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β Blockers should be used more widely after myocardial infarction

BMJ 1998; 317 doi: https://doi.org/10.1136/bmj.317.7158.558 (Published 29 August 1998) Cite this as: BMJ 1998;317:558
  1. Alex Brooks
  1. BMJ

    Many more patients would survive a myocardial infarction if β adrenergic blockers were used more widely, according to American researchers.

    Stephen Gottlieb and colleagues from the University of Maryland reviewed 201752 records of patients who had had a myocardial infarction, 34% of whom were prescribed β blockers (New England Journal of Medicine1998;339:489-97).

    As expected, patients in the study with known contraindications were less likely to be given β blockers–for example, very elderly people or those who have low ventricular ejection fraction, chronic obstructive pulmonary disease, diabetes mellitus, or low blood pressure or heart rate. Mortality was lower, however, in every subgroup of patients treated with β blockers than in untreated patients.

    The researchers found that in patients with a myocardial infarction and no other complications treatment with β blockers was associated with a 40% reduction in mortality. Mortality was also reduced by 40% in patients with non-Q wave infarction or chronic obstructive pulmonary disease–conventional contraindications.

    Benefits were less spectacular among patients who were old or black or who had low left ventricular ejection or a high serum creatinine concentration, but the higher mortality among those groups resulted in an absolute reduction of deaths similar to those in lower risk categories.

    In patients aged over 80 years, β blockers reduced mortality by 32%, but only 27% of those aged over 84 received this treatment. Diabetic patients, who are often not treated because of fears that the β blockers would mask hypoglycaemic symptoms, have high mortality after an infarction. The 36% fall in mortality when they were given β blockers thus gave a particularly large survival benefit. The authors concluded that the analysis “strongly indicates that beta-blockade is an underused therapy for patients who have had a myocardial infarction.”

    The study was limited because it was not a randomised controlled trial. It does show, however, what happens in the real world, outside the confines of a trial. In an accompanying editorial Dr Martha Radford and Dr Harlan Krumholz from Yale University School of Medicine praise the authors for investigating understudied patients but criticise the broad groupings of conditions such as “heart failure,” for which results may be significantly altered according to the severity of the condition.

    They believe that the study should not lead to alterations of the recommendations on when to use β blockers, only “prompt clinicians to question the belief that beta-blocker therapy should be avoided for patients with any type of contraindication.”