Beta-adrenergic blockade for survivors of acute myocardial infarction

Antihypertensive and cardioprotective effects of three generations of beta-adrenergic blockers: an historical perspective

There are currently, 3 generations of beta-adrenergic blockers for the treatment of hypertension and cardiovascular diseases. The 1^st generation caused vasoconstriction and bronchoconstriction due to β₁ + β₂ receptor blockade and unopposed α₁ receptors. The 2^nd generation of beta-blockers has lesser adverse effects than the 1^st generation with the 3^rd generation beta-blockers having much lesser effects than the other two generations. Current US and International guideline do not recommend beta-blockers as first line therapy of hypertension, but only in the presence of coronary artery disease or heart failure due to their lesser antihypertensive effect. These recommendations are disputed by several older and recent studies which have shown that the beta-blockers are effective and safe for the treatment of hypertension and could be used as first line therapy. To clarify this issue a Medline search of the English language literature was conducted between 2012 and 2021 and 30 pertinent papers were selected. The data from these studies show that the beta-blockers have inferior antihypertensive and stroke protective effect compared with the other classes of antihypertensive drugs and should be used as first line therapy only in patients with hypertension associated with coronary artery disease or heart failure. The information from these papers and collateral literature will be discussed in this perspective.

Beta Adrenergic Blocker Use in Patients With Chronic Obstructive Pulmonary Disease and Concurrent Chronic Heart Failure With a Low Ejection Fraction

Chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) often coexist and present clinicians with diagnostic and therapeutic challenges. Beta-blockers are a cornerstone of CHF treatment, in patients with a low ejection fraction, while beta-agonists are utilized for COPD. These 2 therapies exert opposing pharmacological effects. COPD patients are at an increased risk of mortality from cardiovascular events. In addition to CHF, beta-blockers are used in a number of cardiovascular conditions because of their cardioprotective properties as well as their mortality benefit. However, there is reluctance among physicians to use beta-blockers in patients with COPD because of fear of inducing bronchospasms, despite increasing evidence of their safety and mortality benefits. The majority of this evidence comes from observational studies showing that beta-blockers are safe and well tolerated, with minimal effect on respiratory function. Furthermore, beta-blockers have been shown to lower the mortality risk in patients with COPD alone, as well as in those with COPD and CHF. Large clinical trials are needed in order to dispel the mistrust of beta-blocker use in COPD patients. The current evidence supports the use of cardioselective beta-blockers in patients with COPD. As the population continues to live longer, comorbidities become ever more present, and cardioselective beta-blockers should not be withheld from patients with COPD and coexistent CHF, because the benefits outweigh the risks.

BCL9 provides multi-cellular communication properties in colorectal cancer by interacting with paraspeckle proteins

Colorectal cancer (CRC) is the third most commonly diagnosed cancer, which despite recent advances in treatment, remains incurable due to molecular heterogeneity of tumor cells. The B-cell lymphoma 9 (BCL9) oncogene functions as a transcriptional co-activator of the Wnt/β-catenin pathway, which plays critical roles in CRC pathogenesis. Here we have identified a β-catenin-independent function of BCL9 in a poor-prognosis subtype of CRC tumors characterized by expression of stromal and neural associated genes. In response to spontaneous calcium transients or cellular stress, BCL9 is recruited adjacent to the interchromosomal regions, where it stabilizes the mRNA of calcium signaling and neural associated genes by interacting with paraspeckle proteins. BCL9 subsequently promotes tumor progression and remodeling of the tumor microenvironment (TME) by sustaining the calcium transients and neurotransmitter-dependent communication among CRC cells. These data provide additional insights into the role of BCL9 in tumor pathogenesis and point towards additional avenues for therapeutic intervention.

Implementation of a Nationwide Strategy for the Prevention, Treatment, and Rehabilitation of Cardiovascular Disease "A Todo Corazón"

The cardiovascular diseases (CVDs) have a growing impact over the world mortality, affecting mostly low and middle-income countries. This is due to changes in the population pyramid and the increase in unhealthy lifestyles that predispose the global population to cardiovascular risk factors such as overweight, obesity, smoking, hypertension, diabetes, dyslipidemias and metabolic syndrome. Ischemic heart disease and the cerebral vascular event remain the first causes of death reported by the World Health Organization (WHO) for more than a decade. Mexico has high prevalence in obesity, overweight, hypertension and diabetes in the population over 20 years old; Within the OECD countries (Organization for Economic Cooperation and Development) are the country with the highest mortality due to acute myocardial infarction over 45 years in the first 30 days. In order to face the growing pandemic of CVDs, the IMSS, it has developed and implemented a comprehensive care program called "A Todo Corazon", it is the first program of integral care which seeks to strengthen the actions to improving the impact of CVDs from health. This review is focused on describing the 7 axes that make up the program; each axe is described in detail. Axes one to three are dedicated to promotion and primary prevention of CVDs. Axes 4 and 5 are dedicated to infarction code, as a national strategy to confront the principal cause of death in Mexico. Finally axes 6 and 7 are dedicated to intensive care, secondary prevention and rehabilitation of CVDs.

Beta-Adrenergic Receptor Blockers in Hypertension: Alive and Well

Beta-adrenergic receptor blockers (β-blockers) are an appropriate treatment for patients having systemic hypertension (HTN) who have concomitant ischemic heart disease (IHD), heart failure, obstructive cardiomyopathy, aortic dissection or certain cardiac arrhythmias. β-Blockers can be used in combination with other antiHTN drugs to achieve maximal blood pressure control. Labetalol can be used in HTN emergencies and urgencies. β-Blockers may be useful in HTN patients having a hyperkinetic circulation (palpitations, tachycardia, HTN, and anxiety), migraine headache, and essential tremor. β-Blockers are highly heterogeneous with respect to various pharmacologic properties: degree of intrinsic sympathomimetic activity, membrane stabilizing activity, β₁ selectivity, α₁-adrenergic blocking effects, tissue solubility, routes of systemic elimination, potencies and duration of action, and specific properties may be important in the selection of a drug for clinical use. β-Blocker usage to reduce perioperative myocardial ischemia and cardiovascular (CV) complications may not benefit as many patients as was once hoped, and may actually cause harm in some individuals. Currently the best evidence supports perioperative β-blocker use in two patient groups: patients undergoing vascular surgery with known IHD or multiple risk factors for it, and for those patients already receiving β-blockers for known CV conditions.

