Introduction: The Dual Site LV Pacing study was a randomized, prospective, single center trial comparing dual LV +RV CRT with standard single LV CRT, with LV lead in optimal mid/basal lateral position.

Methods: Thirty-nine patients (23 male) mean LVEF 27 ±10, 20 ischemic, NSR, LBBB, meeting standard CRT criteria, were randomized to single LV+RV (s-CRT) or Dual LV+RV CRT(dCRT), and crossed over after 3 months to the other arm. Medications and AV intervals were carefully optimized. One LV lead was positioned mid or basal lateral, and the other anterior or posterior lateral closer to the apex. Maximal physical LV lead separation was attempted, requiring a positive fixation lead (15), retaining coronary venous stents ( 12 ), coronary venoplasty ( 4). Echocardiograms performed at baseline, after 3 months, and 6 months were interpreted by a blinded echocardiographer.

Results: After 3 months, there was a greater percentage increase in EF in d-CRT (51%) than s-CRT (42%), although this difference was not significant.After crossover, ther was similar further increase in LVEF % in both groups (4% vs 7%).

Conclusions: d-CRT may produce greater reverse remodeling than s-CRT, although this difference may be marginal when the LV lead in s-CRT is positioned in the “optimal” basal/mid lateral position.