Inhaled beta-2 adrenergic receptor agonists and primary cardiac arrest

[Cardiac arrest under special circumstances]

These guidelines of the European Resuscitation Council (ERC) Cardiac Arrest under Special Circumstances are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required for basic and advanced life support for the prevention and treatment of cardiac arrest under special circumstances; in particular, specific causes (hypoxia, trauma, anaphylaxis, sepsis, hypo-/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), specific settings (operating room, cardiac surgery, cardiac catheterization laboratory, dialysis unit, dental clinics, transportation [in-flight, cruise ships], sport, drowning, mass casualty incidents), and specific patient groups (asthma and chronic obstructive pulmonary disease, neurological disease, morbid obesity, pregnancy).

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Development of Myocardial Infarction in a 12-Year-Old Female after the Use of Inhaled Salbutamol

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) accounts for 0.023% of all cases reported in pediatric patients. According to literature, only a handful of ALCAPA patients are able to reach adulthood. Clinical manifestations of ALCAPA range from fatigue during exercise to sudden death in adulthood. Herein, we described a 12-year-old symptomatic patient with ALCAPA who had severe chest pain after using salbutamol treatment for presumed asthma. ALCAPA is one of the curable versions of myocardial ischemia and infarction in childhood. Due to clinical findings in conjunction with electrocardiogram and echocardiography, a computed tomography scan with coronary angiography was performed and the diagnosis of ALCAPA was confirmed. We presented this case because ALCAPA-related myocardial ischemia and infarction in children are rare with only sporadic cases reported. This case illustrated the need for close monitoring and surgery as the best treatment for ALCAPA associated with myocardial infarction.

Therapeutic effects of the combination of inhaled beta2-agonists and beta-blockers in COPD patients with cardiovascular disease

Chronic obstructive pulmonary disease (COPD) is a major health problem worldwide, with co-morbidities contributing to the overall severity and mortality of the disease. The incidence and prevalence of cardiovascular disease among COPD patients are high. Both disorders often co-exist, mainly due to smoking, but they also share common underlying risk factors, such as aging and low-grade systemic inflammation. The therapeutic approach is based on agents, whose pharmacological properties are completely opposed. Beta2-agonists remain the cornerstone of COPD treatment due to their limited cardiac adverse effects. On the other hand, beta-blockers are administered in COPD patients with cardiovascular disease, but despite their proven cardiac benefits, they remain underused. There is still a trend among physicians over underprescription of these drugs in patients with heart failure and COPD due to bronchoconstriction. Therefore, cardioselective beta-blockers are preferred, and recent meta-analyses have shown reduced rates in mortality and exacerbations in COPD patients treated with beta-blockers.

Multimorbidity and COPD Medication Receipt Among Medicaid Beneficiaries With Newly Diagnosed COPD

BACKGROUND

Multimorbidity is highly prevalent among patients with COPD. The association between multimorbidity and COPD medication management is not well researched. The aim of this study was to examine the association between multimorbidity and COPD medication receipt among Medicaid beneficiaries with newly diagnosed COPD.

METHODS

A retrospective longitudinal dynamic cohort design was used, and data were extracted from Medicaid Analytic eXtract files from 2005 to 2008. Medicaid beneficiaries with newly diagnosed COPD (N = 19,060) were identified using the International Classification of Diseases, 9th Revision, Clinical Modification, for COPD. This code (for commonly co-occurring conditions with COPD) was used to create a multimorbidity variable. These conditions included anxiety, arthritis, bipolar disorder, cardiovascular diseases, depression, diabetes, hypertension, hyperlipidemia osteoporosis, and schizophrenia. Medicaid beneficiaries with newly diagnosed COPD were categorized as: (1) physical multimorbidity only, (2) psychiatric multimorbidity only, (3) both physical and psychiatric multimorbidity, and (4) no multimorbidity. Receipt of COPD medications (short- or long-acting bronchodilators, inhaled corticosteroids) was identified using National Drug Codes. Bivariate relationships between multimorbidity and COPD medication receipt were tested using the chi-square test of independence. The associations between multimorbidity and COPD medication receipt were analyzed with logistic and multinomial logistic regression analyses.

