Intravenous beta-blockade in coronary heart disease: is cardioselectivity or intrinsic sympathomimetic activity hemodynamically useful?

Beta-Blockers and Their Current Role in Maternal and Neonatal Health: A Narrative Review of the Literature

Beta-blockers are a class of medications that act on beta-adrenergic receptors and are categorized as cardio-selective and non-selective. They are principally used to treat cardiovascular conditions such as hypertension and arrhythmias. Beta-blockers have also been used to treat non-cardiogenic indications in non-pregnant individuals and the pediatric population. In pregnancy, labetalol is the mainstay treatment for hypertension and other cardiovascular indications. However, contraindications to certain sub-types of beta-blockers include bradycardia, heart failure, obstructive lung diseases, and hemodynamic instability. There is conflicting evidence of the adverse effects on fetal and neonatal health due to a scarce safety and efficacy profile, and further studies are necessary to understand the pharmacokinetics of the different classes of beta-blockers in pregnancy and fetal health. Understanding the hemodynamic changes during the stages of pregnancy is important to target a more beneficial therapy for both mother and fetus as well as better neonatal outcomes. Beta-blocker use in the pediatric population is less documented in studies but does have the potential to treat various cardiogenic and non-cardiogenic conditions. Future comprehensive studies would further benefit the direction of beta-blocker treatment during pregnancy in neonates and pediatrics.

Beta-blockers in patients without heart failure after myocardial infarction

BACKGROUND

Cardiovascular disease is the number one cause of death globally. According to the World Health Organization (WHO), 7.4 million people died from ischaemic heart disease in 2012, constituting 15% of all deaths. Beta-blockers are recommended and are often used in patients with heart failure after acute myocardial infarction. However, it is currently unclear whether beta-blockers should be used in patients without heart failure after acute myocardial infarction. Previous meta-analyses on the topic have shown conflicting results. No previous systematic review using Cochrane methods has assessed the effects of beta-blockers in patients without heart failure after acute myocardial infarction.

OBJECTIVES

To assess the benefits and harms of beta-blockers compared with placebo or no treatment in patients without heart failure and with left ventricular ejection fraction (LVEF) greater than 40% in the non-acute phase after myocardial infarction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index - Expanded, BIOSIS Citation Index, the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, European Medicines Agency, Food and Drug Administration, Turning Research Into Practice, Google Scholar, and SciSearch from their inception to February 2021.

SELECTION CRITERIA

We included all randomised clinical trials assessing effects of beta-blockers versus control (placebo or no treatment) in patients without heart failure after myocardial infarction, irrespective of publication type and status, date, and language. We excluded trials randomising participants with diagnosed heart failure at the time of randomisation.

DATA COLLECTION AND ANALYSIS

We followed our published protocol, with a few changes made, and methodological recommendations provided by Cochrane and Jakobsen and colleagues. Two review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse events, and major cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial reinfarction). Our secondary outcomes were quality of life, angina, cardiovascular mortality, and myocardial infarction during follow-up. We assessed all outcomes at maximum follow-up. We systematically assessed risks of bias using seven bias domains and we assessed the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 25 trials randomising a total of 22,423 participants (mean age 56.9 years). All trials and outcomes were at high risk of bias. In all, 24 of 25 trials included a mixed group of participants with ST-elevation myocardial infarction and non-ST myocardial infarction, and no trials provided separate results for each type of infarction. One trial included participants with only ST-elevation myocardial infarction. All trials except one included participants younger than 75 years of age. Methods used to exclude heart failure were various and were likely insufficient. A total of 21 trials used placebo, and four trials used no intervention, as the comparator. All patients received usual care; 24 of 25 trials were from the pre-reperfusion era (published from 1974 to 1999), and only one trial was from the reperfusion era (published in 2018). The certainty of evidence was moderate to low for all outcomes. Our meta-analyses show that beta-blockers compared with placebo or no intervention probably reduce the risks of all-cause mortality (risk ratio (RR) 0.81, 97.5% confidence interval (CI) 0.73 to 0.90; I² = 15%; 22,085 participants, 21 trials; moderate-certainty evidence) and myocardial reinfarction (RR 0.76, 98% CI 0.69 to 0.88; I² = 0%; 19,606 participants, 19 trials; moderate-certainty evidence). Our meta-analyses show that beta-blockers compared with placebo or no intervention may reduce the risks of major cardiovascular events (RR 0.72, 97.5% CI 0.69 to 0.84; 14,994 participants, 15 trials; low-certainty evidence) and cardiovascular mortality (RR 0.73, 98% CI 0.68 to 0.85; I² = 47%; 21,763 participants, 19 trials; low-certainty evidence). Hence, evidence seems to suggest that beta-blockers versus placebo or no treatment may result in a minimum reduction of 10% in RR for risks of all-cause mortality, major cardiovascular events, cardiovascular mortality, and myocardial infarction. However, beta-blockers compared with placebo or no intervention may not affect the risk of angina (RR 1.04, 98% CI 0.93 to 1.13; I² = 0%; 7115 participants, 5 trials; low-certainty evidence). No trials provided data on serious adverse events according to good clinical practice from the International Committee for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH-GCP), nor on quality of life.

AUTHORS' CONCLUSIONS

Beta-blockers probably reduce the risks of all-cause mortality and myocardial reinfarction in patients younger than 75 years of age without heart failure following acute myocardial infarction. Beta-blockers may further reduce the risks of major cardiovascular events and cardiovascular mortality compared with placebo or no intervention in patients younger than 75 years of age without heart failure following acute myocardial infarction. These effects could, however, be driven by patients with unrecognised heart failure. The effects of beta-blockers on serious adverse events, angina, and quality of life are unclear due to sparse data or no data at all. All trials and outcomes were at high risk of bias, and incomplete outcome data bias alone could account for the effect seen when major cardiovascular events, angina, and myocardial infarction are assessed. The evidence in this review is of moderate to low certainty, and the true result may depart substantially from the results presented here. Future trials should particularly focus on patients 75 years of age and older, and on assessment of serious adverse events according to ICH-GCP and quality of life. Newer randomised clinical trials at low risk of bias and at low risk of random errors are needed if the benefits and harms of beta-blockers in contemporary patients without heart failure following acute myocardial infarction are to be assessed properly. Such trials ought to be designed according to the SPIRIT statement and reported according to the CONSORT statement.

Beta-blockers for suspected or diagnosed acute myocardial infarction

BACKGROUND

Cardiovascular disease is the number one cause of death globally. According to the World Health Organization, 7.4 million people died from ischaemic heart diseases in 2012, constituting 15% of all deaths. Acute myocardial infarction is caused by blockage of the blood supplied to the heart muscle. Beta-blockers are often used in patients with acute myocardial infarction. Previous meta-analyses on the topic have shown conflicting results ranging from harms, neutral effects, to benefits. No previous systematic review using Cochrane methodology has assessed the effects of beta-blockers for acute myocardial infarction.

OBJECTIVES

To assess the benefits and harms of beta-blockers compared with placebo or no intervention in people with suspected or diagnosed acute myocardial infarction.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, Science Citation Index Expanded and BIOSIS Citation Index in June 2019. We also searched the WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, Turning Research into Practice, Google Scholar, SciSearch, and the reference lists of included trials and previous reviews in August 2019.

SELECTION CRITERIA

We included all randomised clinical trials assessing the effects of beta-blockers versus placebo or no intervention in people with suspected or diagnosed acute myocardial infarction. Trials were included irrespective of trial design, setting, blinding, publication status, publication year, language, and reporting of our outcomes.

DATA COLLECTION AND ANALYSIS

We followed the Cochrane methodological recommendations. Four review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse events according to the International Conference on Harmonization - Good Clinical Practice (ICH-GCP), and major adverse cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial infarction during follow-up). Our secondary outcomes were quality of life, angina, cardiovascular mortality, and myocardial infarction during follow-up. Our primary time point of interest was less than three months after randomisation. We also assessed the outcomes at maximum follow-up beyond three months. Due to risk of multiplicity, we calculated a 97.5% confidence interval (CI) for the primary outcomes and a 98% CI for the secondary outcomes. We assessed the risks of systematic errors through seven bias domains in accordance to the instructions given in the Cochrane Handbook. The quality of the body of evidence was assessed by GRADE.

