Abstract 3788: Effect of Low Amplitude 2D Radial Strain at Left Ventricular Pacing Sites on Response to Cardiac Resynchronization Therapy
Introduction Left ventricular (LV) lead placement to areas of scar has detrimental effects on response to resynchronization therapy (CRT). Speckle tracking 2D radial strain offers assessment not only on the timing but also on the extent of regional myocardial deformation which will be attenuated in non viable areas. We hypothesised that low amplitude radial strain at the LV pacing site would have detrimental effects on CRT response. We assess the relationship between LV lead placement at areas of low amplitude strain and LV dyssynchrony on CRT response.
Methods Radial 2D strain speckle tracking analysis was performed in 38 patients with heart failure prior to scheduled CRT (age 65 +/− 8 years, 21 ischemic, QRS 152 +/− 14ms, NYHA III/IV 35/3, EF 23 +/− 7%). Following implant, all patients underwent AV and VV delay optimization. The position of the LV lead was determined by biplane fluoroscopy and combined with the speckle data, the paced segment was determined. For the paced segment in each patient we determined the radial strain amplitude and defined low amplitude segments (LAS) as those with a peak radial strain of <10%. LV dyssynchrony was defined as previously reported by anteroseptal to posterior wall radial strain delay of >130ms. Response to CRT was defined as a >15% reduction in left ventricular end systolic volume (LVESV) at 3 months.
Results Response to CRT was seen in 21/38 patients. The LV lead was pacing a LAS in 7 of the 38 patients. In contrast to patients where the LV lead was pacing segments with a strain amplitude of >10%, the response rate in patients where the LV lead was positioned over a LAS was significantly lower (68% vs 0%, p<0.01). In patients with dyssynchrony but no LAS at the LV pacing site, the response rate was 85% which reduced to 0% in patients with LAS at the pacing site (p<0.01). In patients without dyssynchrony and no LAS at the LV pacing site, the response rate was 34% reducing to 0% in patients with LAS at the pacing site (p<0.01).
Conclusion LV lead placement over segments with a 2D radial strain amplitude of <10% is associated with poor outcomes following CRT. This has important implications for attempting to prospectively position LV leads.