11. Cardiac Resynchronization Therapy: Different Issues11.7 Left Ventricular Functional Deterioration and Worsening in NYHA Class After Right Ventricular Pacing is Improved by Upgrading to Biventricular Stimulation in Patients with Different Degrees of Baseline Dysfunction

Worsening in NYHA Class and left ventricular (LV) systolic function is reported in right ventricular (RV) paced patients (pts); improvement in LV function can be expected after LV lead placement. Aim of this study was to assess in pts with LV dysfunction whether RV pacing affects clinical/functional parameters and the role of LV lead placement. 18/100 pts referred for CRT underwent upgrading to biventricular stimulation: 14 DDD, 4 VVI, 2-180 months before upgrading. Before conventional PM pts were in NYHA Class 2.5 ± 0.8; LV ejection fraction (EF) was 30.5 ±10.4 (19 - 46%). CRT was performed for worsening heart failure. Before CRT pts were in NYHA Class 3.2 ± 0.5; LVEF 24±5.2% (p<.05 vs before RV implantation). At 3-18 months follow-up, NYHA class increased to 2.1 ± 0.3 with an increase in LVEF to 29 ± 4% (p<.05 vs pre-upgrading). In pts with baseline LV dysfunction, RV pacing worsens NYHA Class and LVEF. Upgrading to CRT improves clinics and function. CRT should be a first choice treatment in pts with LV dysfunction who need RV pacing for clinical reasons.