Effect of beta-blocker therapy on left atrial function in patients with heart failure: comparison of metoprolol succinate with carvedilol
We aimed to compare the effects of carvedilol and metoprolol succinate on left atrial (LA) function in patients with chronic heart failure. Thirty three patients (6 females, 27 males) who had not received β blocker treatment previously and whose left ventricular ejection fraction was below 40% were included in this study. LA volumes were measured echocardiographically just before the time of mitral valve opening (V max), onset of atrial systole (p-wave at the electrocardiography = V p) and mitral valve closure (V min) according to the biplane area length method at baseline and in the 3rd month after the administration of β blockers. NT-proBNP level was measured at the beginning and in the third month of β blocker treatment. The first group was given carvedilol 6.25 mg/day, the second group was given 12.5 mg/day metoprolol succinate and it was increased to the tolerable maximal dose. LA diameter and LA V max, V p, V min decreased significantly both in carvedilol group and metoprolol group after β blocker theraphy (P  < 0.01, P  < 0.01, P  < 0.05, P < 0.05 for metoprolol, P < 0.001, P < 0.01, P < 0.01, P < 0.01 for carvedilol). But it was increased in conduit volume (P < 0.05 for two groups). LA-passive emptying fraction, LA-active emptying fraction and reservoir fraction were no significant differences both in carvedilol group and metoprolol group after β blocker theraphy. NT-proBNP levels were found to decrease significantly in both groups after β blocker treatment (P < 0.001). Our findings indicate that β blocker treatment leads to a decrease in LA diameters and volumes, and metoprolol succinate and carvedilol had similar effects on this decrease.