resynchronization therapy in patients with left ventricular dysfunction and left bundle branch block: a prospective pilot study

Abstract

Background: Previous studies have demonstrated variable patterns of longitudinal septal deformation in patients with left ventricular (LV) dysfunction and left bundle branch block. This prospective single center study was designed to assess the relationship between septal deformation patterns obtained by two-dimensional speckle-tracking echocardiography and response to cardiac resynchronization therapy (CRT).

Methods: One hundred one patients with New York Heart Association class II to IV heart failure, LV ejection fractions ≤ 35%, and left bundle branch block underwent echocardiography before CRT. Longitudinal two-dimensional speckle-tracking strain analysis in the apical four-chamber view identified three patterns: double-peaked systolic shortening (pattern 1), early pre-ejection shortening peak followed by prominent systolic stretch (pattern 2), and pseudonormal shortening with a late systolic shortening peak and less pronounced end-systolic stretch (pattern 3). CRT response was defined as a relative reduction in LV end-systolic volume of ≥ 15% at 9-month follow-up. CRT super-response was defined as an absolute LV ejection fraction of ≥ 50% associated with a relative reduction in LV end-systolic volume of ≥ 15% and an improvement in New York Heart Association functional class. Cardiac death or hospitalization for heart failure during follow-up was systematically investigated.

Results: Ninety-two percent of patients with pattern 1 or 2 were responders to CRT compared with 59% with pattern 3 (P < .0001). Thirty-six percent of patients with pattern 1 were super-responders compared with 15% of those with pattern 2 and 12% of those with pattern 3 (P = .037). The improvement in LV volumes, LV ejection fraction, and global longitudinal strain after CRT was better in patients with pattern 1 or 2 compared with those with pattern 3 (P < .0001 for all). Eighteen-month outcomes were excellent in patients with pattern 1 or 2, with event-free survival of 95 ± 3% compared with 75 ± 7% in patients with pattern 3 (P = .010).

Conclusions: Septal deformation strain pattern 1 or 2 is highly predictive of CRT response. Further studies are needed to identify predictors of "nonresponse" in patients with a pattern 3.

Keywords: Cardiac resynchronization therapy; Heart failure; Left bundle branch block; Strain; Two-dimensional echocardiography.