MAIN RESULTS

We included 63 trials randomising a total of 85,550 participants (mean age 57.4 years). Only one trial was at low risk of bias. The remaining trials were at high risk of bias. The quality of the evidence according to GRADE ranged from very low to high. Fifty-six trials commenced beta-blockers during the acute phase of acute myocardial infarction and seven trials during the subacute phase. At our primary time point 'less than three months follow-up', meta-analysis showed that beta-blockers versus placebo or no intervention probably reduce the risk of a reinfarction during follow-up (risk ratio (RR) 0.82, 98% confidence interval (CI) 0.73 to 0.91; 67,562 participants; 18 trials; moderate-quality evidence) with an absolute risk reduction of 0.5% and a number needed to treat for an additional beneficial outcome (NNTB) of 196 participants. However, we found little or no effect of beta-blockers when assessing all-cause mortality (RR 0.94, 97.5% CI 0.90 to 1.00; 80,452 participants; 46 trials/47 comparisons; high-quality evidence) with an absolute risk reduction of 0.4% and cardiovascular mortality (RR 0.99, 95% CI 0.91 to 1.08; 45,852 participants; 1 trial; moderate-quality evidence) with an absolute risk reduction of 0.4%. Regarding angina, it is uncertain whether beta-blockers have a beneficial or harmful effect (RR 0.70, 98% CI 0.25 to 1.84; 98 participants; 3 trials; very low-quality evidence) with an absolute risk reduction of 7.1%. None of the trials specifically assessed nor reported serious adverse events according to ICH-GCP. Only two trials specifically assessed major adverse cardiovascular events, however, no major adverse cardiovascular events occurred in either trial. At maximum follow-up beyond three months, meta-analyses showed that beta-blockers versus placebo or no intervention probably reduce the risk of all-cause mortality (RR 0.93, 97.5% CI 0.86 to 0.99; 25,210 participants; 21 trials/22 comparisons; moderate-quality evidence) with an absolute risk reduction of 1.1% and a NNTB of 91 participants, and cardiovascular mortality (RR 0.90, 98% CI 0.83 to 0.98; 22,457 participants; 14 trials/15 comparisons; moderate-quality evidence) with an absolute risk reduction of 1.2% and a NNTB of 83 participants. However, it is uncertain whether beta-blockers have a beneficial or harmful effect when assessing major adverse cardiovascular events (RR 0.81, 97.5% CI 0.40 to 1.66; 475 participants; 4 trials; very low-quality evidence) with an absolute risk reduction of 1.7%; reinfarction (RR 0.89, 98% CI 0.75 to 1.08; 6825 participants; 14 trials; low-quality evidence) with an absolute risk reduction of 0.9%; and angina (RR 0.64, 98% CI 0.18 to 2.0; 844 participants; 2 trials; very low-quality evidence). None of the trials specifically assessed nor reported serious adverse events according to ICH-GCP. None of the trials assessed quality of life. We identified two ongoing randomised clinical trials investigating the effect of early administration of beta-blockers after percutaneous coronary intervention or thrombolysis to patients with an acute myocardial infarction and one ongoing trial investigating the effect of long-term beta-blocker therapy.

AUTHORS' CONCLUSIONS

Our present review indicates that beta-blockers for suspected or diagnosed acute myocardial infarction probably reduce the short-term risk of a reinfarction and the long-term risk of all-cause mortality and cardiovascular mortality. Nevertheless, it is most likely that beta-blockers have little or no effect on the short-term risk of all-cause mortality and cardiovascular mortality. Regarding all remaining outcomes (serious adverse events according to ICH-GCP, major adverse cardiovascular events (composite of cardiovascular mortality and non-fatal myocardial infarction during follow-up), the long-term risk of a reinfarction during follow-up, quality of life, and angina), further information is needed to confirm or reject the clinical effects of beta-blockers on these outcomes for people with or suspected of acute myocardial infarction.

Safety of intravenous metoprolol use in unmonitored wards: a single-centre observational study

BACKGROUND AND AIM

This study aims to examine and quantify the risks associated with the use of intravenous metoprolol on unmonitored wards.

METHOD

This study was a retrospective single-centre observational study from 1 January 2009 to 31 December 2013. The study hospital was a 415-bed, private hospital in Melbourne, Victoria. The study population was all patients who received intravenous metoprolol on an unmonitored ward. The primary outcome measure was the rate of serious adverse events (SAE), defined as a complication of intravenous metoprolol resulting in transfer to a critical-care environment, a medical emergency team call or death.

RESULTS

Six hundred and nine patients received a total of 8260 doses of intravenous metoprolol. Seven cases were identified with a SAE deemed possibly related to beta-blocker use and there was one death. All SAE were hypotension, giving an overall rate of hypotension of 7/609 or 1.1% (95% confidence interval (CI), 0.5 to 2.4%) with a rate per dose delivered of 0.8/1000 doses (95% CI 0.3 to 1.7). The death occurred in a 94-year-old woman with abdominal sepsis. After case file review, consensus opinion deemed this to be unrelated to intravenous metoprolol.

CONCLUSION

The use of intravenous metoprolol on unmonitored wards appears to be safe. The complication rate was low, suggesting that this may be a sensible approach to the management of in-hospital populations at risk of beta-blocker withdrawal.

Perioperative heart-type fatty acid binding protein levels in atrial fibrillation after cardiac surgery

BACKGROUND

Postoperative atrial fibrillation (POAF) is common and associated with poor outcomes. Perioperative ischemia can alter arrhythmic substrate.

OBJECTIVE

To demonstrate an association between perioperative measurements of heart-type fatty acid binding protein (HT-FABP), a sensitive marker of ischemic myocardial injury.

METHODS

Blood samples from 63 inpatients undergoing coronary artery bypass surgery, valve surgery, or both were obtained before and up to 4 days after surgery. Continuous telemetry monitoring was used to detect POAF. Fifty-nine patients had at least 3 HT-FABP measurements. The relationship of enzyme-linked immunosorbent assay-measured HT-FABP with POAF was assessed by using joint logistic regression adjusted for age and surgery type.

RESULTS

Thirty-five patients (55%) developed POAF; these were, on average, older (69.3±10 years vs 60±11 years; P = .0019), with a higher prevalence of heart failure (43% vs 17%; P = .034), chronic obstructive lung disease (26% vs 4%; P = .017), preoperative calcium channel blocker use (29% vs 7%; P = .031), and more likely to undergo combined surgery (21% vs 11%, P = .049). The joint age- and coronary artery bypass surgery-adjusted model revealed that postoperative but not preoperative HT-FABP levels predicted POAF (coefficient 1.9±0.87; P = .03). Longer bypass time, prior infarction, and worse renal function were all associated with higher postoperative HT-FABP.

CONCLUSIONS

A greater rise of HT-FABP is associated with atrial fibrillation after cardiac surgery, suggesting that ischemic myocardial damage is a contributing underlying mechanism. Interventions that decrease perioperative ischemic injury may also decrease the occurrence of POAF.

The possible role of the ancillary properties of beta adrenoceptor antagonists in the management of angina pectoris

Beta adrenoceptor antagonists are effective in the symptomatic management of angina pectoris. This paper examines critically the possible influence of the ancillary properties of beta 1 selectivity, partial agonism and membrane-stabilizing action on the response in anginal patients. The response is categorized according to experimental, pharmacological and clinical endpoints, placing emphasis on the possible errors which may arise from extrapolation from the former to the latter. It is concluded: That selective beta adrenoceptor antagonism confers limited, but tangible advantages over non-selective antagonists in regard to patients with reversible airways obstruction, and also in the metabolic and haemodynamic response to acute hypoglycaemia. Cardioselectivity does not influence the central haemodynamic response to exercise, but lessens adrenaline-mediated hypertensive responses to smoking and hypoglycaemia. Non-selective partial agonists cause less reduction in resting ventricular function, but their effects on cardiac output during exercise are indistinguishable from full antagonists. Membrane stabilizing properties have a marked influence on the tolerability of these agents in terms of unwanted, nonspecific central nervous system symptoms. Unresolved questions relate to the influence of partial agonism on fatigue, metabolic responses, especially blood lipids and glucose, and the possibility of lesser efficacy in angina compared to full antagonists.

