Effect of Low-amplitude Two-dimensional Radial Strain at Left Ventricular Pacing Sites on Response to Cardiac Resynchronization Therapy

Background: Left ventricular (LV) lead placement to areas of scar has detrimental effects on response to cardiac resynchronization therapy (CRT). Speckle-tracking radial two-dimensional strain offers assessment of the extent of regional myocardial deformation. The aim of this study was to assess the impact of LV lead placement at areas of low-amplitude strain on CRT response.

Methods: The optimal cutoff of radial strain amplitude at the LV pacing site associated with an unfavorable CRT response was determined in a derivation group (n = 65) and then tested in a second consecutive validation group (n = 75) of patients with heart failure. Patients had concordant LV leads if placed at the most delayed site, and dyssynchrony was defined as anteroseptal to posterior delay ≥ 130 msec. CRT response was defined as a ≥15% reduction in LV end-systolic volume at 6 months.

Results: In the derivation group, a derived cutoff for radial strain amplitude of <9.8% defined low-amplitude segments (LAS) and had a high specificity but low sensitivity for predicting LV reverse remodeling, suggesting a strong negative predictive value. In the validation group, compared with patients without LAS at the LV pacing site, in patients with LAS (n = 16), CRT response was significantly lower (62.7% vs 31.3%, P < .05). By multivariate analysis, LV lead concordance and the absence of an LAS at the LV pacing site but not dyssynchrony were significantly related to CRT response.

Conclusion: LV lead placement over segments with two-dimensional radial strain amplitudes <9.8% is associated with poor outcomes of CRT.