PURPOSE:The benefit of Carvedilol (Carv) compared to Metoprolol (Meto) in patients with left ventricular mechanical dyssynchrony (LVMD) receiving cardiac resynchronization therapy (CRT) has not been well delineated. The effect of maximum tolerated dose of these drugs on cardiac function, LVMD and response to CRT was studied.
METHODS:We studied 97 consecutive patients with CRT (male 70, age 69.7± 9.5 years). Patients with atrial fibrillation were excluded. Patients were divided into Group I, 31 patients on Carv (dose 22.3± 17.1mg/d, 27 patients started 23.3± 29.6 months before CRT and all continued for 20.0± 11.0 months after CRT) and Group II, 66 patients on Meto (dose 60.4± 43.3mg/day, 56 patients on Succinate, 10 patients on Tartrate, 52 patients started 21.5± 25.0 months before CRT and all continued for 21.6± 12 months after CRT). The time difference (TPW-TDI) between QRS onset to the end of LV ejection by pulsed wave Doppler (PW) and QRS onset to the end of the systolic wave in basal lateral and septal segments with greatest delay by tissue Doppler imaging (TDI) was measured before CRT and 15.1 ± 10.6 months after CRT. TPW-TDI > 50ms was defined as LVMD. A decrease of left ventricular end systolic volume ≥15% after CRT was defined as a positive response to CRT.
RESULTS:During follow-up by echo/Doppler studies, patients on Meto had greater improvement in LVEF (19.7± 6.6% to 27.9± 13.6%, p< 0.0001) than in patients on Carv (22.3± 6.8% to 25.7± 12.0%, p=0.17). More patients on Meto (35/66, 53%) responded to CRT compared to patients on Carv (9/31, 29%, p< 0.05). TPW-TDI significantly decreased in both groups (p< 0.0001 and p= 0.01). There were no significant differences in mortality and hospitalization between these two groups (p= NS).
CONCLUSION:Positive response to CRT and improvement of cardiac function is significantly greater in Meto compared to Carv.
CLINICAL IMPLICATIONS:The study demonstrated the impact of Metoprolol in patients with CRT.
DISCLOSURE:Chandra Nair, None.