Beneficial Effects of Upgrading from Right Ventricular Pacing to Cardiac Resynchronization Therapy in Patients with Heart Failure Compared to de Novo Cardiac Resynchronization Therapy

Background: The effects of upgrading from right ventricular (RV) pacing to cardiac resynchronization therapy (CRT) in patients with heart failure remains unclear. The aim of this study was to evaluate the improvement of cardiac function in patients upgraded from RV pacing to CRT.Methods: We studied 48 consecutive patients who underwent CRT implantation, and were followed up for more than 6 months. This group included 15 patients who were upgraded from RV pacing. We measured left ventricular (LV) dp/dt to determine the timing of LV-RV sequential pacing. Echocardiographic examination was performed before and 6–12 months after the CRT procedure to assess the LV ejection fraction (LVEF).Results: In overall patients, LVEF increased after CRT (31.4 ± 9.8 vs. 37.1 ± 13.6%, p = 0.005). The increase of LVEF was more significant in the upgrade group (31.3 ± 9.4% to 41.9 ± 13.9%, p = 0.01) than in the newly implanted group (31.5 ± 10.1% to 35.0 ± 13.1%, p = 0.13). An increase of dp/dt during CRT was significantly positively associated with an increase of LVEF (r = 0.74, p = 0.01) in overall patients.Conclusion: The upgrading from RV pacing to CRT was associated with greater improvement of LV systolic function than de novo CRT implantation. The change of dp/dt might be useful to predict the improvement of LV systolic function.