Parenteral antiarrhythmics for life-threatening ventricular arrhythmias

The acute management of life-threatening ventricular tachyarrhythmias often includes the use of parenteral antiarrhythmics. There are a number of agents currently available for this purpose. They are used to suppress inducible monomorphic ventricular tachycardia during programmed electrical stimulation, they terminate spontaneous sustained ventricular tachycardia, and prevent ventricular fibrillation in the setting of an acute myocardial infarction. Serious adverse reactions include proarrhythmia, hypotension, severe bradyarrhythmias, and precipitation of congestive heart failure. A comparative evaluation of intravenous antiarrhythmics is difficult due to inherent differences in the choice of agents for study, protocol design, patient population, defined endpoint, and serum drug levels. Likewise, the reported adverse reaction rates vary from 0.4% to 75%. To understand the difficulties in clinical decision-making in this problem area, particularly drug selection, we present here a review of pertinent clinical trials evaluating parenteral drug efficacy and adverse effects.

A placebo controlled comparison of the effects of metoprolol and celiprolol on echo-Doppler measurements of cardiovascular function in normal volunteers

1. This study used a continuous-wave echo-Doppler method (Exerdrop) to investigate the effects of beta-adrenoceptor antagonism and partial agonism on cardiovascular responses at rest and during dynamic exercise. 2. A double-blind, randomised, placebo controlled comparison of metoprolol (50 mg) and celiprolol (200 mg) was undertaken in nine normal volunteers; single oral doses of medication were administered at weekly intervals. Rest and exercise (supine bicycle) haemodynamics were assessed at 0, 2, 4, 6 and 8 h following dosing. 3. Before dosing and after placebo, the aortic flow velocity, acceleration and velocity integral increased progressively during exercise, as did heart rate, blood pressure and cardiac output. 4. Following metoprolol 50 mg, heart rate was significantly reduced without change in systolic or diastolic blood pressure. Echo-Doppler peak acceleration and velocity decreased at rest. On exercise, heart rate and systolic blood pressure fell significantly; the increase in acceleration was significantly blunted compared with placebo (a decrease of 15.2% at rest and 22.9% at 75 watts; P < 0.01 vs placebo). Peak velocity fell significantly by 75 watts exercise. 5. Celiprolol 200 mg at rest significantly increased systolic blood pressure, peak acceleration and velocity. On exercise celiprolol, in contrast to metoprolol, did not reduce peak acceleration or peak velocity; however exercise heart rate and systolic blood pressure were significantly reduced. The difference between celiprolol and metoprolol in respect of peak acceleration persisted over the 8 h of the study. 6. These differences between metoprolol and celiprolol are compatible with the partial agonism of celiprolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactions of a new beta-blocker, celiprolol, with the calcium antagonists, diltiazem and nifedipine, on atrioventricular conduction

The influence of a new beta-blocker, celiprolol, on the direct dromotropic effects of the Ca antagonists, diltiazem and nifedipine, on atrioventricular (AV) conduction was estimated in the canine isolated, blood-perfused AV node preparation. Diltiazem (1-10 micrograms) and nifedipine (0.3-3 micrograms) injected i.a. into the AV node artery dose dependently prolonged the atrio-His (AH) interval (5-39 msec and 7-51 msec) in the AV mode preparation. When celiprolol (1 and 10 mg/kg) was given i.v. in the support dog, the AH interval in the AV node preparation was transiently shortened and then maintained constant as a control. These doses of i.v. celiprolol completely abolished the isoproterenol-induced decrease in the AH interval (28 msec at 0.03 microgram, i.a.) and AV nodal tachycardia. In the presence of celiprolol, the same doses of i.a. diltiazem and nifedipine increased the AH interval by the same amounts (6-43 msec and 8-53 msec) as the control. The incidence of second degree AV conduction block produced by diltiazem (2 in 5 AV node preparations at 10 micrograms) and nifedipine (2 in 6 preparations at 3 micrograms) was not changed by celiprolol. In the second experiments, diltiazem (30-300 micrograms/kg) and nifedipine (3-30 micrograms/kg), given i.v. in an open-chest in situ vagotomized dog, dose dependently increased AV conduction time (AVCT; 2-30 msec and 1-12 msec). Celiprolol 1 and 10 mg/kg i.v., which suppressed the isoproterenol-induced decrease in AVCT (32 msec at 0.3 mu/kg i.v.) and AV nodal tachycardia (4 in 6 in situ hearts), potentiated the prolongation of AVCT by the same doses of diltiazem (11-50 msec) and nifedipine (3-40 msec). The incidence of second degree AV conduction block produced by i.v., diltiazem (1 in 5 in situ hearts at 300 micrograms/kg) and nifedipine (0 in 6 in situ hearts at 30 micrograms/kg) was aggravated (4 in 5 and 3 in 6 in situ hearts) after i.v. celiprolol. These results indicate that although celiprolol does not affect the direct negative dromotropic effects of the Ca antagonists, AV block could easily be produced when celiprolol eliminates tonic adrenergic influences in vivo.

Pathophysiologic and pharmacologic rationales for clinical management of chronic heart failure with beta-blocking agents

An understanding of the important role of neurohormonal compensatory mechanisms in heart failure has been translated into therapeutic options that can improve cardiac function, alter disease progression, and improve survival. Angiotensin-converting enzyme inhibitors are of proven benefit in this regard, and beta-adrenergic receptor antagonists are potentially another such class of agents. By inhibiting the myocardial effects of chronic adrenergic activation, beta blocking agents may improve left ventricular function or delay its deterioration in patients with heart failure. Aside from blocking beta-adrenergic receptors, other ancillary properties inherent in third-generation beta-blocking agents (such as vasodilation) may exert additional favorable effects. Clinical data generated in subjects with heart failure indicate that beta-antagonist therapy exerts its physiologic and clinical effects through neurohormonal antagonism, generally analogous to angiotensin-converting enzyme inhibitors. Virtually all controlled long-term studies show that beta-blocking agents improve cardiac function and hemodynamics in patients with chronic heart failure, but large-scale trials are needed to ascertain a favorable effect on the natural history of heart failure.

Hemodynamic interactions of a new beta blocker, celiprolol, with nifedipine in angina pectoris

The hemodynamic consequences of blockade at both beta-adrenoceptors and slow calcium channels is of therapeutic importance for patients with angina pectoris. The hemodynamic interaction of a new cardioselective beta blocker, celiprolol, and nifedipine was examined in an acute hemodynamic study using three prospectively matched groups with angiographically confirmed coronary artery disease (n = 10/group). Patients were randomly allocated to intravenous celiprolol (8 mg), sublingual nifedipine (20 mg), or their combination. Rest and exercise (supine bicycle) hemodynamics were determined before and following each therapy. At rest, celiprolol did not alter pumping function; nifedipine reduced diastolic blood pressure and systemic vascular resistance index (SVRI), with a small increase in heart rate. Combination therapy reduced systemic arterial pressure and SVRI; heart rate and cardiac stroke volume index increased. During exercise celiprolol tended to reduce heart rate and cardiac index; nifedipine reduced exercise SVR and cardiac stroke work indices. Combination therapy reduced all components of blood pressure; cardiac stroke work and SVR indices fell. These hemodynamic data suggest that beta blockade with celiprolol may result in a slight depression of cardiac pumping during exercise; however, such effects are offset by the vasodilating actions of nifedipine (reflex sympathetic action offsetting cardiodepression). Thus the acute hemodynamic effects of this combination were seemingly safe in these patients; the longer term effects during maintained therapy should be further assessed.

Clinical use of beta-adrenoceptor blockade in systemic hypertension

beta-Blockers are effective in reducing the blood pressure of many patients with systemic hypertension. They differ in terms of the presence or absence of intrinsic sympathomimetic activity, membrane-stabilising activity, beta 1-selectivity, alpha-blocking properties, and relative potency and duration of action. All beta-blockers appear to have blood pressure lowering effects. The choice of which beta-blocker to use in an individual patient is determined by the pharmacodynamic and pharmacokinetic differences between the drugs in conjunction with the patient's other medical condition(s). This review discusses the practical use of beta-blockers and provides rational suggestions for which drug(s) to use in selected patient groups (Black, elderly, postinfarction, diabetes, renal disease, obstructive lung disease, elevated lipid levels, coexisting angina, and left ventricular hypertrophy).

