Effect of metoprolol on rest and exercise left ventricular systolic and diastolic function in idiopathic dilated cardiomyopathy.
OBJECTIVE
To further characterize the effects of heart rate on systolic and diastolic function in patients with idiopathic dilated cardiomyopathy (IDCM), it was hypothesized that the relationship between heart rate and left ventricular systolic and diastolic function would be unaltered by beta-blockade and exercise.


METHODS
Eighteen patients with IDCM were randomized in a double-blind manner to receive either metoprolol or placebo for 3 months. Before and after 3 months of therapy, resting and exercise radionuclide left ventriculograms were obtained for assessment of left ventricular systolic and diastolic function.


RESULTS
At rest, metoprolol treatment compared with placebo was associated with decreased heart rate (61 +/- 11 vs 99 +/- 10 beats/min, P <.0001) and an increased left ventricular ejection fraction (0.32% +/- 0.10% vs 0.17% +/- 0.08%, P =.01). With exercise, metoprolol compared with placebo caused a decreased heart rate (86 +/- 18 vs 126 +/- 43 beats/min, P =.056), an increase in left ventricular ejection fraction (0.32% +/- 0.14% vs 0.19% +/- 0.07%, P =.052), a longer time to peak filling rate (164 +/- 21 vs 127 +/- 17 ms, P =.005), and a decreased peak filling rate (5.41 +/- 1.71 vs 8.40 +/- 1.85 stroke volumes/s, P =.012). Before beta-blockade, heart rate at rest was negatively correlated to left ventricular ejection fraction and positively correlated to peak filling rate; with exercise, the relationships of heart rate to left ventricular ejection fraction and peak filling rate were similar. After metoprolol treatment, the heart rate continued to have a similar positive correlation with the peak filling rate at rest and with exercise.


CONCLUSIONS
In patients with IDCM, systolic and diastolic cardiac function, at rest and with exercise, was related to heart rate. After beta-blockade, at rest and with exercise, diastolic function continued to be related to heart rate.
Clements
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IP
Division of Cardiovascular Disease and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minn.
Miller
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D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D003971:Diastole / Q000187:drug effects; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000627:therapeutic use*; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D015635:Radionuclide Ventriculography; D012146:Rest; D013318:Stroke Volume / Q000187:drug effects; D013599:Systole / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects*
D000319:Adrenergic beta-Antagonists; D008790:Metoprolol