Chronic β1-adrenoceptor blockade impairs ischaemic tolerance and preconditioning in murine myocardium

β-adrenoceptor antagonists are commonly used in ischaemic heart disease (IHD) patients, yet may impair signalling and efficacy of 'cardioprotective' interventions. We assessed effects of chronic β1-adrenoceptor antagonism on myocardial resistance to ischaemia-reperfusion (IR) injury and the ability of cardioprotective interventions [classic ischaemic preconditioning (IPC); novel sustained ligand-activated preconditioning (SLP)] to reduce IR injury in murine hearts. Young male C57Bl/6 mice were untreated or received atenolol (0.5g/l in drinking water) for 4 weeks. Subsequently, two cardioprotective stimuli were evaluated: morphine pellets implanted (to induce SLP, controls received placebo) 5 days prior to Langendorff heart perfusion, and IPC in perfused hearts (3×1.5min ischaemia/2min reperfusion). Atenolol significantly reduced in vivo heart rate. Untreated control hearts exhibited substantial left ventricular dysfunction (~50% pressure development recovery, ~20mmHg diastolic pressure rise) with significant release of lactate dehydrogenase (LDH, tissue injury indicator) after 25min ischaemia/45min reperfusion. Contractile dysfunction and elevated LDH were reduced >50% with IPC and SLP. While atenolol treatment did not modify baseline contractile function, post-ischaemic function was significantly depressed compared to untreated hearts. Atenolol pre-treatment abolished beneficial effects of IPC, whereas SLP protection was preserved. These data indicate that chronic β1-adrenoceptor blockade can exert negative effects on functional IR tolerance and negate conventional IPC (implicating β1-adrenoceptors in IR injury and IPC signalling). However, novel morphine-induced SLP is resistant to inhibition by β1-adrenoceptor antagonism.

β-Adrenergic blockade in cardiovascular disease

The development and subsequent clinical application of the β-adrenergic receptor blocking drugs represent one of the major advances in human pharmacotherapeutics. No other class of synthetic drugs has demonstrated such widespread therapeutic utility for the treatment and prevention of so many cardiovascular diseases. In addition, these drugs have proven to be molecular probes that have contributed to our understanding of the disease, and on the molecular level, both the structure and function of the 7 transmembrane G protein receptors that mediate the actions of many different hormones, neurotransmitters, and drugs. The evolution of β-blocker drug development has led to refinements in their pharmacodynamic actions that include agents with relative β1-selectivity, partial agonist activity, concomitant α-adrenergic blockers activity, and direct vasodilator activity. In addition, long-acting and ultra-short-acting formulations of β-blockers have also demonstrated a remarkable record of clinical safety in patients of all ages.

Pharmacology of antiarrhythmic drugs in elderly patients

Bradyarrhythmias and tachyarrhythmias are common in elderly patients as a result of aging and acquired cardiac disease. Antiarrhythmic drugs are effective in elderly patients for the management of supraventricular and ventricular arrhythmias; however, dosing of drugs must be performed with care because of age-related changes in drug pharmacokinetics, the presence of concomitant disease, and frequent drug-drug interactions. Despite the large number of antiarrhythmic drugs having different electrophysiologic actions, as described in this article, only the β-blockers have been shown to be effective in reducing mortality and to lack proarrhythmic actions.

Change in mRNA Expression after Atenolol, a Beta-adrenergic Receptor Antagonist and Association with Pharmacological Response

AIMS: Genetic determinants of variability in response to beta-blockers are poorly characterized. We defined changes in mRNA expression after a beta-blocker to identify novel genes that could affect response and correlated these with inhibition of exercise-induced tachycardia, a measure of beta-blocker sensitivity. METHODS: Nine subjects exercised before and after a single oral dose of 25mg atenolol and mRNA gene expression was measured using an Affymetrix GeneChip Human Gene 1.0 ST Array. The area under the heart rate-exercise intensity curve (AUC) was calculated for each subject; the difference between post- and pre-atenolol AUCs (Delta AUC), a measure of beta-blocker response, was correlated with the fold-change in mRNA expression of the genes that changed more than 1.3-fold. RESULTS: Fifty genes showed more than 1.3-fold increase in expression; 9 of these reached statistical significance (P < 0.05). Thirty-six genes had more than 1.3-fold decrease in expression after atenolol; 6 of these reached statistical significance (P < 0.05). Change in mRNA expression of FGFBP2 and Probeset ID 8118979 was significantly correlated with atenolol response (P = 0.03 and 0.02, respectively). CONCLUSION: The expression of several genes not previously identified as part of the adrenergic signaling pathway changed in response to a single oral dose of atenolol. Variation in these genes could contribute to unexplained differences in response to beta-blockers.