Penbutolol and carteolol: two new beta-adrenergic blockers with partial agonism

Penbutolol and carteolol are two new long acting, nonselective beta-adrenergic blockers which have been approved for the treatment of systemic hypertension. Both drugs have intrinsic sympathomimetic activity (partial agonist activity), however, less than that seen with pindolol. They appear to cause less resting bradycardia than propranolol, have no effect on lipids and lipoproteins, and have favorable side effect profiles.

A pressor effect of noncardioselective beta-blockers in mildly hypertensive patients during acute hospitalization

Pressor effects of noncardioselective beta-blockers have been demonstrated in situations of increased sympathetic activity; however, data are limited and the clinical significance of this finding is in doubt. The present study was performed to supply data about the effect of noncardioselective beta-blockers on the stress of acute hospitalization. Of 2,989 patients acutely admitted to a 50-bed unit of general internal medicine in a 647-bed teaching hospital, 234 had used beta-blockers without intrinsic sympathicomimetic activity (ISA) for at least six weeks because of mild hypertension; 199 were evaluable, 56 using nonselective, 143 using selective beta-blockers. The authors found a marked pressor effect of noncardioselective beta-blockers as compared with selective (mean arterial pressure 125 versus 102 mm Hg, p less than 0.001). In the patients who could continue their outpatient medication this effect could be attributed to an overall increase of total peripheral resistance and disappeared within five days of admission. In the patients admitted because of unstable angina pectoris (nonselective n = 15, selective n = 48) myocardial oxygen demand as estimated by the double product (systolic blood pressure heart rate) was significantly higher in the nonselective group (12.926 versus 9.581 mmHg.beats/min, p less than 0.01). The present study supports the need for more controlled data to determine the ultimate place of noncardioselective beta-blockers in situations of increased sympathetic activity.

Stable angina pectoris: 3. Medical treatment

The therapeutic goals for the patient with angina pectoris are to minimize the frequency and severity of angina and to improve functional capacity at a reasonable cost and with as few side effects as possible. An integrated approach necessitates attention to conditions that might be aggravating angina, such as anemia or hypertension. Alterations in life-style and personal habits, such as cessation of cigarette smoking, are often necessary and should be continually reinforced by the physician. Certain concomitant diseases, such as chronic obstructive pulmonary disease, may influence the selection of drug therapy. Nitrates, beta-adrenergic blockers, and calcium entry blockers are the major classes of drugs that can be used alone or in combination in a program that is designed for the individual patient.

Hemodynamic effects of intravenous and oral sotalol

Beta-adrenergic blocking agents may have negative inotropic effects that are particularly worrisome in patients with depressed cardiac function. Their membrane-stabilizing properties may be a contributing factor. Sotalol is currently thought not to cause significant myocardial depression. Intravenous sotalol administration has minimal effects on resting stroke volume, although heart rate and consequently cardiac output are significantly decreased. Systolic blood pressure decreases, with a minimal change in diastolic or mean pressure. Hemodynamic effects are usually seen within 15 to 20 minutes of administration. Hemodynamic indexes are maintained even in patients with mildly depressed ejection fractions (mean ejection fraction of 43 +/- 15%) after oral sotalol administration. Although heart rate decreases, cardiac index is unchanged because of a significant increase in stroke volume index. The latter results from an increase in preload (secondary to bradycardia) and a decrease in afterload. Sotalol is well tolerated, although occasionally it may cause worsening heart failure. This is seen in patients with markedly depressed left ventricular function and inadequate cardiac reserve characterized by an inability to increase stroke volume and cardiac output with exercise. Long-term (1-year) patient follow-up reveals no significant hemodynamic deterioration from initial values obtained after oral administration.

Hyperkinetic circulatory syndrome in patients with presinusoidal portal hypertension. Effect of propranolol

This study evaluates systemic and splanchnic haemodynamics and the effect of propranolol in 15 patients with presinusoidal portal hypertension (portal vein obstruction, n = 11; schistosomiasis, n = 4). These patients exhibited a hyperkinetic circulatory syndrome characterized by high cardiac index (4.4 +/- 1.61.min-1.m-2, mean +/- S.D.) and by low systemic vascular resistance despite normal liver function and sinusoidal pressure. Hepatic blood flow was decreased in half of the patients with portal vein obstruction. Azygos blood flow, an estimate of superior portal-systemic collateral circulation, was markedly increased in all patients (0.46 +/- 0.19 l/min, upper limit of normal: 0.19 l/min). Therefore, in these patients with normal hepatic venous pressure gradient, azygos blood flow measurement provides an index of splanchnic haemodynamic changes. Propranolol administration (15 mg, i.v.) reduced the hyperkinetic circulatory syndrome, with a significant decrease in heart rate (-17 +/- 6%), cardiac index (-25 +/- 12%) and azygos blood flow (-40 +/- 26%) and a significant increase in systemic vascular resistance (+40 +/- 40%). These results suggest that the hyperkinetic circulatory syndrome observed in these patients, could be related to an increase in beta-adrenergic activity. The decrease in azygos blood flow, after propranolol administration, was significantly correlated (r = 0.94) with the increase in right atrial pressure. This finding suggests that propranolol may act through an increase in portal-systemic collateral venous tone. These haemodynamic results justify, in patients with presinusoidal portal hypertension, clinical trials investigating the beneficial effect of beta-blockers on gastrointestinal bleeding caused by portal hypertension.

Hemodynamic assessment of nicardipine alone and with atenolol in coronary artery disease using a modified echo-Doppler device

We have used a modified noninvasive echo-Doppler cardiac output device, based on the principle of attenuated compensation volume flow, to assess the cardiovascular effects of the slow-calcium antagonist nicardipine in coronary disease. The dose-response effects of 2.5, 5.0 and 10.0 mg intravenous nicardipine were determined in 8 patients with angina. Dose-related decreases were seen in systemic mean arterial pressure (p less than 0.01) after administration of nicardipine. Cardiac pumping indexes were improved, as evident from linear increases in cardiac stroke volume (p less than 0.001), stroke length (p less than 0.01) and time-averaged mean velocity (p less than 0.01). The echo-Doppler device was also used to assess beta-blocking/nicardipine combination therapy in patients with angina. When nicardipine was given after the cardioselective beta blocker atenolol the reduction in heart rate and cardiac output after atenolol was reversed compared with a group that received atenolol followed by placebo. Cardiac performance improved and the 35% reduction in systemic vascular resistance was associated with markedly increased cardiac index (p less than 0.01), augmentation of time-averaged mean velocity (p less than 0.01) and cardiac stroke length (p less than 0.05). These data are consistent with previous invasive studies of nicardipine, either alone or when combined with beta blockade in coronary disease. The data also suggest that nicardipine/beta-blocking combination is safe in patients with coronary heart disease and that the echo-Doppler method of cardiovascular monitoring will prove useful in human pharmacodynamic studies.

Myocardial properties of the new dihydropyridine calcium antagonist isradipine compared to nifedipine with or without additional beta blockade in coronary artery disease

Isradipine is a new dihydropyridine calcium antagonist with myocardial effects significantly different from those of nifedipine, as shown by in vitro and animal experimental data. Isradipine selectively inhibits the sinus node but not the atrioventricular conduction and its negative inotropic action is much less if administered in a dose of comparable peripheral effects. To study these effects in man, 40 patients with coronary artery disease were divided into 2 groups receiving either a continuous 30-minute intravenous infusion of 2 mg of nifedipine or 0.5 mg of isradipine, doses that resulted in a comparable afterload reduction (decrease of systemic vascular resistance: nifedipine -22.1%, isradipine -25%, p less than 0.001). Ten patients in each group received an additional intravenous bolus of 5 mg of propranolol at the end of the calcium antagonist administration to antagonize its induced adrenergic reflex mechanisms. The heart rate significantly increased after nifedipine only (+9.2%, p less than 0.001), experienced no change after isradipine and the nifedipine and propranolol combination and decreased after the combination of isradipine and propranolol (-9.6%, p less than 0.001). This resulted in a significant decrease of the rate pressure product with isradipine (-12.5%, p less than 0.001) but not with nifedipine. As a result of the afterload-induced adrenergic reflex mechanisms, the maximal derivative of the left ventricular pressure increased after isradipine administration (+13.5%, p less than 0.001) and was unchanged after nifedipine, which demonstrates the significantly less negative inotropic properties of isradipine as compared with nifedipine.