RESULTS

Among Medicaid beneficiaries with newly diagnosed COPD, 81.9% had at least one co-occurring chronic condition. After controlling for subject characteristics, adults with multimorbidity were less likely to receive COPD medications compared with those without any inflammation-related multimorbidity. For example, those with physical multimorbidity were less likely to receive short-acting bronchodilators (adjusted odds ratio [OR] 0.76, 95% CI 0.69-0.83), long-acting bronchodilators (adjusted OR 0.84, 95% CI 0.76-0.92), and inhaled corticosteroids (adjusted OR 0.75, 95% CI 0.68-0.82) compared with those with no inflammation-related multimorbidity.

CONCLUSIONS

The prevalence of multimorbidity is very high among Medicaid beneficiaries with newly diagnosed COPD. Our findings indicate poor COPD medication management among those with multimorbidity.

Asthma medications should be available for over-the-counter use: con

The United States Food and Drug Administration recently considered a policy to transfer inhaled short-acting bronchodilators to over-the-counter status if conditions of safe use can be established. The American Thoracic Society filed a comment in opposition to the proposal. This article examines the negative consequences that might result from allowing nonprescription access to bronchodilators and other inhaled asthma medications. Such a proposed policy change conflicts directly with current guidelines for asthma management and would undermine efforts to achieve adequate asthma control in patients. In addition, a policy change to convert asthma medications to over-the-counter status could result in increased costs to patients as well as increased health care costs to society overall due to a worsening of asthma control in the population.

Association of ozone and particulate air pollution with out-of-hospital cardiac arrest in Helsinki, Finland: evidence for two different etiologies

Out-of-hospital cardiac arrest (OHCA) has been previously associated with exposure to particulate air pollution. However, there is uncertainty about the agents and mechanisms that are involved. We aimed to determine the association of gases and particulates with OHCA, and differences in pollutant effects on OHCAs due to acute myocardial infarction (AMI) vs those due to other causes. Helsinki Emergency Medical Services provided data on OHCAs of cardiac origin (OHCA_Cardiac). Hospital and autopsy reports determined whether OHCAs were due to AMI (OHCA_MI) or other cardiac causes (OHCA_Other). Pollutant data was obtained from central ambient monitors. A case-crossover analysis determined odds ratios (ORs) for hourly lagged exposures (Lag 0-3) and daily lagged exposures (Lag 0d-3d), expressed per interquartile range of pollutant level. For OHCA_Cardiac, elevated ORs were found for PM(2.5) (Lag 0, 1.07; 95% confidence interval (CI): 1.01-1.13) and ozone (O(3)) (Lag 2d, 1.18; CI: 1.03-1.35). For OHCA_MI, elevated ORs were found for PM(2.5) (Lag 0, 1.14; CI: 1.03-1.27; Lag 0d, 1.17; CI: 1.03-1.33), accumulation mode particulate (Acc) (Lag 0d, 1.19; CI: 1.04-1.35), NO (Lag 0d, 1.07; CI: 1.01-1.13), and ultrafine particulate (Lag 0d, 1.27; CI: 1.05-1.54). For OHCA_Other, elevated ORs were found only for O(3) (Lag 1d, 1.26; CI: 1.07-1.48; Lag 2d, 1.30; CI: 1.11-1.53). Results from two-pollutant models, with one of the pollutants either PM(2.5) or O(3), suggested that associations were primarily due to effects of PM(2.5) and O(3), rather than other pollutants. The results suggest that air pollution triggers OHCA via two distinct modes: one associated with particulates leading to AMI and one associated with O(3) involving etiologies other than AMI, for example, arrhythmias or respiratory insufficiency.

Pathophysiological relevance of the cardiac β2-adrenergic receptor and its potential as a therapeutic target to improve cardiac function

β-adrenoceptors are members of the G protein-coupled receptor superfamily which play a key role in the regulation of myocardial function. Their activation increases cardiac performance but can also induce deleterious effects such as cardiac arrhythmias or myocardial apoptosis. In fact, inhibition of β-adrenoceptors exerts a protective effect in patients with sympathetic over-stimulation during heart failure. Although β(2)-adrenoceptor is not the predominant subtype in the heart, it seems to importantly contribute to the cardiac effects of adrenergic stimulation; however, the mechanism by which this occurs is not fully understood. This review summarizes the current knowledge on the role of β(2)-adrenoceptors in the regulation of cardiac contractility, metabolism, cardiomyocyte survival and cardiac arrhythmias. In addition, therapeutic considerations relating to stimulation of the β(2)-adrenoceptor such as an increase in cardiac contractility with low arrythmogenic effect, protection of the myocardium again apoptosis or positive regulation of heart metabolism are discussed.

