Improvement of exercise capacity and left ventricular diastolic function with metoprolol XL after acute myocardial infarction.
BACKGROUND
Left ventricular (LV) diastolic function predicts and correlates with exercise capacity. Beta-blockers improve exercise capacity and LV diastolic function in patients with severe LV systolic dysfunction in dilated cardiomyopathy. However, information on the effect of metoprolol XL on exercise capacity in relation to LV diastolic function in patients with mild to moderate LV systolic dysfunction after acute myocardial infarction is limited.


METHODS
In a randomized, double-blind, placebo-controlled study of 77 patients, a subgroup of 59 patients with mild to moderate LV systolic dysfunction after acute myocardial infarction were given metoprolol XL (n = 29) or placebo (n = 30). The effects of metoprolol XL on exercise capacity in relation to effects on LV diastolic filling were studied. Two-dimensional Doppler echocardiography and maximal symptom limited bicycle test were performed on days 5 through 7 and after 3 months.


RESULTS
Maximal exercise capacity increased in the metoprolol XL group (124 +/- 30 W vs 135 +/- 29 W) compared with placebo (125 +/- 31 W vs 126 +/- 34 W) (P <.01). E/A ratio decreased, A peak velocity increased, reverse pulmonary flow decreased, and deceleration time was significantly prolonged in the metoprolol XL group. A significant correlation was found between the changes of deceleration time (metoprolol XL: rho = 0.69, P <.0001; placebo: rho = 0.31, P = not significant) and A peak velocity (metoprolol XL: rho = 0.71, P <.0001; placebo: rho = -0.15, not significant) in relation to changes of exercise capacity.


CONCLUSIONS
Metoprolol XL increases exercise capacity after 3 months, and this change seems related to improvement of LV diastolic filling after acute myocardial infarction.
Poulsen
S H
SH
Section of Cardiology, Department of Medicine, Haderslev Hospital, Denmark. steen.hvitfeldt@dadlnet.dk
Jensen
S E
SE
Egstrup
K
K
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D003326:Coronary Circulation; D003971:Diastole; D004311:Double-Blind Method; D015150:Echocardiography, Doppler; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000031:analogs & derivatives* / Q000627:therapeutic use; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology*; D010807:Physical Endurance / Q000187:drug effects*; D016277:Ventricular Function, Left / Q000187:drug effects*
D000319:Adrenergic beta-Antagonists; D008790:Metoprolol