Parasympathetic effects on cardiac electrophysiology during exercise and recovery in patients with left ventricular dysfunction

Depressed parasympathetic activity has been proposed to be associated with an increased risk of sudden death. Parasympathetic effects (PE) on cardiac electrophysiology during exercise and recovery have not been studied in patients with left ventricular dysfunction. We performed noninvasive electrophysiological studies (NI-EPS) and characterized the electrophysiological properties of the sinus node, atrioventricular (AV) node, and ventricle in subjects with depressed left ventricular ejection fraction and dual-chamber defibrillators. NI-EPS were performed during rest, exercise, and recovery at baseline and after parasympathetic blockade with atropine to assess PE (the difference between parameter values in the 2 conditions). Ten subjects (9 men: age, 60 +/- 9 yr; and left ventricular ejection fraction, 29 +/- 8%) completed the study. All NI-EPS parameters decreased during exercise and trended toward rest values during recovery. PE at rest, during exercise, and during recovery, respectively, were on sinus cycle length, 320 +/- 71 (P = 0.0001), 105 +/- 60 (P = 0.0003), and 155 +/- 82 ms (P = 0.0002); on AV block cycle length, 137 +/- 136 (P = 0.09), 37 +/- 19 (P = 0.002), and 61 +/- 39 ms (P = 0.006); on AV interval, 58 +/- 32 (P = 0.035), 22 +/- 13 (P = 0.002), and 36 +/- 20 ms (P = 0.001); on ventricular effective refractory period, 15.8 +/- 11.3 (P = 0.02), 4.7 +/- 15.2 (P = 0.38), and 6.8 +/- 15.5 ms (P = 0.20); and on QT interval, 13 +/- 12 (P = 0.13), 3 +/- 17 (P = 0.6), and 20 +/- 23 (P = 0.04). In conclusion, we describe for the first time the changes in cardiac electrophysiology and PE during rest, exercise, and recovery in subjects with left ventricular dysfunction. PEs are preserved in these patients. Thus the role of autonomic changes in the pathophysiology of sudden death requires further exploration.

Effects on mortality during five years after early intervention with metoprolol in suspected acute myocardial infarction

This study reports the mortality over a 5-year-period determined a double-blind trial, which evaluated the effect of early intervention with metoprolol in suspected acute myocardial infarction. In all, there were 1,395 randomized patients, 698 and 697 of whom were allocated to metoprolol 200 mg daily and placebo treatments, respectively, for the first 3 months. Thereafter, the two groups were treated in a similar fashion implying beta-blockade to a majority. Within the first 3 months, mortality in the metoprolol group was 5.7% versus 8.9% of the placebo group (p = 0.02). This difference persisted after 2 years (metoprolol 13.2%; placebo 17.2%; p = 0.04). Over a 5-year-period, 24.2% of the patients who originally were allocated to metoprolol had died as compared to 25.7% of those originally allocated to placebo (p greater than 0.2). Among patients in whom treatment started early (less than or equal to 8 hours after onset of pain = the median delay time), enzyme activities in the metoprolol group was lower (p = 0.03) than in the placebo group. Mortality during the first 2 years among these patients treated early was lower in the metoprolol (11.8%) than in the placebo group (17.3%; p = 0.04). Corresponding figures after 5 years were 22.0% and 25.3%, respectively (p greater than 0.2). Among patients in whom treatment started later than 8 hours onset of pain, there was neither any difference in enzyme activity nor in mortality after 2 and 5 years. It can be concluded that early treatment with metoprolol in suspected acute myocardial infarction reduced mortality during the first 3 months compared with placebo. The difference persisted after 2 years. However, 5 years after randomization, no significant difference in mortality was observed between the two treatment groups.

Cardio-selective and non-selective beta-blockers in chronic obstructive pulmonary disease: effects on bronchodilator response and exercise

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) often have co-existing cardiovascular disease and may require beta-blocker treatment. There are limited data on the effects of beta-blockers on the response to inhaled beta2-agonists and exercise capacity in patients with COPD.

OBJECTIVE

To determine the effects of different doses of cardio-selective and non-selective beta-blockers on the acute bronchodilator response to beta-agonists in COPD, and to assess their effects on exercise capacity.

METHODS

A double-blind, randomized, three-way cross-over (metoprolol 95 mg, propranolol 80 mg, placebo) study with a final open-label high-dose arm (metoprolol 190 mg). After 1 week of each treatment, the bronchodilator response to salbutamol was measured after first inducing bronchoconstriction using methacholine. Exercise capacity was assessed using the incremental shuttle walk test.

RESULTS

Eleven patients with moderate COPD were recruited. Treatments were well-tolerated although two did not participate in the high-dose metoprolol phase. The area under the salbutamol-response curve was lower after propranolol compared with placebo (P=0.0006). The area under the curve also tended to be lower after high-dose metoprolol (P=0.076). The per cent recovery of the methacholine-induced fall was also lower after high-dose metoprolol (P=0.0018). Low-dose metoprolol did not alter the bronchodilator response. Oxygen saturation at peak exercise was lower with all beta-blocker treatments (P=0.046).

CONCLUSION

Non-selective beta-blockers and high doses of cardio-selective beta-blockers may inhibit the bronchodilator response to beta2-agonists in patients with COPD. Beta-blockers were also associated with lower oxygen saturation during exercise. The clinical significance of these adverse effects is uncertain in view of the benefits of beta-blocker treatment for cardiovascular disease.

Assessment of autonomic function in cardiovascular disease: physiological basis and prognostic implications

Certain abnormalities of autonomic function in the setting of structural cardiovascular disease have been associated with an adverse prognosis. Various markers of autonomic activity have received increased attention as methods for identifying patients at risk for sudden death. Both the sympathetic and the parasympathetic limbs can be characterized by tonic levels of activity, which are modulated by, and respond reflexively to, physiological changes. Heart rate provides an index of the net effects of autonomic tone on the sinus node, and carries prognostic significance. Heart rate variability, though related to heart rate, assesses modulation of autonomic control of heart rate and carries additional prognostic information, which in some cases is more powerful than heart rate alone. Heart rate recovery after exercise represents the changes in autonomic tone that occur immediately after cessation of exercise. This index has also been shown to have prognostic significance. Autonomic evaluation during exercise and recovery may be important prognostically, because these are high-risk periods for sudden death, and the autonomic changes that occur with exercise could modulate this high risk. These markers provide related, but not redundant information about different aspects of autonomic effects on the sinus node.