Impact of chronic obstructive pulmonary disease severity on symptoms and prognosis in patients with systolic heart failure

BACKGROUND

Systolic heart failure (SHF) and chronic obstructive pulmonary disease (COPD) are frequently associated. The purpose of our study was to explore the impact of COPD severity on symptoms and prognosis in patients with SHF.

METHODS AND RESULTS

Chronic obstructive pulmonary disease was systematically screened by spirometry in 348 patients admitted for SHF from April 2002 to December 2006. Severity of COPD was defined according to the GOLD classification. Prevalence of COPD was 37.9 %. Patients' distribution according to GOLD stages I, II, II and IV were, respectively, 51.5, 37.9, 7.6 and 3.0 %. Severity of dyspnoea increases with GOLD stage. There was a significant correlation between NYHA stage and left ventricular ejection fraction in patients without COPD (R (2) = 0.03; P = 0.01) but not in patients with COPD. Mean follow-up was of 54.9 ± 27.4 months. Mortality was 46.6 % and was highest in the COPD group (53.8 vs. 42.3 %; P = 0.049). Kaplan-Meier survival curves showed that patients with GOLD stage I had the same prognosis than patients without COPD and mortality increased from GOLD stage II to stage IV. After multivariate analysis, GOLD stage and diuretics' dose were independently associated with mortality.

CONCLUSIONS

Chronic obstructive pulmonary disease is frequent in patients with SHF and increases mortality. Since dyspnoea is poorly specific of COPD in chronic heart failure patients, COPD remains underdiagnosed thus leading to inappropriate increase of diuretics' dose. COPD should be systematically screened in patients with SHF to adapt prescription of selective β1-blockers, and diuretics' dose and reduce the exposition to risk factors.

Are beta2-agonists responsible for increased mortality in heart failure?

AIMS

Previous large-scale, retrospective studies have shown increased mortality in heart failure (HF) patients using β2-agonists (B2As). We further examined the relationship between B2A use and mortality in a well-characterized population by adjusting for natriuretic peptide levels as a measure of HF severity.

METHODS AND RESULTS

This was a retrospective cohort study of patients attending an HF Disease Management Programme with mean follow-up of 2.9 ± 2.4 years. Chart review confirmed B2A use, dose and duration of use, and documented pulmonary function evaluation. The primary endpoint was the effect of B2A use compared with no B2A use on mortality using unadjusted and adjusted Kaplan-Meier survival curves. Data were available for 1294 patients (age 70.6 ± 11.5 years) of whom 64% were male and 22.2% were taking B2As. β2-Agonist users were older, more likely to be male, to have smoked, to have chronic obstructive pulmonary disease (COPD) and asthma, and less likely to take beta-blockers. Multivariable associates of mortality included: B-type natriuretic peptide (BNP), coronary artery disease, age, and beta-blocker use. Unadjusted mortality rates for B2A users were found to be significantly higher than non-B2A users [hazard ratio (HR) 1.304, 95% confidence interval (CI) 1.030-1.652, P= 0.028]. However, when adjusted for age, sex, medication, co-morbidity, smoking, COPD, and BNP differences, overall mortality rates were similar [HR 1.043, 95% CI (0.771-1.412), P= 0.783].

CONCLUSION

Unlike previous reports, this retrospective evaluation of B2A therapy in HF patients shows no relationship with long-term mortality when adjusted for population differences including BNP.  Large, prospective studies are required to define the risk/benefit ratio of B2As in patients with heart failure.

The increase in rat ventricular automaticity induced by salbutamol is mediated through β(1)- but not β(2)-adrenoceptors: role of phosphodiesterases

AIMS

While β(2)-adrenoceptor (AR) agonists are useful bronchodilators, they also produce cardiac arrhythmias. These agents are not fully selective and also activate β(1)-AR, but the involvement of β(1)-AR and β(2)-AR in the observed pro-arrhythmic effect has not been established. We studied the effect of β(1)-AR and β(2)-AR activation on ventricular automaticity and the role of phosphodiesterases (PDE) in regulating this effect.

MAIN METHODS

Experiments were performed in the spontaneously beating isolated right ventricle of the rat heart. We also measured cAMP production in this tissue.

