Case 1:

JF is a 42-year old previously healthy farmer who presented with sudden onset central chest pain of one hour duration to the ED. The pain is associated with sweating and radiates to the left arm and jaw. The area of discomfort is about the size of the fist.

Ragavendra R. Baliga, M.D
Assistant Professor
Division of Cardiology
University Of Michigan

 

Main Index

Table Of Contents

Question 27 of 39:

Beta-blocker therapy is not indicated in this patient because he has successfully undergone reperfusion with thrombolytics.

You clicked 'False'

Correct!

Patients without a contraindication to beta-blocker therapy who can be treated within 12 hours of onset of infarction, irrespective of administration of concomitant thrombolytic therapy or performance of primary angioplasty.

Other indications for beta-blockers include patients with continuing or recurrent ischemic pain and patients with tachyarrhythmias, such as atrial fibrillation with a rapid ventricular response.

Beta-blockers may be given to patients with acute MI to reduce morbidity and/or mortality during

  • the initial hours of evolving infarction
  • the weeks, months and years after completed infarction (secondary infarction).

During the first few hours of infarction, ß-adrenergic blocking agents may diminish myocardial oxygen demand by reducing heart rate, systemic arterial pressure and myocardial contractility. In addition, prolongation of diastole caused by reduction in heart rate may augment perfusion to injured myocardium, particularly the subendocardium. As a result, immediate ß-adrenoreceptor blocker therapy appears to reduce

  • the magnitude of infarction and incidence of associated complication in subjects not receiving concomitant thrombolytic therapy and
  • the rate of reinfarction in patients receiving thrombolytic therapy.

In subjects not receiving thrombolytic therapy, intravenously administered ß-adrenoreceptor blocking agents exert a modestly favorable influence on infarct size. More importantly they diminish short term mortality. In subjects receiving concomitant thrombolytic therapy intravenously administered beta-adrenoreceptor blocking drugs diminish the incidence of subsequent nonfatal myocardial infarction and recurrent ischemia; in addition they may reduce mortality if given particularly early (within 2 hours) after onset of symptoms.

 
 
Produced by the Learning Resource Center Office of Medical Education University of Michigan Medical School
Copyright 2001 by the University of Michigan Board of Regents. All rights reserved.