Post-myocardial infarction beta-blocker therapy: the bradycardia conundrum. Rationale and design for the Pacemaker & beta-blocker therapy post-MI (PACE-MI) trial

Multiple clinical trials have demonstrated beta-blockers improving survival after myocardial infarction (MI). Patients with "bradycardia-related" contraindications to beta-blockers, such as those with asymptomatic bradycardia or AV conduction abnormalities, have been excluded from clinical trials of beta-blockers and continue to be excluded from post-MI beta-blocker therapy in routine clinical practice. These patients tend to be elderly and have a high 1-year mortality. If beta-blockers provide benefit to the post-MI patient independent of their heart rate-lowering effect, then these patients could benefit substantially from initiation of beta-blocker therapy. However, in this particular group of patients, beta-blockers can be safely initiated only if more severe or significant bradycardia can be prevented by pacemaker implantation. It is unclear whether adverse effects related to pacemaker implantation could also negate some or all of the hypothesized benefit of beta-blocker therapy. Although beta-blockers are particularly effective in the elderly, the benefit of beta-blocker therapy in patients with bradycardia-related contraindications to beta-blockers has not been established. The PACE-MI trial is a randomized controlled trial that will address whether beta-blocker therapy enabled by pacemaker implantation is superior to no beta-blocker and no pacemaker therapy after MI in patients with rhythm contraindications to beta-blockers or in those who have developed symptomatic bradycardia due to beta-blockers. The trial will randomize 1124 patients to standard therapy (not to include beta-blockers as patients must have a contraindication to be enrolled) or standard therapy plus pacemaker implantation and beta-blocker. The primary end point is the composite end point of total mortality plus nonfatal reinfarction.

Robustness testing of a chiral NACE method for R-timolol determination in S-timolol maleate and uncertainty assessment from quantitative data

A robustness test of a capillary electrophoresis method for the chiral separation of timolol in nonaqueous acidified media was performed. A two-level Plackett-Burman design was applied in which one qualitative and six quantitative factors were examined. Resolution, migration times and relative migration times to pyridoxine (selected as internal standard) were examined as qualitative responses to evaluate electrophoretic performance. A quantitative response, the content of R-timolol in S-timolol maleate sample, was also considered. Even though some significant factor effects were observed on the qualitative responses, it was still possible to quantify the R-timolol in the S-timolol maleate samples properly. The quantitative response was not significantly affected by the selected factors, demonstrating the robustness of the procedure. However, the use of different HDMS-beta-CD batches seemed to affect both types of responses necessitating to introduce a warning in the procedure. Since the experiments of the Plackett-Burman design can be assimilated to laboratories in an interlaboratory study, uncertainty can be evaluated using the robustness test data. The robustness test was set-up in such a way that the required variances could be estimated.

Interlaboratory study of a NACE method for the determination ofR-timolol content inS-timolol maleate: Assessment of uncertainty

Analyses of statistical variance were applied to evaluate the precision and practicality of a CD-based NACE assay for R-timolol after enantiomeric separation of R- and S-timolol. Data were collected in an interlaboratory study by 11 participating laboratories located in Europe and North America. General qualitative method performance was examined using suitability descriptors (i.e. resolution, selectivity, migration times and S/N), while precision was determined by quantification of variances in the determination of R-timolol at four different impurity levels in S-timolol maleate samples. The interlaboratory trials were designed in accordance with the ISO guideline 5725-2. This allowed estimating for each sample, the different variances, i.e. between-laboratory (s2(Laboratories)), between-day (s2(Days)) and between-replicate (s2(Replicates)). The variances of repeatability (s2r) and reproducibility (s2R) were then calculated. The estimated uncertainty, derived from the precision estimates, seems to be concentration-dependent above a given threshold. This example of R-timolol illustrates how a laboratory can evaluate uncertainty in general.

Cardioselective beta-blockers for chronic obstructive pulmonary disease

BACKGROUND

Beta-blocker therapy has a proven mortality benefit in patients with hypertension, heart failure and coronary artery disease, as well as during the perioperative period. These drugs have traditionally been considered contraindicated in patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To assess the effect of cardioselective beta-blockers on respiratory function of patients with COPD.

SEARCH STRATEGY

A comprehensive search of the Cochrane Airways Group Specialised Register (derived from systematic searches of CENTRAL, MEDLINE, EMBASE and CINAHL) was carried out to identify randomised blinded controlled trials from 1966 to May 2005. We did not exclude trials on the basis of language.

SELECTION CRITERIA

Randomised, blinded, controlled trials of single dose or longer duration that studied the effects of cardioselective beta-blockers on the forced expiratory volume in 1 second (FEV1) or symptoms in patients with COPD.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted data from the selected articles, reconciling differences by consensus. Two interventions studied were the administration of beta-blocker, given either as a single dose or for longer duration, and the use of beta2-agonist given after the study drug.

MAIN RESULTS

Eleven studies of single-dose treatment and 9 of treatment for longer durations, ranging from 2 days to 12 weeks, met selection criteria. Cardioselective beta-blockers, given as a single dose or for longer duration, produced no change in FEV1 or respiratory symptoms compared to placebo, and did not affect the FEV1 treatment response to beta2-agonists. A subgroup analysis revealed no change in results for those participants with severe chronic airways obstruction or for those with a reversible obstructive component.

AUTHORS' CONCLUSIONS

Cardioselective beta-blockers, given to patients with COPD in the identified studies did not produce adverse respiratory effects. Given their demonstrated benefit in conditions such as heart failure, coronary artery disease and hypertension, cardioselective beta-blockers should not be routinely withheld from patients with COPD.

