Beneficial effects of biventricular pacing in chronically right ventricular paced patients with mild cardiomyopathy

To investigate whether cardiac resynchronization therapy (CRT) by means of biventricular (BiV) pacing can improve left ventricular (LV) function, remodelling and clinical status in chronically right ventricular (RV) paced patients with mild cardiomyopathy. Thirty-six chronically (10 +/- 7 years) RV paced patients with left ventricular ejection fraction (LVEF) <40% or LVEDD > 55 mm, without an established indication for CRT, were subjected to 6 months RV and BiV pacing in a patient-blinded, randomized crossover design. Treatment-effects of BiV pacing were evaluated for LV function, LV remodelling and clinical status. As compared with RV pacing, BiV pacing significantly improved LV function (LVEF 46 +/- 12 vs. 39 +/- 12% and LVFS 24 +/- 7 vs. 21 +/- 7%) and reduced LV end-diastolic and end-systolic diameters and volumes (LVEDD 56 +/- 8 vs. 59 +/- 8 mm, LVESD 43 +/- 8 vs. 47 +/- 9 mm, LVEDV 132 +/- 65 vs.144 +/- 62 mL and LVESV 77 +/- 56 vs. 92 +/- 55 mL, respectively). In 19 patients (53%) response to BiV pacing was clinically relevant, defined as LVESV reduction > 15%. BiV pacing also significantly improved NYHA classification. BiV pacing following chronic RV pacing may improve LV function and reverse LV remodelling in patients with relatively mild LV dysfunction or remodelling. Hence, upgrade to BiV pacing might be considered in chronically RV paced patients with mild cardiomyopathy.