The short and longer term implications of beta-blocker use in cardiology patients with airways disease
thesisposted on 2023-05-26, 05:49 authored by Cochrane, B
Coronary atherosclerosis and chronic obstructive pulmonary disease (COPD) are highly prevalent, and two of the commonest causes of morbidity and mortality in the Australian population. They share cigarette smoking as an important risk factor, and frequently coexist. Drugs which act on the beta-adrenergic receptor are important therapeutic tools in both diseases. However, beta-receptor antagonists, which are commonly used to treat cardiac disease, theoretically may cause adverse respiratory effects and are traditionally avoided in patients with obstructive airways disease. This work seeks to explore the short and longer term effects of beta-blocker medications, when used for treatment of cardiac disease in patients with coexisting obstructive airways disease. Specifically, the aims of this research are: 1. To estimate the prevalence of coexisting obstructive airways disease amongst patients with cardiac disease 2. To investigate current beta-blocker prescribing practice in patients with obstructive airways disease 3. To document adverse respiratory effects of beta-blocker medications, in terms of symptoms, lung function and other longer term health outcomes. Within 24 hours of hospital admission for suspected cardiac disease, patients were screened for airways obstruction, using spirometry. Spirometry results demonstrated a high level of coexistence of cardiac disease and obstructive airways disease, about twice that cited in previously published estimates. Documentation of beta-blocker prescribing practices within the Royal Prince Alfred Hospital's Cardiology Unit revealed minimal prescription of these medications to patients with previously diagnosed chronic obstructive airways disease and asthma, despite limited evidence of adverse effects of beta-blocker use in such patients. This notably occurred even when guidelines recommended beta-blockade as first line therapy, and where survival benefit was established. However, many patients with obstructive spirometry, but no formal diagnosis of obstructive airways disease, did receive betablockers. Longitudinal analysis of symptom assessment, lung function and health outcomes was performed. Lung function and respiratory symptoms data were collected over a twelve month period and data pertaining to beta-blocker discontinuation, respiratory exacerbations, acute cardiac events and survival were collected over almost six years. There was no indication of a statistically significant adverse beta-blocker effect on lung function, respiratory symptoms or survival but beta-blocker medications did appear to increase respiratory exacerbation rates. This work confirms the very high frequency of obstructive airways disease existing in combination with cardiac disease in an Australian urban population, which had been suspected but not previously documented. However, its major contribution is to provide prospective long term respiratory health outcome data for the use of betablocker medications in this group.
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