176-77: High incidence of hyper-response to optimized dual site left ventricular cardiac resychronization therapy

Introduction: Studies have shown improved reverse LV remodeling with dual site LV CRT in the short term, 3-6 months. This study represents a 5 year follow up of the Dual LV vs Single LV pacing Dual Site Left Ventricular Pacing study. Methods: We followed 39 patients from the Dual Site Left Ventricular Pacing study cohort for >5 years. Population included 27 males, 19 non-ischemics, mean LVEF 27 ±7%. All had LBBB mean QRS 154 msec. All received 2 LV leads. One was positioned mid or basal lateral and the other posterior or antero-lateral, with maximal physical separation. Precise lead placement required positive fixation leads in 15, coronary venous stenting in 12, venoplasty in 4. After baseline echocardiography, half were prospectively randomized to RV+ single LV and the other half to RV+ dual LV cardiac resynchronization therapy (CRT). After 3 months, the groups were crossed over. At study termination (6 months), devices were programmed at the investigator's discretion to RV + dual LV in 35 and RV + single LV (due to high thresholds) in 4. Patients were followed every 3 months for device and medication assessment. Results: At 5 years, LVEF was >50% (mean ±) in 20 patients, LVEF improved by >30% over baseline in 14 patients, there was no improvement in 5 patients and 12 patients died during late follow-up (all 5 who failed to respond to CRT, 5/14 with moderate response and 2/19 with hyper-response). Conclusions: CRT with optimal device programming, medication adjustment, and careful lead placement improved LVEF >30% over baseline in 80% patients. LVEF normalized in 49%. Clinical outcomes paralleled EF response. Multi-branch LV + RV CRT may contribute to hyper-response to CRT.