Limitation of myocardial infarct size. Present status

Reporting, updating, and correcting systematic reviews of the effects of health care

The recent growth in the numbers of published systematic reviews reflects growing recognition of their importance for improving knowledge about the effects of health care. In Britain the NHS R&D Programme has established two centres to prepare systematic reviews of existing information, and the Cochrane Collaboration--an international network of individuals and institutions--evolved to produce systematic, periodically updated reviews of randomised controlled trials. The large amount of existing evidence that needs to be considered creates a problem for the reporting of systematic reviews: the need to ensure that methods and results of systematic reviews are adequately described has to be reconciled with the limited space available in printed journals. A possible solution is the use of electronic publications: reviews could be published simultaneously in a short, printed form and in a more detailed electronic form. Electronic publications also have the advantage of the ease with which reviews may be updated as new evidence becomes available or mistakes are identified.

Sudden cardiac death and the potential role of beta-adrenoceptor-blocking drugs

Sudden cardiac death is a major health problem in the industrially developed countries. The risk of sudden cardiac death may be reduced by early detection of coronary heart disease, elimination of the risk factors, treatment of the ischaemia in patients known to have coronary heart disease and suppression of ventricular arrhythmias. Of all the therapeutic measures currently available to reduce the risk of sudden cardiac death, beta-adrenoceptor-blocking drugs (beta blockers) appear to be the most effective. In this paper their actions are reviewed and evidence for their efficacy is presented.

Identification of meta-analyses. The need for standard terminology

Our efforts to identify published articles describing meta-analyses of clinical trials illustrate the need for standard terminology to facilitate retrieval. We found 119 articles describing meta-analyses and eligible for inclusion in MEDLINE, and yet when we searched MEDLINE, using strategies based on textwords and medical subject headings (MeSH), only 48% of the 119 articles were identified. Sixty-eight (57%) of the 119 articles contained at least one of the terms "meta-analysis," "pooling," or "overview" in the title or abstract. The importance of meta-analyses in the evaluation of medical treatments argues for more disciplined use of a specific term in order to facilitate identification of articles. The fact that the National Library of Medicine has started in 1989 to index articles describing meta-analyses using the MeSH META-ANALYSIS underscores this argument.

Early use of beta-adrenergic-blocking agents in acute myocardial infarction

Of recent interest is the acute use of beta-adrenergic-blocking agents in patients who have suffered an acute myocardial infarction (AMI). Acute use of beta-blockers refers to initiation of therapy within hours following the onset of symptoms suggestive of AMI. The proposed goal of therapy is to alter the infarction process to improve mortality. Because of the hyperadrenergic activity present in patients during an infarction, beta-blockers are theoretically an attractive therapeutic intervention because of their sympatholytic properties. Acute use of beta-blockers has been shown to limit infarct size, as determined by cardiac enzyme activity, and reduce the incidence of major ventricular arrhythmias. Beta-blockers may also prevent infarction in patients with symptoms suggestive of infarction. However, the acute use of beta-adrenergic-blocking agents has not been shown to reduce short-term (less than or equal to 30 d) mortality. In view of this fact, the acute use of beta-adrenergic-blocking agents cannot be recommended.