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

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.

Transregulation of the alpha2-adrenergic signal transduction pathway by chronic beta-blockade: a novel mechanism for decreased platelet aggregation in patients

Platelets play a pivotal role in the pathophysiology of acute coronary syndromes. Chronic beta-blockade has been shown to improve the long-term clinical outcome in coronary heart disease. Because platelets play a central role in thrombus formation, the aim of the present study was to investigate if chronic beta-blockade may transregulate the expression of alpha2-adrenergic receptors on human platelets and via this mechanism may modulate platelet activation. The densities of alpha2-adrenergic receptors of platelets were determined in healthy volunteers under chronic beta-blockade and as alpha2-adrenergic receptor-mediated function in catecholamine-induced platelet aggregation was determined. Chronic beta-blockade induced a time-dependent reduction of alpha2-adrenergic receptors. This reduction was accompanied by a decrease of the alpha-subunit of Gi proteins as demonstrated by Western blot analysis. This transregulation at both the receptor level and the G-protein level resulted in an almost complete loss of the alpha2-adrenergic receptor-mediated inhibition of adenylyl cyclase. The impairment of the alpha2-adrenergic receptor system correlated with a reduction of the catecholamine-induced activation and aggregation of human platelets. The functional transregulation of alpha2-adrenergic receptors by chronic beta-blockade in platelets and the consequent impairment of platelet activation may contribute to the therapeutic success of beta-blocker therapy.

[Selection and pharmacological characterisation of Procoralan, a selective inhibitor of the pacemaker If current]

The screening of a series of benzocycloalkane derivatives led to the selection of Procoralan (ivabradine), the first selective inhibitor of the depolarizing If (funny) current of the sinus node, for the treament of myocardial ischaemia. In vitro, this compound reduces the spontaneous beating rate of isolated right rat atria and the firing rate of the action potential of rabbit sinus node preparations. This effect is explained by a reduction in the diastolic depolarisation slope of the action potential and underlies a selective inhibition of the pacemaker If current. In vivo, it induces a selective reduction in heart rate both at rest and during exercise. It preserves myocardial contractility, atrioventricular conduction and ventricular repolarisation duration. Ivabradine exerts a similar anti-ischaemic activity in exercise-induced myocardial ischaemia in pigs to that of a beta-blocker and, furthermore, it limits to a greater extent ischaemic myocardial contractile dysfunction.

Cardiovascular drug class specificity: β-blockers

Beta-adrenergic blockers are one of the most frequently prescribed cardiovascular drugs. Numerous beta-blockers are available for clinical use. Although these agents differ substantially, it is not clear whether (and which) differences are clinically relevant. Most of the important differences among agents reflect the relative specificity for beta1-, beta2-, and alpha-adrenergic receptors. Selection of a particular agent and target dose is probably best guided by available trial data, even though data are limited. Nonselective agents (with or without alpha-blocking properties) devoid of intrinsic sympathetic activity (ISA) are most appropriate postinfarction. Evidence exists demonstrating a mortality benefit postinfarction for propranolol, timolol, metoprolol, and, in the presence of left ventricular dysfunction, carvedilol. In the setting of heart failure, the selective agents metoprolol and bisoprolol as well as the nonselective agent carvedilol (which possesses alpha-blocking properties) have a demonstrated mortality benefit. Not all tolerated beta-blockers are associated with a survival benefit and it is probably not advisable to extrapolate benefits to all drugs with similar (although probably not identical) properties. Carvedilol may possess advantages over other beta-blockers and a possible survival advantage, suggested by the recent Carvedilol or Metoprolol European Trial (COMET), although these findings are not universally accepted. Ultimately, selection of a specific agent avoids obvious contraindications and uses trial data to guide selection and dose as long as side effects are absent or tolerable.

Use of β-Blockers in Patients with COPD

OBJECTIVE:

To evaluate the safety and cardiovascular benefits of β-blocker therapy in patients with chronic obstructive pulmonary disease (COPD).

DATA SOURCES:

Clinical literature was accessed through MEDLINE (1966–February 2003). Key search terms included chronic obstructive pulmonary disease and adrenergic β-antagonists.

DATA SYNTHESIS:

β-Blockers are often avoided in patients with COPD because of fear of bronchoconstriction, despite the known cardiovascular mortality benefits. A review of studies evaluating the use of β-blockers in COPD was undertaken.

CONCLUSIONS:

The literature supports the safety and mortality benefits of using β-blockers in COPD. Patients with mild to moderate COPD should receive cardioselective β-blocker therapy when a strong indication exists.

Cardioselective beta-blockers for chronic obstructive pulmonary disease: a meta-analysis

Beta-blocker therapy has a mortality benefit in patients with hypertension, heart failure and coronary artery disease, as well as during the perioperative period. These drugs have traditionally been considered contraindicated in patients with chronic obstructive pulmonary disease (COPD). The objective of this study was to assess the effect of cardioselective beta-blockers on respiratory function of patients with COPD. Comprehensive searches were performed of the EMBASE, MEDLINE and CINAHL databases from 1966 to May 2001, and identified articles and related reviews were scanned. Randomised, blinded, controlled trials that studied the effects of cardioselective beta-blockers on the forced expiratory volume in 1 s (FEV1) or symptoms in patients with COPD were included in the analysis. Interventions studied were the administration of beta-blocker, given either as a single dose or for longer duration, and the use of beta2-agonist given after the study drug. Outcomes measured were the change in FEV1 from baseline and the number of patients with respiratory symptoms. Eleven studies of single-dose treatment and 8 of continued treatment were included. Cardioselective beta-blockers produced no significant change in FEV1 or respiratory symptoms compared to placebo, given as a single dose (-2.05% [95% CI, -6.05% to 1.96%]) or for longer duration (-2.55% [CI, -5.94% to 0.84]), and did not significantly affect the FEV1 treatment response to beta2-agonists. Subgroup analyses revealed no significant change in results for those participants with severe chronic airways obstruction or for those with a reversible obstructive component. In conclusion, cardioselective beta-blockers given to patients with COPD do not produce a significant reduction in airway function or increase the incidence of COPD exacerbations. Given their demonstrated benefit in conditions such as heart failure, coronary artery disease and hypertension, cardioselective beta-blockers should be considered for patients with COPD.

