What is the role of cardioselective betablockers in the management of severe heart failure in
ICU?
Cardioselective betablockers (eg. atenolol, metoprolol & practolol) have less effect on the beta·2 receptors (less vasoconstriction and less bronchoconstriction). No specific benefits of any subgroup of beta·blockers bas been confumed inthe management of severe heart failure.
The candidates should be able to discuss the complex role of betablockers in heart failure. The role of betablockers in heart failure management is complex enough outside of the !CU. This has been clarified further in the last few years by publication of articles confirming the benefit of addition of betablockers to the conventional heart failure regimen (ACE inhibitor + diuretics) in the outpatient setting (with decreased symptoms, slowing progression, improving LV function and even improving survival). These benefits have been demonstrated initially with carvedilol (non-selective betablocker) and more recently with metoprolol (cardioselective betablocker). Titration of the medication needs to be slow and judicious. It is unknown whether similar benefits can be obtained in the ICU setting, especially given the beneficial effects of short term administration of inotropic agents in dilated cardiomypoathy.
Betablockers may have some benefit in the setting of tachycardia (mcreased resting sympathetic tone), but many patients may experience worsening of symptoms. Success of treatment ofarrhythmias with betablockade depends upon the magnitude of the coincident decrease ·in contractility (other agents may be preferred eg. amiodarone). Prevention of sudden death (malignant ventricular arrhythmias) may be achieved.
Treatment of myocardial ischaemia with betablockers may have beneficial effects (oxygen
requirements, improved relaxation, decreased arrhythmias).
Betablockade may be beneficial in the setting of hypertrophic cardiomyopathy (with diastolic dysftmction), by decreasing myocardial oxygen consumption, decreasing ischaemia and improving
relaxation (lusitropy).
How about another table?
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Advantages of cardioselective betablockers |
Disadvantages of cardioselective beta blockers |
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Mortality |
Mortality improvement is no different to non-selective beta blockers |
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Contractility |
Decreased contractility; |
Decreased responsiveness to preload |
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Heart rate |
Decreased heart rate = decreased cardiac workload |
Fixed stroke volume x decreased heart rate = poor cardiac output |
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Afterload |
No influence on afterload; maintained good diastolic coronary filling |
No decrease in afterload = no decrease in cardiac work against afterload |
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Myocardial oxygen consumption and cardiac workload |
Decreased myocardial oxygen consumption due to decreased heart rate and contractility |
Decreased exercise tolerance |
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Side effects |
Fewer beta-2 effects, thus no disadvantage in peripheral vascular disease and asthma |
Nightmares, depression, lethargy |
Al-Gobari, Muaamar, et al. "Beta-blockers for the prevention of sudden cardiac death in heart failure patients: a meta-analysis of randomized controlled trials."BMC cardiovascular disorders 13.1 (2013): 52.
Tuunanen, Helena, and Juhani Knuuti. "Metabolic remodelling in human heart failure." Cardiovascular research 90.2 (2011): 251-257.