KEY FINDINGS

The β(2)-AR agonist salbutamol (1-100 μM) produced a concentration-dependent increase in ventricular automaticity that was not affected by 50nM of the β(2)-AR antagonist ICI 118551. This effect was enhanced by the non-selective PDE inhibitor theophylline (100 μM) and by the selective PDE4 inhibitors rolipram (1 μM) and Ro 201724 (2 μM), but not modified by the selective PDE3 inhibitors cilostamide (0.3 μM) or milrinone (0.2 μM). The effects of salbutamol alone and in the presence of either theophylline or rolipram were virtually abolished by 0.1 μM β(1)-AR antagonist CGP 20712A. Salbutamol (10 μM) increased the cAMP concentration, and this effect was abolished by CGP 20712A (0.1 μM) but enhanced by theophylline (100 μM) or rolipram (1 μM). Cilostamide (0.3 μM) failed to modify the effect of salbutamol on cAMP concentration.

SIGNIFICANCE

These results indicate that the increase of ventricular automaticity elicited by salbutamol was exclusively mediated through β(1)-AR and enhanced by non-selective PDE inhibition with theophylline or selective PDE4 inhibition. However, PDE3 did not appear to regulate this effect.

Regulation of gap-junction protein connexin 43 by beta-adrenergic receptor stimulation in rat cardiomyocytes

AIM

beta-adrenergic receptor (beta-AR) agonists are among the most potent factors regulating cardiac electrophysiological properties. Connexin 43 (Cx43), the predominant gap-junction protein in the heart, has an indispensable role in modulating cardiac electric activities by affecting gap-junction function. The present study investigates the effects of short-term stimulation of beta-AR subtypes on Cx43 expression and gap junction intercellular communication (GJIC) function.

METHODS

The level of Cx43 expression in neonatal rat cardiomyocytes (NRCM) was detected by a Western blotting assay. The GJIC function was evaluated by scrape loading/dye transfer assay.

RESULTS

Stimulation of beta-AR by the agonist isoproterenol for 5 min induces the up-regulation of nonphosphorylated Cx43 protein level, but not total Cx43. Selective beta(2)-AR inhibitor ICI 118551, but not beta(1)-AR inhibitor CGP20712, could fully abolish the effect. Moreover, pretreatment with both protein kinase A inhibitor H89 and G(i) protein inhibitor pertussis toxin also inhibited the isoproterenol-induced increase of nonphosphorylated Cx43 expression. Isoproterenol-induced up-regulation of nonphosphorylated Cx43 is accompanied with enhanced GJIC function.

CONCLUSION

Taken together, beta(2)-AR stimulation increases the expression of nonphosphorylated Cx43, thereby enhancing the gating function of gap junctions in cardiac myocytes in both a protein kinase A- and G(i)-dependent manner.Acta Pharmacologica Sinica (2009) 30: 928-934; doi: 10.1038/aps.2009.92.

Risk versus benefit considerations for the beta(2)-agonists

Short-acting beta(2)-agonists are the mainstay of therapy for acute bronchospasm associated with asthma and chronic obstructive pulmonary disease, whereas long-acting beta(2)-agonists are used in maintaining disease control in these respiratory disorders. This review describes and compares the pharmacology of the beta(2)-agonists and explains how these differences translate into differences in efficacy and beta(2)-adrenergic-mediated adverse effects. Questions commonly asked by clinicians regarding the efficacy and safety of short- and long-acting beta(2)-agonists include issues about cardiovascular effects, tolerance to their bronchodilator and bronchoprotective effects, blunting of albuterol response by long-acting beta(2)-agonists, potential masking of worsening asthma control, and the role of long-acting beta(2)-agonists as adjunctive therapy with inhaled corticosteroids in maintaining asthma control. Pharmacogenetics may play a role in determining which patients may be at risk for a reduced response to a beta(2)-agonist. The continued use of racemic albuterol, which contains a mixture of R-albuterol and S-albuterol, has been questioned because of data from preclinical and clinical studies suggesting that S-albuterol causes proinflammatory effects and may increase bronchial hyperreactivity. The preclinical and clinical effects of these two stereoisomers are reviewed. Data describing the efficacy and safety of levalbuterol (R-albuterol) and racemic albuterol are presented.

