October 31, 2012Volume 7 - Issue 44         

DynaMed Weekly Update

For the week ending October 26, 2012

Last week 399 articles were evaluated via DynaMed's Systematic Literature Surveillance and 247 were added to DynaMed content.   

 

Based on the editors' criteria of selecting "articles most likely to change clinical practice," one article of significant interest was selected for the DynaMed Weekly Update.

Feature Article

Beta blocker Use May Not Reduce Mortality, Myocardial Infarction, or Stroke In Patients Without Coronary Artery Disease 

 

Beta blockers have long been a standard of care following myocardial infarction (MI), and their use has been generalized to other forms of coronary artery disease (CAD) for secondary prevention and even to patients with CAD risk factors for primary prevention. Most of the evidence supporting beta blocker use comes from randomized trials in patients with MI or heart failure that were conducted 20 years ago or more. In a 1999 systematic review of 82 randomized trials with 54,234 patients with previous MI, beta blocker use for at least 6 months was associated with a 23% reduction in death (BMJ 1999 Jun 26;318(7200):1730), but, the median publication date of the included trials was 1982 and the duration of follow-up was less than 18 months. In recent years, the more frequent use of reperfusion and revascularization therapies may have decreased the amount of scarring of the myocardium associated with an infarction andthus modified the amount of benefit of beta blockers in these populations.

 

A large, longitudinal study (median follow-up 44 months) assessed the current efficacy of beta blocker treatment in 3 cohorts: 14,043 patients with prior MI, 12,012 patients with CAD but no prior MI, and 18,653 patients with at least 3 cardiovascular risk factors. To compare the effects of beta blocker use vs. no use, a propensity score was calculated for each patient characterizing his or her likelihood for receiving beta blockers based on multiple demographic factors, medical history and use of other medications. About half of the patients in each cohort were included in the propensity-matched analyses.

 

There were no statistically significant differences comparing beta blocker use vs. no use in all-cause mortality or cardiovascular mortality in any of the 3 cohorts (level 2 [mid-level] evidence). For cardiovascular mortality, the hazard ratios were 0.91 (95% CI 0.76-1.09) in the prior MI cohort, 0.90 (95% CI 0.72-1.11) in the CAD without prior MI cohort, and 1.05 (95% CI 0.85-1.30) in the CAD risk factor cohort. The study was not powered for a mortality difference of only 9% so a benefit in the groups with known CAD cannot be excluded. In patients with risk factors for CAD, beta blocker use was associated with trends toward increased risk of both nonfatal MI (p = 0.08) and nonfatal stroke (p = 0.06). There were no significant differences in the rates of nonfatal stroke and nonfatal MI in either the prior MI cohort or CAD without prior MI cohort  (JAMA 2012 Oct 3;308(13):1340).

 

American Heart Association guidelines, updated in 2011, took a more conservative approach to recommendations for beta blocker use. The previous guideline, from 2006, had strongly recommended indefinite beta blocker use in patients with MI, acute coronary syndrome, or left ventricular dysfunction. The current guideline calls for treatment for up to 3 years (class I recommendation [should be given]) with a weaker recommendation for longer treatment (class IIa recommendation [reasonable to give]). The new guideline also lowered its recommendation for beta blockers in patients with other vascular diseases from "reasonable to give" (class IIa) to "may be considered" (class IIb) (Circulation 2011 Nov 29;124(22):2458). Current European guidelines recommend long-term beta blocker use only for patients with left ventricular dysfunction (Eur Heart J2011;32(23):2999).

 

This study is limited by the inherent problems of cohort studies  and the complexity involved with propensity matching, which may also be an inadvertent source of bias. While this study raises questions regarding the optimal use of beta blockers in patients with known CAD it does not seem compelling enough to warrant changes in current recommendations. However, the data would seem to caution against the use of beta blockers in patients with risk factors for CAD but no specific CAD history. In that group, which includes patients being treated for hypertension, alternative agents may be preferred.

 

For more information, see the Coronary artery disease (CAD) topic in DynaMed.     

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About DynaMed Weekly Update

Prepared by the clinician members of the DynaMed Editorial Team, DynaMed Weekly Update is a compilation of one to five articles selected from DynaMed's Systematic Literature Surveillance as articles most likely to change clinical practice.

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CME Information

CREDITS

Physicians:
0.25 AMA PRA Category I Credit(s)™
Family Physicians: 0.25 Prescribed credits
Nurse Practitioners: 0.25 Contact hours
 
Release Date: October 31, 2012
Expiration Date: October 31, 2013
Estimated Completion Time:
15 minutes
 
There is no fee for this activity.

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In order to receive your certificate of participation, you should read the information about this activity, including the disclosure statements, review the entire activity, take the post-test, and complete the evaluation form. You may then follow the directions to print your certificate of participation. To begin, click the CME icon at the end of the article.

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Learning Objectives
 
Upon successful completion of this educational program, the reader should be able to:
 
1. Discuss the significance of this article as it relates to your clinical practice.
 
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Faculty Information
 
Alan Ehrlich, MD - Assistant Clinical Professor in Family Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; Senior Deputy Editor, DynaMed, Ipswich, Massachusetts, USA

Michael Fleming, MD, FAAFP - Assistant Clinical Professor of Family Medicine and Comprehensive Care, LSU Health Science Center School of Medicine, Shreveport, Louisiana, USA; Assistant Clinical Professor of Family Medicine, Department of Family and Community Medicine, Tulane University Medical School, New Orleans, Louisiana, USA; Chief Medical Officer, Amedisys, Inc. & Antidote Education Company

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Dr. Ehrlich, Dr. Fleming, DynaMed Editorial Team members, and the staff of Antidote Education Company have disclosed that they have no relevant financial relationships or conflicts of interest with commercial interests related directly or indirectly to this educational activity.
 

 

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AAFP: Enduring Material activity, DynaMed Weekly Update, has been reviewed and is acceptable for up to 13 Prescribed credits by the American Academy of Family Physicians. AAFP certification begins March 7, 2012. Term of approval is for one year from this date with the option of yearly renewal. Each Weekly Update is worth .25 Prescribed credits. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

  

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