title: Heart rate dependency of cardiac performance in heart failure patients treated with metoprolol.
abstract: OBJECTIVE
  To investigate whether a low heart rate is necessary to maintain improvement in myocardial function after long-term treatment with a beta-blocker in patients with heart failure.
  
  
  RESULTS
  Forty-eight patients with congestive heart failure were investigated: 30 patients with dilated cardiomyopathy participating in a placebo-controlled trial (15 on placebo, 15 on metoprolol), and 18 patients treated by metoprolol in an open protocol. Investigations of spontaneous heart rate and of matched paced heart rates were performed at baseline and after 3, 6 and 12 months of follow-up by radionuclide angiography. There were significant signs of improvement in systolic indices of the spontaneous heart rate in the metoprolol-treated group (peak ejection rate: 0.98 to 1.32 end-diastolic volume.s-1, P = 0.015) as compared to placebo (1.14 to 1.19 end-diastolic volume.s-1, not significant). Similar effects were observed during the matched paced heart rate (peak ejection rate: metoprolol 0.91 to 1.38 end-diastolic volume.s-1, P = 0.037; placebo 1.22 to 1.12 end-diastolic volume.s-1, not significant). No effects were observed in the early peak filling rate. Left ventricular volumes decreased during metoprolol treatment, both for the spontaneous heart rate and during matched pacing.
  
  
  CONCLUSIONS
  These data imply that beta-blocker treatment improves the force-frequency relationship of myocardial performance. A lower heart rate is not necessary to maintain cardiac function on a short-term basis, once myocardial recovery has occurred.
authors.affiliation: Wallenberg Laboratory for Cardiovascular Research, Department of Cardiology, University Hospital, Göteborg, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Andersson
authors.forename: S O
authors.initials: SO
authors.lastname: Strömblad
authors.forename: M
authors.initials: M
authors.lastname: Lomsky
authors.forename: F
authors.initials: F
authors.lastname: Waagstein
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D002302:Cardiac Output / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000494:pharmacology / Q000627:therapeutic use*; D008875:Middle Aged; D015996:Survival Rate; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D000319:Adrenergic beta-Antagonists; D008790:Metoprolol