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Under-use of beta-blockers in patients with ischaemic heart disease and concomitant chronic obstructive pulmonary disease

M. Egred, S. Shaw, B. Mohammad, P. Waitt, E. Rodrigues
DOI: http://dx.doi.org/10.1093/qjmed/hci080 493-497 First published online: 13 June 2005

Abstract

Background: Beta-blockers (BB) improve morbidity and mortality in ischaemic heart disease. There is a general reluctance to use BB, especially in patients with chronic obstructive pulmonary disease (COPD), which is perceived as an absolute contraindication. As large numbers of patients are labelled with COPD without objective evidence, they may miss out on the benefit from these drugs.

Aim: To assess the use of BB in patients with COPD admitted with acute coronary syndrome (ACS), and to assess the supporting evidence for the diagnosis of COPD in these patients.

Method: Case-note review and retrospective analysis of 457 consecutive patients admitted with troponin-positive ACS between October 2002 and October 2003.

Results: Of 457 ACS patients studied, 246 (54%) were discharged on a BB. Cardiologists prescribed BB in ACS patients more frequently than did general physicians, (70% vs. 30%, respectively). The reasons for withholding BB were: not documented 27%, COPD 33%, heart failure 24%, others 16%. Ninety-four patients (21%) had a diagnosis of COPD; only 58 (62%) of these had been reviewed by a chest physician or had previous pulmonary function tests. Of the 94 patients with COPD, only 15 (16%) were prescribed BB during the admission: 9 by cardiologists and 6 by non-cardiologists. BB were discontinued in two patients due to an increase in dyspnoea.

Conclusion: Many patients with a diagnosis of COPD have no objective evidence to support the diagnosis and are denied the prognostic benefits of BB when presenting with ACS. Before withholding beta-blockers, COPD and reversibility should be ascertained by pulmonary function testing. The overall use of beta-blockers remains sub-optimal and could be improved in this setting.

Introduction

Beta-adrenergic blocking drugs or beta-blockers (BB) have morbidity and mortality benefits in the management of patients with cardiac disease.1–12 Many patients with chronic obstructive pulmonary disease (COPD) have concomitant conditions such as coronary artery disease (CAD) that require the use of BB. However, despite the clear evidence of the effectiveness of BB, there is a general reluctance to use them in patients with COPD, due to a perceived contraindication and fear of inducing adverse reactions and bronchspasm.5,13–15 This is based mainly on anecdotal evidence and case reports citing acute bronchospasm following the administration of BB.16–20 The safety of BB in patients with COPD has been demonstrated, but their use in this group of patients remains low.21–24

Furthermore, large numbers of patients are labelled with a diagnosis of ‘COPD’ and treated with inhalers despite a lack of objective evidence (such as pulmonary function tests or specialist assessment) to establish the diagnosis, as recommended by the British Thoracic Society. This suggests that a significant number of patients may be inappropriately deprived the prognostic benefits of BB use.25

Our aim was to assess the use of BB in patients with COPD admitted with an acute coronary syndrome (ACS), as well as to assess the supporting evidence for the diagnosis of COPD, such as spirometry or specialist assessment. We also analysed the overall use of BB and the difference in practice in BB use between cardiologists and non-cardiologists.

Methods

We retrospectively analysed the case-notes of patients admitted with a diagnosis of acute coronary syndrome (ACS), including ST-elevation and non- ST-elevation myocardial infarction and unstable angina confirmed with a positive cardiac troponin blood test. Patients who were admitted between October 2002 and October 2003 were identified from the hospital discharge records. Notes were retrieved and reviewed for the index admission and follow-up.

Data were extracted regarding: (i) number of patients with ACS treated and discharged on BB; (ii) documented reasons for withholding BB treatment; (iii) number of patients with ACS labelled with a diagnosis of COPD; (iv) number of patients labelled with COPD who had the diagnosis confirmed by pulmonary function testing or by a chest physician, and the presence of significant reversibility (>15%) after bronchodilators; (v) whether the caring doctor was a cardiologist or non-cardiologist.

All data were extracted by medical staff into a pre-designed pro forma and then entered into the computer by an audit clerk. Twenty-five random sets of notes were crosschecked by a second operator to ensure the accuracy of the data extracted and the absence of discrepancies in recording the information. Data are presented as actual figures and percentages.

Results

Of 457 ACS patients studied, 246 (54%) were discharged on BB. Cardiologists prescribed BB in 70% of ACS patients, compared to a 30% prescription rate by non-cardiologists. The documented reason in the notes for withholding BB was COPD in 33%, heart failure in 24%, and other reasons in 16%. In 27%, no reason was documented (Figure 1).

Figure 1.

Percentage of documented reasons for withholding beta-blockers.

Ninety-four patients (21%) had a label of COPD: 58 (62%) had the diagnosis confirmed by previous pulmonary function testing, of whom 49 (52%) had been seen by a chest physician. Airway reversibility testing was available in only 22 (23%) patients, of whom 13 (12%) showed significant reversibility.

Of the 94 patients labelled as COPD, only 15 (16%) were prescribed BB during the index admission: 9 by cardiologists and 6 by non-cardiologists. BB were discontinued in two out of these 15 due to perceived increased dyspnoea, with no documented objective evidence with repeat pulmonary function testing.

