Use of β blockers in patients with COPD

Chronic obstructive pulmonary disease (COPD) is the leading cause of respiratory-related deaths in the USA.1 This simple and dramatic statistic, however, does not present the full story. In developed countries, smoking tobacco is the principal cause of COPD and also represents a major risk factor for other conditions such as cardiovascular disease and lung cancer.2 One question that remains largely unanswered is how the presence of COPD modifies the treatment of coexisting illnesses such as cardiovascular disease. This question is important because most patients with COPD do not die of COPD but, as demonstrated by randomised trials and observational studies, the principal causes of death are most often listed as cardiovascular-related or lung cancer-related.3^–5 Tension in treatment decisions often occurs when clinicians must decide about providing patients with treatments that are known to improve outcomes for selected patients while potentially causing harm in others. A paradigm for this dilemma is the use of β blockers in patients with COPD.

Beta blockers are first-line therapy for patients with cardiovascular disease and have been shown in randomised clinical trials to reduce mortality.6^–8 The strongest evidence for the mortality benefit of β blockers is in myocardial infarction,6^–8 ischaemia8 and left ventricular systolic dysfunction,9 10 but there are a number of other settings including hypertension,11^–13 tachyarrhythmia,14 perioperative risk modification15 16 and thyrotoxicosis.17^–19 Although there are many potential explanations for the reduction in mortality, the benefit is clear. Beta blockers, by their effect on the β adrenoceptor, decrease myocardial contractility, chronotropic response and myocardial oxygen demand.20 In the setting of myocardial ischaemia, these effects reduce overall myocardial injury.21^–23 …