Anti-Ischemic Effects of Ivabradine, a Selective Heart Rate-Reducing Agent, in Exercise-Induced Myocardial Ischemia in Pigs

The effects of ivabradine, a novel heart rate-reducing agent that inhibits the cardiac pacemaker current If, were compared with those of the beta-adrenergic blocker propranolol, in a model of exercise-induced regional myocardial ischemia in pigs. Five Yucatan micropigs were chronically instrumented to measure hemodynamics, regional myocardial contractility, and local electrograms, and a fixed stenosis of the left anterior descending coronary artery was induced using a clip. Each animal underwent three experiments on different days, each consisting of two treadmill exercise sessions, 4 hours apart. Ivabradine 5 mg/kg, propranolol 5 mg/kg, or vehicle was administered orally 3 hours before the second exercise session. Exercises before treatment and after vehicle produced reproducible hemodynamic changes and regional myocardial ischemia in the area perfused by the stenosed coronary artery, indicated by ST segment shift and regional contractile dysfunction. Ivabradine and propranolol were equipotent in reducing heart rate at rest and limiting tachycardia during exercise. Ivabradine, unlike propranolol, did not reduce left ventricular contractility at rest or during exercise, and did not increase atrio-ventricular conduction time. Both compounds reduced the exercise-induced ST segment shift in the ischemic region by approximately 80%, but ivabradine preserved systolic shortening to a significantly greater degree than propranolol (P < 0.05).

Pharmacokinetics of propranolol after single and multiple dosing with sustained release propranolol or propranolol CR (innopran XL) , a new chronotherapeutic formulation

Blood pressure rises rapidly upon waking and may be responsible, in part, for the increased incidence of myocardial infarction and stroke during the morning hours. Current formulations and dosing of antihypertensive drugs do not provide maximum coverage during this vulnerable period. This study was performed to demonstrate that propranolol CR (Innopran XL), a novel chronotherapeutic formulation of propranolol designed for nighttime dosing, has appropriate pharmacokinetics to provide maximum cardioprotective effect in the morning. Pharmacokinetics of propranolol CR and sustained-release propranolol after single and multiple doses were determined in normal male volunteers in this open-label, 2-period crossover study. The drugs were dosed in the evening and serial blood samples were taken for determination of propranolol concentration the next 24 to 72 hours. After a single 160-mg dose of propranolol CR administered at 10 pm, absorption was delayed by about 4 hours, after which plasma concentration rose steadily, reaching a peak at about 10:00 am. In contrast, after dosing with sustained release propranolol, plasma levels of propranolol began to rise almost immediately, reaching a plateau between 4:00 am and 10:00 am. During multiple dosing, steady-state trough plasma concentrations were achieved after 2 days with either drug. After the final dose, the plasma profiles of both drugs were similar to those observed in the single-dose study. Bioavailability was similar for both formulations of propranolol. Propranolol CR exhibited appropriate pharmacokinetics for a chronotherapeutic approach to the treatment of hypertension.

Cardioselective beta-blockers for chronic obstructive pulmonary disease

BACKGROUND

Beta-blocker therapy has a proven mortality benefit in patients with hypertension, heart failure and coronary artery disease, as well as during the perioperative period. These drugs have traditionally been considered contraindicated in patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To assess the effect of cardioselective beta-blockers on respiratory function of patients with COPD.

SEARCH STRATEGY

A comprehensive search of EMBASE, MEDLINE and CINAHL was performed using the Cochrane Airways Group registry to identify randomised blinded controlled trials from 1966 to May 2001. The search was completed using the terms: asthma*, bronchial hyperreactivity*, respiratory sounds*, wheez*, obstructive lung disease* or obstructive airway disease*, and adrenergic antagonist*, sympatholytic* or adrenergic receptor block*. We did not exclude trials on the basis of language.

SELECTION CRITERIA

Randomised, blinded, controlled trials of single dose or longer duration that studied the effects of cardioselective beta-blockers on the forced expiratory volume in 1 second (FEV1) or symptoms in patients with COPD.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted data from the selected articles, reconciling differences by consensus. Two interventions studied were the administration of beta-blocker, given either as a single dose or for longer duration, and the use of beta2-agonist given after the study drug.

MAIN RESULTS

Eleven studies of single-dose treatment and 8 of treatment for longer duration, ranging from 2 days to 12 weeks, met selection criteria. Cardioselective beta-blockers produced no statistically significant change in FEV1 or respiratory symptoms compared to placebo, given as a single dose (Weighted Mean Difference -2.05% [95% Confidence interval, -6.05 to 1.96%]) or for longer duration (WMD -2.55% [95% CI, -5.94 to 0.84]), and did not significantly affect the FEV1 treatment response to beta2-agonists. Exacerbations and hospitalizations were recorded in all trials, but none occurred during the periods of study, in either group. A subgroup analysis revealed no significant change in results for those participants with severe chronic airways obstruction or for those with a reversible obstructive component.

REVIEWER'S CONCLUSIONS

The available evidence suggests that cardioselective beta-blockers, given to patients with COPD do not produce a significant short-term reduction in airway function or in the incidence of COPD exacerbations. However, the trials were small and of short duration. Given their demonstrated benefit in conditions such as heart failure, coronary artery disease and hypertension, cardioselective beta-blockers should be considered for patients with COPD, but administered with careful monitoring since data concerning long term administration and their effects during exacerbations are not available.