Left ventricular function and beta-blockers: does intrinsic sympathomimetic activity have any influence during chronic therapy?

A study comparing the chronic effects of propranolol (n = 21) and pindolol (n = 19) on male patients with stable angina pectoris was performed. Left ventricular function was assessed by serial radionuclide ventriculography. Radionuclide ventriculography was performed at rest and during cold pressor test. Both drugs improved symptoms of angina pectoris by at least one division of the New York Heart Association classification. Cold pressor testing caused increases in heart rate and blood pressure in both groups throughout the study. At rest, pretreatment ejection fraction was similar in both groups. During propranolol treatment this rose sequentially from 49% to 55% at 26 weeks. No change in the resting ejection fraction occurred in those taking pindolol. The difference in response between the groups reached significance at 26 weeks. In those with subnormal left ventricular ejection fraction (less than 50%), resting ejection fraction improved significantly throughout treatment with propranolol rising from a basal value of 39% to 51% at 26 weeks. In comparison, pindolol caused no significant change. There is no apparent advantage to intrinsic sympathomimetic activity in terms of preservation or improvement of left ventricular performance in patients with stable angina pectoris prescribed beta-blockers for extended periods of time.

Hemodynamic and hormonal adaptations to beta-adrenoceptor blockade. A 24-hour study of acebutolol, atenolol, pindolol, and propranolol in hypertensive patients

Comparison of the hemodynamic and hormonal effects of beta-adrenoceptor antagonists with different ancillary properties may help to clarify the antihypertensive mechanism of these drugs. Under strict basal conditions, the effects of acebutolol (400 mg b.i.d.), atenolol (100 mg b.i.d.), pindolol (10 mg b.i.d.), and propranolol (80 mg t.i.d.), were studied for the first 24 hours in 40 hypertensive patients. With pindolol, mean arterial pressure was reduced (p less than 0.05) 1 hour after administration, whereas the cardiac index and the systemic vascular resistance index did not change. With the other three drugs, the fall in mean arterial pressure was delayed 2-3 hours. With these drugs, the fall in mean arterial pressure was preceded by a rise in the resistance index, which compensated for the initial fall in cardiac index. With each drug, the decrements in mean arterial pressure were associated with parallel decrements in the resistance index, and percent changes in mean arterial pressure and the resistance index were always significantly (p less than 0.001) correlated. At the end of the 24-hour period, the four drugs shared an equal antihypertensive effect, which varied 14-17%. This was associated with a return of the cardiac index toward control values by acebutolol, atenolol, and propranolol treatment and a moderately increased cardiac index above pretreatment values (13%, p less than 0.01) with pindolol. The secondary rise in the cardiac index was inversely correlated (p less than 0.001) with the fall in mean arterial pressure with all four drugs. Plasma renin was maximally suppressed 2 hours after treatment, thus before any change in mean arterial pressure had occurred with acebutolol, atenolol, and propranolol. Pretreatment values of active renin and the reduction of mean arterial pressure 24 hours after administration were not correlated in any of the four groups. Despite the "vasodilator" action of the four drugs, plasma norepinephrine did not rise. Our data show that the main hemodynamic change that occurs at the time blood pressure falls after beta-adrenoceptor antagonism is vasodilation. Neither autoregulation of blood flow nor renin suppression can explain this vasodilator action. The absence of an increase in norepinephrine, despite vasodilation, suggests that beta-adrenoceptor antagonism interferes with sympathetic vasoconstrictor nerve activity. This effect may explain the vasodilator and antihypertensive potential of beta-adrenoceptor antagonists.

Comparative haemodynamic effects of betaxolol and propranolol in patients with cirrhosis

The acute effects of betaxolol (10 mg, intravenously), a new cardioselective beta-blocker, and propranolol (15 mg, intravenously) on splanchnic and systemic circulations were studied in two matched groups of six patients with portal hypertension due to cirrhosis. Similar decreases in hepatic venous pressure gradient and azygous blood flow--an estimation of superior portosystemic shunts--were observed after both drugs, whereas hepatic blood flow was not modified. The decreases in heart rate and cardiac index were also similar after betaxolol and propranolol. Both drugs induced a significant decrease in the fraction of cardiac output flowing through superior portosystemic shunts. These findings confirm that the marked effect of beta-adrenoceptor blocking agents on splanchnic circulation results both from the reduction in cardiac output and from a vasoconstriction of the portal vein territory, and demonstrate that this vasoconstriction of the portal vein area does not necessitate a beta 2-blocking activity of the drug. The similar efficiency of the two agents in decreasing the hyperkinetic circulation suggests that betaxolol merits further long-term study in the pharmacologic treatment of portal hypertension.

Systemic and coronary hemodynamic effects of combined oral alpha- and beta-adrenergic blockade (labetalol) in normotensive patients with stable angina pectoris and positive exercise stress tests

The systemic and coronary hemodynamic effects of combined alpha- and beta-adrenergic blockade produced by oral labetalol were assessed in 12 normotensive patients with angina pectoris and an ischemic electrocardiographic response to exercise stress. At rest, labetalol (200 mg, orally) produced systemic vasodilation (systemic vascular resistance -9%, p less than .01) as aortic pressure fell and cardiac output was unchanged. Left ventricular (LV) end-diastolic pressure also fell slightly (17%, p = .05). Systemic vasodilation was not accompanied by reflexly mediated increases in heart rate. Coronary flow and resistance and myocardial oxygen uptake were unchanged. Before labetalol, supine bicycle exercise produced angina in 10 patients. After labetalol, exercise duration was prolonged in 6 of these 10 (average 56%). During exercise, tachycardia was blunted (-7%, p less than .05) as were increases in aortic pressure (-12%, p less than .01) and coronary sinus flow (-25%, p = .03). Cardiac output and LV end-diastolic pressure were similar to control period values. These hemodynamic effects of oral labetalol appeared beneficial, differed from those expected of classic beta-adrenergic blocking agents, and were, in general, similar to those we have observed after intravenous labetalol. The clinical response was good and the drug safe. Labetalol should undergo further evaluation in normotensive as well as hypertensive patients with ischemic heart disease.

Effect of atenolol and pindolol on the phorbol ester-induced coronary vasoconstriction in the isolated perfused heart of the rat

1. The effects of atenolol (beta 1-adrenoceptor antagonist without partial agonistic activity) and pindolol (beta 1- and beta 2-antagonist with partial agonistic activity) were studied on basal coronary vascular tone and on the phorbol ester-induced coronary vasoconstriction in the rat perfused heart. 2. The addition of the phorbol ester 12-0-tetradecanoyl-phorbol-13-acetate (TPA; 1.8 X 10(-8)-1.6 X 10(-7) M) into the perfusion fluid during perfusion of rat heart at constant flow caused a dose-dependent, sustained increase in perfusion pressure. The vasoconstrictor response in hearts of reserpine-treated rats to infusion of TPA was similar to that of non-reserpine treated hearts. 3. Infusion of a calcium channel agonist Bay K 8644 at a concentration of 4 X 10(-7) M enhanced, whereas isoprenaline (1 X 10(-5) M), dibuturyl-cyclic AMP (1.6 X 10(-4) M) and forskolin (1 X 10(-6) M), which elevate intracellular concentrations of cyclic AMP, all inhibited the coronary vasoconstriction induced by TPA. 4. Pindolol, in doses which produced comparable inhibition of isoprenaline-induced tachycardia, dose-dependently attenuated the phorbol ester-induced increase in perfusion pressure, whereas atenolol had no effect. The inhibitory action of pindolol (2 X 10(-5) M) on TPA-induced vasoconstriction was blocked by addition of 2.2 X 10(-5) M propranolol into the perfusion fluid. When infused alone, atenolol (2 X 10(-4) M) significantly increased coronary vascular tone, but pindolol had no effect. 5. The present results indicate that pindolol has coronary vasodilator properties due to stimulation of vascular beta-adrenoceptors. If stenosis dilatation of coronary artery spasm is an important component of the anti-anginal effect of beta-blocking drugs, the possession of partial agonistic property by a beta-blocking drug may be of importance in maintaining coronary flow.