Inhaled beta2-adrenoceptor agonists: cardiovascular safety in patients with obstructive lung disease

Although large surveys have documented the favourable safety profile of beta(2)-adrenoceptor agonists (beta(2)-agonists) and, above all, that of the long-acting agents, the presence in the literature of reports of adverse cardiovascular events in patients with obstructive airway disease must induce physicians to consider this eventuality. The coexistence of beta(1)- and beta(2)-adrenoceptors in the heart clearly indicates that beta(2)-agonists do have some effect on the heart, even when they are highly selective. It should also be taken into account that the beta(2)-agonists utilised in clinical practice have differing selectivities and potencies. beta(2)-agonist use has, in effect, been associated with an increased risk of myocardial infarction, congestive heart failure, cardiac arrest and sudden cardiac death. Moreover, patients who have either asthma or chronic obstructive pulmonary disease may be at increased risk of cardiovascular complications because these diseases amplify the impact of these agents on the heart and, unfortunately, are a confounding factor when the impact of beta(2)-agonists on the heart is evaluated. Whatever the case may be, this effect is of particular concern for those patients with underlying cardiac conditions. Therefore, beta(2)-agonists must always be used with caution in patients with cardiopathies because these agents may precipitate the concomitant cardiac disease.

Acute electrophysiologic effects of inhaled salbutamol in humans

STUDY OBJECTIVES

Although inhaled beta2-agonists are in widespread use, several reports question their potential arrhythmogenic effects. The purpose of this study was to evaluate the cardiac electrophysiologic effects of a single, regular dose of an inhaled beta2-agonist in humans.

DESIGN

Prospective study.

SETTING

Tertiary referral center.

PATIENTS

Six patients with bronchial asthma and 12 patients with mild COPD.

INTERVENTIONS

All patients underwent an electrophysiologic study before and after the administration of salbutamol solution (5 mg in a single dose).

MEASUREMENTS AND RESULTS

Sinus cycle length, sinus node recovery time (SNRT), interval from the earliest reproducible rapid deflection of the atrial electrogram in the His bundle recording to the onset of the His deflection (AH), interval from the His deflection to the onset of ventricular depolarization (HV), Wenckebach cycle length (WCL), atrial effective refractory period (AERP), and ventricular effective refractory period (VERP) were evaluated just before and 30 min after the scheduled intervention. Salbutamol, a selective beta2-agonist, administered by nebulizer had significant electrophysiologic effects on the atrium, nodes, and ventricle. The AH length decreased from 86.1 +/- 19.5 ms at baseline to 78.8 +/- 18.4 ms (p < 0.001), and the WCL decreased from 354.4 +/- 44.2 to 336.6 +/- 41.7 ms (p = 0.001). Salbutamol significantly decreased the AERP and VERP too while leaving the HV unchanged. Additionally, inhaled salbutamol increased heart rate (from 75.5 +/- 12.8 beats/min at baseline to 93.1 +/- 16 beats/min, p < 0.001) and shortened the SNRT (from 1,073.5 +/- 178.7 to 925.2 +/- 204.9 ms, p = 0.001).

CONCLUSION

Inhaled salbutamol results in significant changes of cardiac electrophysiologic properties. Salbutamol enhances atrioventricular (AV) nodal conduction and decreases AV nodal, atrial, and ventricular refractoriness in addition to its positive chronotropic effects. These alterations could contribute to the generation of spontaneous arrhythmias.

Cardiovascular safety of beta(2)-adrenoceptor agonist use in patients with obstructive airway disease: a systematic review

BACKGROUND

beta(2)-Adrenoceptor agonists have been used as bronchodilators in the management of asthma and chronic obstructive pulmonary disease (COPD); however, there is evidence suggesting that beta(2)-adrenoceptor agonist use may increase morbidity and mortality.

METHODS

A systematic review of case-control studies and randomised controlled trials was performed to evaluate the cardiovascular safety of beta(2)-adrenoceptor agonist use in patients with obstructive airway disease, defined as asthma or COPD.

RESULTS

Case-control studies have shown that beta(2)-adrenoceptor agonist use is associated with an increased risk of myocardial infarction, congestive heart failure, cardiac arrest and sudden cardiac death. The degree of risk appears to be dose-dependent, and may be highest for new users and those with concomitant cardiac conditions. Pooled data from randomised placebo-controlled trials indicate that beta(2)-adrenoceptor agonist use increases the risk of adverse cardiovascular events by more than 2-fold compared with placebo, thus providing evidence that the association seen in case-control studies is a causal one. Single doses of beta(2)-adrenoceptor agonists significantly increase heart rate and decrease potassium concentrations compared with placebo.