Treatment of hypertension in type 2 diabetes

Hypertension is one of the most common medical conditions in the United States, affecting 50 million American adults and accounting for one of four physician office visits. It is often undetected and undertreated, creating significant public health consequences. In diabetes, hypertension is an even greater problem, as diabetes has become the most common single cause of end-stage renal disease (ESRD) in the world, and diabetes is increasing in prevalence. The most important factor in slowing the decline of renal function in diabetes is aggressive treatment of hypertension. Recent guidelines have emphasized that the target blood pressure levels for patients with diabetes should be lower than in other hypertensive groups. The best specific approach for the treatment of hypertension in diabetic patients is the subject of much debate. It may be in the end that the specific drug choice has less overall importance than the actual attainment of adequate blood pressure control. In addition, more credence must be placed on the value of treating systolic hypertension than has traditionally been given. Coexisting diabetes and hypertension are a common clinical scenario that can set off a vicious cycle of increasing renal damage, rising blood pressure, and increased cardiovascular morbidity and mortality. Treatment often requires multiple drugs to effectively preserve renal function and prevent complications.

Abnormalities of hemorheological, endothelial, and platelet function in patients with chronic heart failure in sinus rhythm: effects of angiotensin-converting enzyme inhibitor and beta-blocker therapy

BACKGROUND

To investigate the hypothesis that abnormalities of hemorheological (fibrinogen, plasma viscosity), endothelial (von Willebrand factor [vWF]), and platelet (soluble P-selectin) function would exist in patients with chronic heart failure (CHF) who are in sinus rhythm, we conducted a cross-sectional study of 120 patients with stable CHF (median ejection fraction 30%). We also hypothesized that ACE inhibitors and beta-blockers would beneficially affect the measured indices.

METHODS AND RESULTS

In the cross-sectional analysis, plasma viscosity (P=0.001), fibrinogen (P=0.02), vWF (P<0.0001), and soluble P-selectin (P<0.001) levels were elevated in patients with CHF compared with healthy controls. Women demonstrated greater abnormalities of hemorheological indices and vWF than males (all P<0.05). Plasma viscosity (P=0.009) and fibrinogen (P=0.0014) levels were higher in patients with more severe symptoms (New York Heart Association [NYHA] class III-IV), but there was no relationship with left ventricular ejection fraction. When ACE inhibitors were introduced, there was a reduction in fibrinogen (repeated-measures ANOVA, P=0.016) and vWF (P=0.006) levels compared with baseline. There were no significant changes in hemorheological, endothelial, or platelet markers after the introduction of beta-blocker therapy, apart from a rise in mean platelet count (P<0.001).

CONCLUSIONS

Abnormal levels of soluble P-selectin, vWF, and hemorheological indices may contribute to a hypercoagulable state in CHF, especially in female patients and in those with more severe NYHA class. Treatment with ACE inhibitors improved the prothrombotic state in CHF, whereas the addition of beta-blockers did not. These positive effects of ACE inhibitors may offer an explanation for the observed reduction in ischemic events in clinical trials.

Cardioselective beta-blocker use in patients with reversible airway disease

BACKGROUND

Beta-blocker therapy has mortality benefit in patients with hypertension, heart failure and coronary artery disease, as well as during the perioperative period. These drugs have traditionally been considered contraindicated in patients with reversible airway disease.

OBJECTIVES

To assess the effect of cardioselective beta-blockers on respiratory function of patients with reversible airway disease. Reversible airway disease was defined as asthma or chronic obstructive pulmonary disease with a reversible obstructive component.

SEARCH STRATEGY

A comprehensive search of EMBASE, MEDLINE and CINAHL was performed using the Cochrane Airways Group registry to identify randomized blinded placebo-controlled trials from 1966 to February, 2000. The search was completed using the terms: asthma*, bronchial hyperreactivity*, respiratory sounds*, wheez*, obstructive lung disease* or obstructive airway disease*, and adrenergic antagonist*, sympatholytic* or adrenergic receptor block*. We did not exclude trials on the basis of language.

SELECTION CRITERIA

Randomized, blinded, placebo-controlled trials of single dose or longer duration that studied the effects of cardioselective beta-blockers on the forced expiratory volume in 1 second (FEV1), symptoms and use of short-acting inhaled beta-agonists, in patients with reversible airway disease. Reversible airway disease was documented by response to methacholine challenge, by an increase in FEV1 of at least 15% to beta-agonist administration, or the presence of asthma as defined by the American Thoracic Society.

DATA COLLECTION AND ANALYSIS

Two independent reviewers extracted data from the selected articles, reconciling differences by consensus. Cardioselective beta-blockers were divided into 2 groups, those with or without intrinsic sympathomimetic activity (ISA). Two interventions studied were the administration of beta-blocker, given either as a single dose or for longer duration, and the use of beta-agonist given after the study drug.

MAIN RESULTS

Nineteen studies for single-dose treatment and 10 for treatment of longer duration met selection criteria. The patients had mild-moderate airways obstruction. For cardioselective beta-blockers taken as a group, administration of a single dose was associated with a 7.98% (CI, 6.19 to 9.77%) reduction in FEV1, but with a 13.16% (CI, 10.76 to 15.56%) increase in beta-agonist response, as compared to placebo. There was no increase in symptoms. After treatment lasting a few days to a few weeks, there was no decrement in FEV1 compared to placebo and no increase in symptoms or inhaler use. Regular use of cardioselective beta-blockers without ISA produced a 13.13% (CI, 5.97 to 20.30) increase in beta-agonist response compared to placebo, a response not seen with beta-blockers containing ISA (-0.60% [CI, -11.7 to +10.5%]).