Beta-adrenergic receptor blockers. Adverse effects and drug interactions

Adverse effects of beta-adrenergic receptor blocking drugs can be divided into two categories: 1) those that result from known pharmacological consequences of beta-adrenergic receptor blockade; and 2) other reactions that do not appear to result from beta-adrenergic receptor blockade. Adverse effects of the first type include bronchospasm, heart failure, prolonged hypoglycemia, bradycardia, heart block, intermittent claudication, and Raynaud's phenomenon. Neurological reactions include depression, fatigue, and nightmares. It is not yet proven whether the beta 1-selective adrenergic blockers or those with partial agonist activity reduce the overall frequency of adverse reactions seen with propranolol. Patient age does not appear, in itself, to be associated with more beta-blocker side effects. Side effects of the second category are rare. They include an unusual oculomucocutaneous reaction and the possibility of oncogenesis. There are also many drugs that interact with beta-blockers, which may increase toxicity. Finally, there are specific patient characteristics where one beta-blocker may be more effective and safer than another.

Beta-adrenergic blockers

beta-Adrenergic blocking drugs have been available for several years to treat ischemic heart disease and other cardiovascular and noncardiovascular disorders. There are multiple drugs in this class with various pharmacodynamic and pharmacokinetic properties that may be important in specific clinical situations and in avoiding certain adverse reactions. These drugs have been shown to be efficacious in relieving anginal symptoms and prolonging exercise tolerance, in reducing high blood pressure, for treating various arrhythmias, in therapy of hypertrophic cardiomyopathy, and for prolonging life in many survivors of acute myocardial infarction.

An assessment of the partial agonist activity of Ro 31-1118, flusoxolol and pindolol in man

1. The effects of single oral doses of three beta-adrenoceptor partial agonists (Ro 31-1118, flusoxolol and pindolol), two beta-adrenoceptor antagonists (propranolol and atenolol), two beta-adrenoceptor agonists (salbutamol and prenalterol) and placebo on sleeping heart rate, quality of sleep, supine heart rate, exercise heart rate, blood pressure, forearm blood flow and finger tremor were studied in eight healthy male volunteers. 2. Sleeping heart rate was increased by Ro 31-1118, flusoxolol, pindolol, salbutamol and prenalterol and decreased by propranolol and atenolol. 3. None of the drugs studied affected quality of sleep. 4. Supine heart rate was increased by flusoxolol, prenalterol and salbutamol, unaffected by Ro 31-1118 and pindolol and reduced by propranolol and atenolol. 5. Exercise heart rate was reduced by both beta-adrenoceptor antagonists and the three partial agonists and unaffected by salbutamol and prenalterol. 6. Systolic blood pressure was increased by Ro 31-1118, flusoxolol, salbutamol and prenalterol, unaffected by pindolol and reduced by propranolol and atenolol. Diastolic blood pressure was reduced by salbutamol and prenalterol. 7. Forearm blood flow was increased by Ro 31-1118, salbutamol and prenalterol, unchanged by pindolol and flusoxolol and decreased by atenolol and propranolol. 8. Finger tremor was increased by Ro 31-1118, flusoxolol, pindolol, salbutamol, and prenalterol. 9. beta-adrenoceptor partial agonists have different effects on the cardiovascular system and finger tremor to beta-adrenoceptor antagonists. 10. While Ro 31-1118 and flusoxolol are antagonists mainly at the beta 1-adrenoceptor they have agonist activity at both beta 1- and beta 2 adrenoceptors. 11. While pindolol is a non-selective antagonist its agonist activity is mainly at the beta 2-adrenoceptor.

Comparison of selective (beta 1) and nonselective (beta 1 and beta 2) beta-adrenergic blockade on systemic and coronary hemodynamic findings in angina pectoris

To investigate the influence of selective beta 1-adrenergic blockade, in contrast to beta 1- and beta 2-adrenergic blockade, systemic and coronary hemodynamics were studied. Measurements were made at rest and during exercise in 23 patients with suspected coronary artery disease (CAD) before and after either metoprolol or propranolol, given in doses to provide comparable beta 1-receptor blockade. Quantitative coronary angiography was performed at rest. Using a randomized, double-blind protocol, either beta 1 and beta 2 blockade was produced by propranolol (0.1 mg/kg intravenously), or selective beta 1 blockade was produced by metoprolol (0.15 mg/kg intravenously). As expected, at these doses both drugs produced a comparable decrease in heart rate at rest and during exercise, averaging 9% and 14% after propranolol and 10% and 16% after metoprolol. Exercise duration to ischemia was prolonged in most patients with severe CAD after either propranolol (5 of 7) or metoprolol (6 of 10) treatment. The effects of these 2 beta-blocking drugs on systemic hemodynamic values at rest and during exercise were similar. Additionally, coronary sinus flow was usually unchanged by both drugs at rest (-5% after propranolol and -4% after metoprolol, differences not significant) and decreased a similar amount during exercise (-15% after propranolol and -9% after metoprolol, both p less than 0.05). Coronary resistance did not change significantly with either drug (0% after propranolol and 3% after metoprolol), and during exercise (11% after propranolol and 3% after metoprolol), suggesting that decreases in flow were secondary to reduced demand. Furthermore, neither drug produced detectable changes in coronary artery size.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of beta 1-selectivity and intrinsic sympathomimetic activity in a beta-adrenergic blocking drug

Almost all beta-adrenergic blockers, regardless of their pharmacologic characteristics, appear to have blood pressure-lowering activity in hypertensive patients. Comparisons between nonselective beta-blocking agents, such as propranolol and nadolol, with beta 1-selective drugs, such as metoprolol, atenolol and acebutolol, have demonstrated close similarities in their antihypertensive effects in patients. Similarly, beta blockers with and without intrinsic sympathomimetic activity (ISA) have comparable antihypertensive effects. However, beta-selective agents may offer some advantages over conventional beta blockers in hypertensive patients with concurrent conditions such as chronic obstructive airways disease, peripheral vascular disease, diabetes and hyperlipidemia. Beta 1-selective drugs are also preferred in diabetic patients receiving hypoglycemic agents because they do not interfere with glycogenolysis. Agents lacking ISA, such as propranolol, acutely increase peripheral resistance. beta blockers with ISA usually lower resistance. ISA may also minimize the bradycardia frequently found in elderly patients. Agents with ISA may protect against the decrease in high density lipoprotein cholesterol and the modest increase in triglycerides noted with some beta blockers that do not have ISA. Thus, in a large number of clinical situations in which hypertension is found, the properties of beta 1 selectivity and ISA allow beta blockers to be used with greater safety. Therefore, agents possessing both of these properties may be particularly valuable.

Clinical differences between beta-adrenergic blocking agents: implications for therapeutic substitution

The beta blockers exhibit clinically significant differences in beta-receptor selectivity, intrinsic sympathomimetic activity, and alpha-adrenergic blocking activity. These agents also show important differences in their pharmacokinetic profiles, including gastrointestinal absorption, first-pass hepatic metabolism, lipid solubility, protein binding, hepatic biotransformation, pharmacologic activity of metabolites, and renal clearance of unchanged drug and metabolites. These many differences determine the appropriateness of administering a given beta blocker in a given clinical situation. The selection of beta blockers must also take into account concurrent therapy with other agents. Concurrent administration of beta blockers with drugs that alter gastric, hepatic, or renal function may affect blood levels, duration of action, or efficacy of beta-blocker action. The beta blockers vary in the extent to which their action is altered when they are given with other agents, and therapeutic substitution may produce unwanted side effects and toxicity. Elderly patients should be carefully monitored following interchange among beta blockers, since the probability of drug interaction, impact of adverse effects, unpredictability of response, and physiologic variability of renal and liver function is greater than for younger individuals. Therapeutic substitution among beta blockers in patients already stabilized on a given agent will require careful monitoring. Retitration with the new beta blocker will be required in many cases to assure therapeutic equivalence. Beta blockers are currently used for over 20 medical conditions. There is wide variation in the strength of the clinical evidence supporting the use and efficacy of specific beta blockers for specific conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and coronary hemodynamic effects of combined alpha- and beta-adrenergic blockade (labetalol) in normotensive patients with stable angina pectoris and positive exercise stress test responses

