Long-Term Effects of Upgrading to Biventricular Pacing: Differences with Cardiac Resynchronization Therapy as Primary Indication

BACKGROUND: Few studies have assessed the long-term effects of cardiac resynchronization therapy (CRT) in patients with advanced heart failure (HF) and previously right ventricular apical pacing (RVAP). AIMS: To assess the clinical and hemodynamic impact of upgrading to biventricular pacing in patients with severe HF and permanent RVAP in comparison with patients who had CRT implantation as initial therapy. METHODS AND RESULTS: Thirty-nine patients with RVAP, advanced HF (New York Heart Association NYHA III-IV), and severe depression of left ventricular ejection fraction (LVEF) were upgraded to biventricular pacing (group A). Mean duration of RVAP before upgrading was 41.8 +/- 13.3 months. Clinical and echocardiographic results were compared to those obtained in a group of 43 patients with left bundle branch block and similar clinical characteristics undergoing "primary" CRT (group B). Mean follow-up was 35 +/- 10 months in patients of group A and 38 +/- 12 months in group B. NYHA class significantly improved in groups A and B. LVEF increased from 0.23 +/- 0.07 to 0.36 +/- 0.09 (P < 0.001) and from 0.26 +/- 0.02 to 0.34 +/- 0.10 (P < 0.001), respectively. Hospitalizations were reduced by 81% and 77% (P < 0.001). Similar improvements in echocardiographic signs of ventricular desynchronization were also observed. CONCLUSION: Patients upgraded to CRT exhibit long-term clinical and hemodynamic benefits that are similar to those observed in patients treated with CRT as initial strategy.