REVIEWER'S CONCLUSIONS

Cardioselective beta-blockers, given to patients with mild-moderate reversible airway disease, do not produce clinically significant adverse respiratory effects in the short term. It is not possible to comment on their effects in patient with more severe or less reversible disease, or on their effect on the frequency or severity of acute exacerbations. Given their demonstrated benefit in conditions such as heart failure, coronary artery disease and hypertension, cardioselective beta-blockers should not be withheld from patients with mild-moderate reversible airway disease.

Choosing initial antihypertensive drug therapy for the uncomplicated hypertensive patient

Choosing the initial antihypertensive drug for the uncomplicated hypertensive patient is an important and frequent event for the primary care physician. Patients' first experience with antihypertensive drug therapy will likely affect their long-term perception of hypertension treatment. The choice should be made on the basis of sound scientific data and from the patient's perspective and needs. The drug should be taken once a day, should have proven efficacy in hypertension control and cardiovascular morbidity and mortality reduction, and should have as few side effects as possible. Low-dose thiazide diuretics meet this description, although the need to monitor electrolytes may make them less than ideal. The angiotensin II receptor antagonist class, with side-effects similar to those of placebo in controlled trials, is the most attractive from the patient's perspective, although outcome trial data do not yet exist proving that hypertension treatment with angiotensin II receptor antagonists reduces cardiovascular events. The angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists, with their low side-effect profiles and unique effects on vascular remodeling, are attractive second choices to combine with a diuretic if needed, although low-dose diuretic/Beta blocker combinations have also been shown to lower blood pressure with minimal side effects. At present, ensuring adequate long-term hypertension control is the most important aspect of hypertensive care, and which antihypertensive drug(s) the physician chooses can greatly affect the hypertensive patient's ability to achieve and to maintain long-term blood pressure control. (c)2001 by Le Jacq Communications, Inc.

Therapeutic developments in sudden cardiac death

Sudden cardiac death is characterised by the unexpected death of a patient who has been clinically stable. It is frequently due to the development of ventricular tachyarrhythmias. With appropriate treatment, patients can be appropriately resuscitated. Clinically, it is essential to develop treatment strategies to prevent such an episode, as most patients do not survive out-of-hospital cardiac arrest. beta-Blockers are an effective pharmacological therapy in patients following myocardial infarction and in those with congestive heart failure. They may also be effective in other types of heart disease. Anti-arrhythmic agents are not useful as prophylactic drug therapy for reducing mortality in patients at risk for sudden cardiac death. Amiodarone is a notable exception, which may have some benefit, particularly in some subgroups. The implantable cardioverter-defibrillator has emerged as the most effective therapy for preventing sudden cardiac death in high-risk patients. Further work is required to enhance the characterisation of high-risk patients. Genetic analyses in patients with cardiovascular disorders may also identify new approaches to the prevention of sudden cardiac death.

Current concepts in secondary prevention after acute myocardial infarction

Acute myocardial infarction (MI) is the leading cause of death around the globe. Advances in the field of cardiology have identified several effective treatments that have lead to decrease in mortality from this cause over the past 3 decades. The purpose of this article is to review the existing literature in regards to secondary prevention after acute MI. A search of MEDLINE through August of 1999 was carried out to identify any available publications on secondary prevention after MI. Evidence on the use of both pharmacological and nonpharmacological interventions that was shown to be effective in improving morbidity and mortality was sought. Recommendations for the treatment of patients with acute MI are made based on existing evidence. Betablockers, aspirin and lipid-lowering agents for patients with low density lipoprotein-cholesterol > 130 mg% should be used for all patients following a MI. Angiotensin converting enzyme inhibitors are indicated for patients with congestive heart failure and/or reduced left ventricular ejection fraction and are likely protective in most patients. Calcium channel blockers (Verapamil and Diltiazem) are indicated as second-line therapy for patients who have contraindications or are intolerant to betablockers. The routine prophylactic use of antiarrhythmic drugs to suppress ventricular ectopic beats should be avoided. Recommendations regarding diet, smoking cessation and achievement of ideal body weight should be an integral part of patient management. Referral for outpatient rehabilitation should also be strongly encouraged. Finally, adequate control of blood pressure and diabetes cannot be overemphasized. Adherence to these goals in patients with acute MI will lead to better long-term outcomes and reduction in cardiac death, recurrent MI, stroke, and need for coronary revascularization.

Secondary prevention of myocardial infarction: role of beta-adrenergic blockers and angiotensin-converting enzyme inhibitors

beta-Blockers reduce cardiovascular death and reinfarction in patients with a history of myocardial infarction (MI), and angiotensin-converting enzyme (ACE) inhibitors provide an overall survival benefit in patients with signs or symptoms of left ventricular (LV) dysfunction and a history of acute MI. Despite this, these agents remain underused in clinical practice. Appropriate patient selection in standard clinical practice should be encouraged in order to achieve a mortality rate reduction comparable to that seen in clinical trials. It appears from the findings of recent studies that the greatest benefit from beta-blocker therapy is achieved in patients who are more than 60 years of age and in patients at moderate or high risk for reinfarction and death (eg, patients with LV dysfunction or arrhythmias or both). Patients with class I-IV heart failure treated with ACE inhibitors have fewer recurrent infarctions, a lower incidence of severe congestive heart failure, and a reduced incidence of total cardiovascular death and sudden cardiac death. In addition to the studies completed in patients with MI, there are ongoing studies evaluating whether or not ACE inhibitors can reduce myocardial ischemic events in patients without a prior infarction who have coronary artery disease or hypertension and preserved LV function. There is also growing evidence that concomitant therapy with a beta-blocker and an ACE inhibitor may reduce mortality rates beyond that observed with ACE inhibitors alone in survivors of MI who have LV dysfunction.