The systemic and coronary hemodynamic effects of combined alpha- and beta-adrenergic blockade produced by labetalol were assessed in 12 normotensive patients with angina pectoris and an ischemic electrocardiographic response to exercise stress. When given to the patient at rest, labetalol (0.5 mg/kg intravenously) produced systemic and coronary vasodilation (mean 16% and 13%, respectively, both p less than 0.05); aortic pressure decreased, cardiac output increased and coronary flow and heart rate did not change. Before labetalol treatment, supine bicycle exercise produced angina in all patients. After treatment, exercise duration was prolonged in 8 patients (average 33%). At the same duration of exercise that led to angina during the control period, ST depression in lead V5 was less after labetalol (from 1.2 to 0.4 mm, p less than 0.5). During exercise, tachycardia was blunted (-12%, p less than 0.05) as were the increases in aortic pressure (-12%, p less than 0.05), left ventricular end-diastolic pressure (-7%, difference not significant) and coronary sinus flow (-16%, p less than 0.05). Cardiac output and systemic and coronary vascular resistance were similar to values during control exercise. The hemodynamic effects of labetalol appeared to be beneficial and differed from those of classic beta-adrenergic blocking agents.

Changes in haemodynamics and left ventricular function during intravenous nifedipine infusion with and without additional propranolol in patients with coronary artery disease. A randomized, placebo controlled trial

The haemodynamic effects of a combined intravenous treatment of nifedipine and propranolol in ten patients with coronary artery disease compared to a single treatment with nifedipine or placebo were investigated. Nifedipine infusion resulted in a reduction of left ventricular (LV) afterload and LV volumes with an increase in heart rate and EF and no change of the double product, coronary sinus flow, LV diastolic parameters and dp/dtmax. Addition of propranolol lowers myocardial oxygen demand by reducing heart rate and dp/dtmax together with a sustained afterload reduction with no change in LV volumes and EF. The vasodilatatory action of nifedipine pretreatment balanced the negative effects of acute beta-receptor blockade on LV function and allows the reduction of myocardial oxygen demand without a deterioration of LV function.

Systemic and renal vasodilation after beta-adrenoceptor blockade with pindolol: a hemodynamic study on the onset and maintenance of its antihypertensive effect

Pindolol, a beta blocker with considerable partial agonist activity (PAA), was studied in 10 hypertensive subjects. The maximal fall in mean arterial pressure (MAP) was seen 3 to 4 hours after oral dosing with 10 mg of pindolol (-15 +/- 3%, mean +/- SEM). This was caused by a reduction in total peripheral resistance (TPR), which amounted to 25 +/- 4% after 24 hours. Cardiac output increased by 16 +/- 5%. Cardiac filling pressures and pulmonary artery pressure did not change. Increasing the dose of pindolol, from 5 mg twice a day to 15 mg twice a day over a 3-week period, caused no further change in MAP. After 3 weeks, the fall in MAP (-11 +/- 2%) was maintained by reduced TPR (-26 +/- 6%), whereas cardiac output and stroke volume were increased by 16 +/- 6% and 26 +/- 6%. Renal blood flow and glomerular filtration rate did not change. Beta blockers devoid of PAA lower cardiac output, whereas the elevated TPR in hypertension is unchanged. The hemodynamic profile of pindolol essentially differs from that of beta blockers devoid of PAA.

Metoprolol. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy, in hypertension, ischaemic heart disease and related cardiovascular disorders

During the intervening years since metoprolol was first reviewed in the Journal (1977), it has become widely used in the treatment of mild to moderate hypertension and angina pectoris. Although much data have accumulated, its precise mechanisms of action in these diseases remain largely uncertain. Optimum treatment of hypertension and angina pectoris with metoprolol is achieved through dose titration within the therapeutic range. It has been clearly demonstrated that metoprolol is at least as effective as other beta-blockers, diuretics and certain calcium antagonists in the majority of patients. Although a twice daily dosage regimen is normally used, satisfactory control can be maintained in many patients with single daily doses of conventional or, more frequently, slow release formulations. Addition of a diuretic may improve the overall response rate in hypertension. Several controlled trials have studied the effects of metoprolol administered during the acute phase and after myocardial infarction. In early intervention trials a reduction in total mortality was achieved in one moderately large trial of prolonged treatment, but in another, which excluded patients already being treated with beta-blockers or certain calcium antagonists and where treatment was only short term, mortality was significantly reduced only in 'high risk' patients. Overall results with metoprolol have not demonstrated that early intervention treatment in all patients produces clinically important improvement in short term mortality. Thus, the use of metoprolol during the early stages of myocardial infarction is controversial, largely because of the requirement to treat all patients to save a small number at 'high risk'. This blanket coverage approach to treatment may be more justified during the post-infarction follow-up phase since it has been shown that metoprolol slightly, but significantly, reduces the mortality rate for periods of up to 3 years. Metoprolol is generally well tolerated and its beta 1-selectivity may facilitate its administration to certain patients (e.g. asthmatics and diabetics) in whom non-selective beta-blockers are contraindicated. Temporary fatigue, dizziness and headache are among the most frequently reported side effects. After a decade of use, metoprolol is well established as a first choice drug in mild to moderate hypertension and stable angina, and is beneficial in post-infarction patients. Further study is needed in less well established areas of treatment such as cardiac arrhythmias, idiopathic dilated cardiomyopathy and hypertensive cardiomegaly.

Differences in haemodynamic response to beta-blocking drugs between stable coronary artery disease and acute myocardial infarction

Theoretically the increased sympathoadrenal activity following acute myocardial infarction might augment the haemodynamic impact of beta-adrenoceptor blockade. To evaluate this question 32 haemodynamic studies were performed to compare the effects of equivalent beta-blocking doses of propranolol (8 mg i.v.) and pindolol (0.8 mg i.v.) in patients with a recent acute myocardial infarction (A.M.I.) or stable coronary artery disease (and a presumptive low sympathetic state). In stable coronary artery disease there were clear differences between the haemodynamic impact of propranolol and pindolol. Propranolol decreased both heart rate (delta HR -7 beat/min) and cardiac index (delta CI -0.4 l/min/m2), with an increased pulmonary artery occluded pressure (delta PAOP +4 mmHg) and systemic vascular resistance index (delta SVRI +358 dyn X s X cm-5 m2). However an equivalent beta-blocking dose of pindolol increased PAOP (delta PAOP +3 mmHg) leaving other variables unchanged. These differential actions of propranolol and pindolol have previously been ascribed to the intrinsic sympathomimetic activity (I.S.A.) of pindolol maintaining cardiac pumping function in a low sympathetic state. In contrast following myocardial infarction, both drugs reduced cardiac index to a significantly greater extent compared with stable coronary artery disease (delta CI propranolol -0.81/min/m2; pindolol -0.4 l/min/m2; p less than 0.05); propranolol also reduced the systemic arterial blood pressure (delta systolic -10 mmHg; delta mean -5 mmHg; p less than 0.05). The haemodynamic relevance of the I.S.A. of pindolol appeared attenuated following A.M.I. These data are compatible with experimental evidence of sympathetic nervous activation following coronary occlusion; the resulting hyperadrenergic state appears to condition an augmented haemodynamic response to beta-blocking drugs irrespective of their ancillary pharmacological properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of an ultra short-acting beta-blocker in patients with acute myocardial ischemia

Esmolol is a new ultra short-acting (half-life [t1/2] beta 9 min) beta 1-adrenergic-receptor antagonist reported to have no intrinsic sympathomimetic activity. The safety and efficacy of esmolol in lowering the ventricular rate and rate-pressure product in patients with acute myocardial infarction (n = 5), postmyocardial infarction angina (n = 10), or acute unstable angina (n = 4), and without cardiogenic shock were studied. After a 30 min observation period, esmolol was titrated to a maximum dose of 300 micrograms/kg/min and infused for up to 420 min. The ventricular rate fell from 92 +/- 11 (mean +/- SD) to 77 +/- 13 beats/min (p less than .01) and the systolic arterial pressure decreased from 120 +/- 13 to 97 +/- 11 mm Hg (p less than .01) during the initial 30 min titration period. There was no significant change during the maintenance phase, and both the ventricular rate and arterial pressure returned rapidly toward baseline values within 30 min of termination of the infusion. The cardiac index fell from 2.8 +/- 0.6 to 2.2 +/- 0.6 liters/min/m2 (p less than .01) during the same period, and also returned to the baseline level 30 min after termination of the infusion. There was no significant change in the pulmonary capillary wedge pressure, respiratory rate, or PR interval. Five patients required termination of infusion because of hypotension and all recovered uneventfully within 30 min of stopping the esmolol. One patient required a brief infusion of dopamine to restore hemodynamic stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection of optimal drug therapy for the patient with angina pectoris