The results are summarized in a flow chart (Figure 2).

Figure 2.

Flow chart of patient according to the presence of COPD.

Discussion

Our study demonstrates that the overall use of BB in patients with troponin-positive ACS remains suboptimal. Cardiologists seem to use BB more often than non-cardiologists, and this may reflect better familiarity with BB use, greater appreciation of the major benefits of BB on mortality and morbidity in ACS patients, and more ease in using BB despite relative contraindications. This raises an important issue about the care of patients admitted with ACS. Ideally, such patients should be managed by cardiologists. This would have a major effect in increasing the use of evidence-based therapy such as BB, thereby improving mortality and morbidity in those patients. Such a strategy would, however, have major implications on the workload of cardiologists.

The study also indicates that many patients with a diagnostic ‘label’ of COPD have no objective evidence to support this diagnosis, and are therefore denied the prognostic benefits of BB when presenting with ACS, despite the established safety of using BB in patients with COPD.19–25 Due to unfounded fears of side-effects, BB are only used in a small proportion of the patients with CAD who would benefit from them.26–29

The most common co-morbid conditions cited for withholding BB in elderly patients after MI are COPD and asthma.30 On the other hand, peripheral arterial and bronchial problems are reported to be the most frequent side-effects.31,,32 This was reflected in our findings. However, in our study, 27% of patients had no documented reason for withholding BB, and this group may well have had some definite contraindications to BB. Heart failure also was documented as a reason for withholding BB in 24% of these patients, contrary to current trends and guidelines, in which BB are important part in the treatment of heart failure. The under-use of BB in COPD patients is based mostly on case reports rather than randomized controlled trials.

Ageing increases the incidence of both COPD and CAD, with CAD reported to co-exist in 10% of COPD patients.33 In our study, CAD and a ‘label’ of COPD co-existed in 21% of patients; this may reflect a high prevalence of smoking as the main cause for COPD in our cohort of patients. Alternatively, it may reflect an inappropriate diagnosis with patients labelled as suffering from COPD with no objective evidence to support the diagnosis.

Bronchoconstriction results from the blockade of β2 receptors, and as a consequence non-selective BB may worsen COPD and asthma. Significant reduction in mortality by the use of BB after MI has been shown in previous studies and meta-analysis.2,4,,5 Cardio-selective BB are 20 times more effective in blocking β1 than β2-receptors, with negligible effect on β2 in therapeutic doses.34 BB have previously been shown to be well tolerated in patients with cardiac disease and concomitant COPD, with no evidence of worsening of respiratory symptoms or FEV1.35–41 It was not possible in this retrospective study to be certain of the type and dose of BB tried in these patients, so no comments can be made on possible non-selective BB causing side-effects and leading to withdrawal of BB. The cumulative evidence from trials and meta-analysis indicates that cardio-selective BB should not be withheld in patients with reactive airway disease or COPD.21–24 Patients with COPD have a high incidence of cardiac events, necessitating careful consideration of prophylactic treatment.5 The benefits of beta blockade in this group would therefore appear to outweigh any potential risk of side-effects, according to the available evidence. However, it has been suggested that evaluation of BB therapy in patients with COPD requires a detailed classification of patients according to the severity of their lung disease.5 Accordingly, the guidelines from the American College of Cardiology-American Heart Association specify ‘severe’ COPD as a contraindication to BB therapy, rather than the mere presence of the condition, regardless of its severity.42

Although our study is a retrospective analysis, the findings are widely applicable and they perhaps should prompt clinicians to question the belief that BB should not be used in patients with any type of contraindication. This is highlighted in the Cooperative Cardiovascular Project pilot study, where more than two-thirds of patients who received BB had one or more relative contraindications.43 In the absence of a proven deleterious effect and absolute contraindication, it is not logical to abandon the use of BB.

We suggest that patients admitted with ACS and concomitant COPD should be tried on BB. A safe approach is to initiate cardio-selective BB at a low dose and titrate them up as tolerated during the hospital admission. This will allow close observation and assessment of tolerance of these medications, and will ensure that these patients are not denied the prognostic benefits of a well-tolerated and effective treatment. It may be necessary to discontinue the drug in few patients because of bronchoconstriction, but, from the published literature, the potential benefit appears large enough to warrant this small risk. Metoprolol is a cardio-selective BB with short half-life, has been shown to be safe and effective in patients with COPD44 and may be the BB of choice to initiating therapy.

Our study is a retrospective analysis of notes with all the inherent limitations. Reliance on the accuracy and completeness of documentation in hospital case-notes should be viewed cautiously, as is evident from the documentation of the reasons for withholding BB. The type (selective vs. non-selective) and dose of the BB used was not easily identified in the notes, and subsequently we could not comment on their contribution to any side-effects, which is likely to be significant. The study was conducted in one centre, but may well reflect the practice in most centres and by most physicians. The number of notes analysed was relatively small, but we surveyed consecutive cases, which would have helped to avoid selection bias.

In conclusion, patients with CAD and concomitant COPD are denied the prognostic benefits of BB when presenting with ACS, despite the lack of objective evidence of COPD and the proven safety of BB in these patients. Clinicians should not withhold BB based on fear of side-effects, and should try to initiate selective BB while the patient is in hospital under their care.

References

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