CONCLUSIONS

Initiation of beta(2)-adrenoceptor agonist treatment increases heart rate and decreases potassium concentrations, while continued use may increase the risk of adverse cardiovascular events. It could be through these effects of beta-adrenergic stimulation that beta(2)-adrenoceptor agonists may induce ischaemia, congestive heart failure, arrhythmias and sudden cardiac death. In addition to increasing adverse cardiovascular events, beta(2)-adrenoceptor agonist use may induce respiratory tolerance and increase the risk of asthma attacks. It is not clear whether beta(2)-adrenoceptor agonists should be used regularly in the treatment of obstructive airway disease, with or without concomitant cardiovascular disease.

Incidence of out-of-hospital cardiac arrest

Estimates of the incidence of out-of-hospital primary cardiac arrest (CA) have typically relied solely upon emergency medical service or death certificate records and have not investigated incidence in clinical subgroups. Overall and temporal patterns of CA incidence were investigated in clinically defined groups using systematic methods to ascertain CA. Estimates of incidence were derived from a population-based case-control study in a large health plan from 1986 to 1994. Subjects were enrollees aged 50 to 79 years who had had CA (n = 1,275). A stratified random sample of enrollees who had not had CA was used to estimate the population at risk with various clinical characteristics (n = 2,323). Poisson's regression was used to estimate incidence overall and for 3-year time periods (1986 to 1988, 1989 to 1991, and 1992 to 1994). The overall CA incidence was 1.89/1,000 subject-years and varied up to 30-fold across clinical subgroups. For example, incidence was 5.98/1,000 subject-years in subjects with any clinically recognized heart disease compared with 0.82/1,000 subject-years in subjects without heart disease. In subgroups with heart disease, incidence was 13.69/1,000 subject-years in subjects with prior myocardial infarction and 21.87/1,000 subject-years in subjects with heart failure. Risk decreased by 20% from the initial to the final time period, with a greater decrease observed in those with (25%) compared with those without (12%) clinical heart disease. Thus, CA incidence varied considerably across clinical groups. The results provide insights regarding absolute and population-attributable risk in clinically defined subgroups, information that may aid strategies aimed at reducing mortality from CA.

Cardiovascular Effects of β-Agonists in Patients With Asthma and COPD

BACKGROUND

beta-Adrenergic agonists exert physiologic effects that are the opposite of those of beta-blockers. beta-Blockers are known to reduce morbidity and mortality in patients with cardiac disease. beta(2)-Agonist use in patients with obstructive airway disease has been associated with an increased risk for myocardial infarction, congestive heart failure, cardiac arrest, and acute cardiac death.

OBJECTIVES

To assess the cardiovascular safety of beta(2)-agonist use in patients with obstructive airway disease, defined as asthma or COPD.

METHODS

A meta-analysis of randomized placebo-controlled trials of beta(2)-agonist treatment in patients with obstructive airway disease was performed, to evaluate the short-term effect on heart rate and potassium concentrations, and the long-term effect on adverse cardiovascular events. Longer duration trials were included in the analysis if they reported at least one adverse event. Adverse events included sinus and ventricular tachycardia, syncope, atrial fibrillation, congestive heart failure, myocardial infarction, cardiac arrest, or sudden death.

RESULTS

Thirteen single-dose trials and 20 longer duration trials were included in the study. A single dose of beta(2)-agonist increased the heart rate by 9.12 beats/min (95% confidence interval [CI], 5.32 to 12.92) and reduced the potassium concentration by 0.36 mmol/L (95% CI, 0.18 to 0.54), compared to placebo. For trials lasting from 3 days to 1 year, beta(2)-agonist treatment significantly increased the risk for a cardiovascular event (relative risk [RR], 2.54; 95% CI, 1.59 to 4.05) compared to placebo. The RR for sinus tachycardia alone was 3.06 (95% CI, 1.70 to 5.50), and for all other events it was 1.66 (95% CI, 0.76 to 3.6).

CONCLUSION

beta(2)-Agonist use in patients with obstructive airway disease increases the risk for adverse cardiovascular events. The initiation of treatment increases heart rate and reduces potassium concentrations compared to placebo. It could be through these mechanisms, and other effects of beta-adrenergic stimulation, that beta(2)-agonists may precipitate ischemia, congestive heart failure, arrhythmias, and sudden death.