The development of new drugs, especially beta-blocking and calcium entry-blocking agents, has greatly facilitated the medical treatment of angina pectoris. The specific needs of each patient should dictate the appropriate treatment of angina pectoris. Angina may occur in patients who have various concomitant disorders such as hypertension, diabetes mellitus, peripheral vascular disease, chronic obstructive pulmonary disease, or arrhythmias, and the physician must take these factors into account when a drug regimen is prescribed. Individual drugs should be chosen on the basis of specifically desired pharmacologic effects, and the dosages should be gradually adjusted according to the patient's response. Although a therapeutic regimen should be selected primarily on the basis of efficacy, the physician must also attempt to recommend a simple and cost-effective program.

Acute hemodynamic and electrophysiologic effects of propranolol in patients receiving diltiazem

Because the combined use of a beta-adrenergic blocking agent and a calcium antagonist may be beneficial in some patients with severe angina, the acute hemodynamic and electrophysiologic effects of intravenous propranolol in the presence and absence of oral diltiazem treatment was studied. In 22 patients (11 men, 11 women, mean age 50 years), 12 receiving diltiazem (mean 243 mg/day, range 180 to 360) and 10 not receiving diltiazem, hemodynamic and electrophysiologic variables were measured before and 5 minutes after intravenous propranolol (0.1 mg/kg). Cardiac index (by thermodilution) and left ventricular (LV) peak dP/dt fell and LV end-diastolic pressure increased similarly in both groups. Mean systemic arterial pressure was unchanged. Coronary sinus blood flow (by thermodilution) decreased slightly in patients receiving diltiazem and was unchanged in those not receiving it. Propranolol caused a similar reduction in heart rate and increase in atrio-His conduction in both groups. Thus, when intravenous propranolol is given to patients with normal or only mildly depressed LV systolic function, the hemodynamic and electrophysiologic effects are similar in those receiving and not receiving oral diltiazem.

The effects on left ventricular performance of verapamil and metoprolol singly and together in exercise-induced angina pectoris

Concurrent therapy with the calcium channel blocker, verapamil, and the beta-blocking group of compounds is usually felt to be clinically contraindicated due to the former's potent dromotropic and negative inotropic actions. The basis of this assumption was examined in a rest and exercise hemodynamic study of the effects of verapamil and the cardioselective beta-blocking drug, metoprolol, in 22 patients with stable angina pectoris and angiographically confirmed coronary artery disease. In a randomized study, 11 patients were assessed following intravenous verapamil (16 mg) alone, 11 following intravenous metoprolol (10 mg) alone, and all 22 were assessed on combination therapy. The plasma levels achieved at the time of each hemodynamic assessment were in the therapeutic range. At rest, verapamil alone significantly lowered systemic arterial pressure and vascular resistance; metoprolol alone lowered heart rate and increased systemic vascular resistance without change in systemic arterial pressure. Combination therapy reduced systemic arterial pressure and heart rate without change in cardiac output and systemic vascular resistance. During upright bicycle exercise, the changes were directionally similar. Depression of cardiac function (i.e., reduced cardiac output at increased pulmonary artery occluded pressure) occurred following metoprolol but not following verapamil; the addition of verapamil did not accentuate the depression of function induced by metoprolol. These results suggested that in patients with stable coronary artery disease, without manifest conduction system abnormality, the cardiac depressant actions of verapamil were countered by its vasodilator properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise and hypertension

Hypertension is a major risk factor for atherosclerosis. In this article the authors review the use of physical activity as therapy for elevated blood pressure and explore the hemodynamic effects of exercise among patients with treated and untreated hypertension. Recommendations concerning the use of exercise in the management of hypertension are outlined.

Pharmacologic differences between beta blockers

All of the beta blockers act by antagonizing the actions of the endogenous adrenergic agonists epinephrine and norepinephrine at the beta-adrenergic receptors. However, a number of pharmacologic differences exist between the various agents. Some drugs, such as atenolol and metoprolol, are relatively selective for the beta-1-adrenergic receptors, requiring higher concentrations to block beta-2-adrenergic receptors than are required to block beta-1 receptors. It should be noted, however, that these selective beta blockers all block beta-2 receptors when their concentrations are high enough. When patients with asthma must receive a beta blocker, low doses of a selective drug should be used. Recent studies, however, have suggested that the use of a nonselective beta blocker may be desirable to antagonize some beta-2-mediated metabolic effects, such as hypokalemia, induced by epinephrine. Pindolol is the only beta-receptor antagonist available in the United States with intrinsic sympathomimetic, or partial agonist, activity. Such drugs, because of their partial agonist activity, cause some sympathetic stimulation under conditions of low endogenous sympathetic tone, such as while subjects are at rest in the supine position. Under conditions of higher sympathetic tone, pindolol blocks the effects of the endogenous agonists, producing the characteristic effects of a beta blocker. Membrane-stabilizing activity was first recognized with propranolol, and the value of this property has been a source of controversy ever since, but recent studies suggest that propranolol may induce electrophysiologic effects by mechanisms other than beta blockade. Pharmacokinetic differences between the drugs are also of importance.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects on left ventricular performance of nifedipine and verapamil in exercise-induced angina pectoris

The differences between slow calcium blocking agents with respect to effects on heart rate, myocardial contractility and atrioventricular conducting time are well described; the relevance of such differences to the treatment of patients with impaired left ventricular function due to coronary heart disease is uncertain. The haemodynamic effects of equivalent hypotensive doses of nifedipine and verapamil were therefore compared in 20 patients with severe angina pectoris associated with angiographically documented coronary artery disease. The plasma concentrations of nifedipine (mean 57 +/- 19; range 27-77 ng/ml) and verapamil (mean 147 +/- 14; range 117-260 ng/ml) at the time of the haemodynamic measurements were of an order usually associated with substantial pharmacodynamic activity. Sitting at rest nifedipine resulted in reduction in systemic arterial pressure (P less than 0.05) and vascular resistance (P less than 0.01); both the heart rate (P less than 0.01) and cardiac output (P less than 0.05) increased without any significant change in the left heart filling pressure. In contrast, verapamil, which similarly reduced systemic blood pressure (P less than 0.05) and vascular resistance (P less than 0.01), increased cardiac output (P less than 0.05) and left heart filling pressure (P less than 0.05) without any change in heart rate. During upright bicycle exercise both drugs attenuated the angina induced in all subjects during the control exercise period. Despite reductions in systemic blood pressure and vascular resistance the cardiac output was unaltered on either drug at the same workload as in the control assessment. The reduction in exercise blood pressure following nifedipine induced a reflex tachycardia; this was not present, despite the similar hypotensive action, after verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of haemodynamic dose-response effects of beta- and alpha-beta-blockade in acute myocardial infarction

The comparative haemodynamic dose-response effects of beta- (propranolol) or alpha- plus beta-blockade (labetalol) were evaluated in a randomised between-group study of 16 patients with an uncomplicated acute myocardial infarction. In equivalent beta-blocking doses both drugs equally reduced myocardial stroke work index and presumably myocardial oxygen requirements. However, although propranolol reduced heart rate and cardiac output, these haemodynamic changes were accompanied by an augmentation of systemic vascular resistance. In contrast, labetalol reduced heart rate, cardiac output without change in systemic vascular resistance. Moreover, concomitant alpha- and beta-blockade with labetalol resulted in lesser depression of cardiac output at equivalent beta-blocking doses to propranolol. These results suggest that the addition of alpha to beta-blockade may attenuate some of the adverse reflex circulatory consequences of pure beta-blockade; the usefulness of this pharmacological approach to the manipulation of the circulation in the early post-infarction period merits further study.