Response of angina and ischemia to long-term treatment in patients with chronic stable angina: a double-blind randomized individualized dosing trial of nifedipine, propranolol and their combination

Characterisation and fundamental insight into the formation of new solid state, multicomponent systems of propranolol

The physiochemical properties of acidic or basic active pharmaceutical ingredients (APIs) can be optimised by forming salts with different counterions. The aim of this work was to synthesise a novel salt of propranolol (PRO) using sebacic acid (SEBA) as the counterion and to gain mechanistic understanding of not only the salt formation, but also its eutectic phase formation with SEBA. Thermal analysis showed a solid-state reaction occurring between PRO and SEBA leading to the formation of dipropranolol sebacate (DPS) melting at app. 170 °C and the eutectic composed of DPS and SEBA melting at app. 103 °C, comprising 0.33 mol fraction of PRO as determined by the Tammann plot. X-ray diffraction and Fourier-transform infrared spectroscopy (FTIR) confirmed the identity of the new multicomponent phases of PRO. DPS can be conveniently obtained by heat-induced crystallisation, grinding and conventional solvent crystallisation. Detailed analysis by FTIR revealed H-bond interactions between DPS and SEBA at the inter-phase in the eutectic. Bravais, Friedel, Donnay and Harker crystal morphology coupled with full interaction maps analysis allowed to understand further the nature of interactions which led to formation of the eutectic phase. This work contributes to furthering research on multicomponent pharmaceutical systems to harness their full potential.

Association Between β-Blockers and Outcome of Coronary Artery Bypass Grafting: Before and After 1 Year

BACKGROUND

We evaluated the long-term outcomes of coronary artery bypass grafting (CABG) according to β-blocker therapy using landmark analysis. Although β-blockers have been shown to improve outcomes for ischemic heart disease, the long-term effects and optimal treatment duration of use after CABG remain unknown.

METHODS

From January 2001 to December 2014, 5382 CABG patients were stratified into 2 groups according to β-blocker therapy at discharge (β-blocker group: 3677 [68.3%], no β-blocker group: 1705 [31.7%]).

RESULTS

The primary outcome was all-cause death during 48 months of follow-up. Using propensity score-matched analysis, β-blocker therapy was associated with all-cause death during the 48-month follow-up (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.41-0.95; P = .03). The landmark analysis demonstrated that the effect of β-blockers on all-cause death was particularly significant within the first 12 months of therapy (HR, 0.37; 95% CI, 0.19-0.80; P = .01) but not after 12 months (HR, 0.92; 95% CI, 0.56-1.53; P = .77).

CONCLUSIONS

The benefits of postdischarge β-blockers may be limited to 1 year after CABG, but further studies are required to confirm this finding.

Beta-Blockers, Calcium Channel Blockers, and Mortality in Stable Coronary Artery Disease

PURPOSE OF REVIEW

To examine the current clinical evidence behind the use of calcium channel blockers (CCB) and beta-blockers (BB) for the treatment of patients with stable coronary artery disease (SCAD) and their effect on mortality.

RECENT FINDINGS

Current evidence suggests that BB use as a first line antianginal medication is associated with lower 5-year all-cause mortality only in patients who had MI within a year. This could be driven due to their effects reducing the sympathetic neuro-hormonal activation of more acutely ill patients. The use of CCB as an antianginal therapy, although proven effective in multiple trials both as monotherapy and combined with other agents, has not shown mortality benefit. Both BB and CCB are effective antianginals, and the selection among them depends on the patient clinical presentation and comorbidities. BB are the only ones that have shown survival benefit in SCAD, particularly the first year post-MI.

Management of Angina Post Percutaneous Coronary Intervention

PURPOSE OF REVIEW

Our review discusses the management of post percutaneous coronary intervention angina (PPCIA) which negatively impacts 20-40% of patients and imposes a high burden on the healthcare system.

RECENT FINDINGS

Mechanisms of PPCIA include microvascular dysfunction, distal coronary vasospasm or disease, microembolization, myocardial bridge, coronary artery disease (CAD) progression, and rarely stent thrombosis or in-stent restenosis. Nitrates, beta blockers (BB), calcium channel blockers, and ranolazine are the common medical management options. Only BB showed 1-year mortality benefit following myocardial infarction. Stress echocardiography and cardiac magnetic resonance are the best to detect CAD vs. microvascular dysfunction. Invasively, vasoprovocative testing and fractional flow reserve provide useful prognostic information. If the ischemia burden is ≤10%, conservative management should be considered based upon the individual patient scenario. The optimal management of PPCIA remains unclear and further research is necessary. Multiple treatment options exist, which should be implemented in an individualized fashion.

Association between perioperative β-blocker use and clinical outcome of non-cardiac surgery in coronary revascularized patients without severe ventricular dysfunction or heart failure

Perioperative use of β-blocker has been encouraged in patients undergoing non-cardiac surgery despite weak evidence, especially in patients without left ventricular systolic dysfunction (LVSD) or heart failure (HF). This study evaluated the effects of perioperative β-blocker on clinical outcomes after non-cardiac surgery among coronary revascularized patients without LVSD or HF. Among a total of 503 patients with a history of coronary revascularization (either by percutaneous coronary intervention or coronary arterial bypass grafts) undergoing non-cardiac surgery, those without severe LVSD defined by ejection fraction over 30% or HF were evaluated. The primary outcome was a composite of death, myocardial infarction, repeat revascularization, and stroke during 1-year follow-up. Perioperative β-blocker was used in 271 (53.9%) patients. During 1-year follow-up, we found no significant difference in primary outcome between the two groups on multivariate analysis (hazard ratio [HR], 1.01; confidence interval [CI] 95%, 0.56–1.82; P = 0.963). The same result was shown in propensity-matched population (HR, 1.25; CI 95%, 0.65–2.38; P = 0.504). In coronary revascularized patients without severe LVSD or HF, perioperative β-blocker use may not be associated with postoperative clinical outcome of non-cardiac surgery. Larger registry data is needed to support this finding.

The Impact of De-escalation of Antianginal Medications on Health Status After Percutaneous Coronary Intervention

BACKGROUND

Antianginal medications (AAMs) can be perceived to be less important after percutaneous coronary intervention (PCI) and may be de-escalated after revascularization. We examined the frequency of AAM de-escalation at discharge post-PCI and its association with follow-up health status.

METHODS AND RESULTS

In a 10-center PCI registry, the Seattle Angina Questionnaire was assessed before and 6 months post-PCI. AAM de-escalation was defined as fewer AAMs at discharge versus admission or >25% absolute dose decrease. Of 2743 PCI patients (70% male), AAM were de-escalated, escalated, and unchanged in 299 (11%), 714 (26%), and 1730 (63%) patients, respectively. Patients whose AAM were de-escalated were more likely to report angina at 6 months, compared with unchanged or escalated AAM (34% versus 24% versus 21%; P<0.001). The association of AAM de-escalation with health status was examined using multivariable models adjusting for the predicted risk of post-PCI angina, completeness of revascularization, and the interaction of AAM de-escalation×completeness of revascularization. There was a significant interaction between AAM de-escalation and completeness of revascularization (P<0.001), suggesting that AAM de-escalation was associated with greater impairment of health status among patients with incomplete revascularization. In patients with incomplete revascularization, de-escalation of AAM at discharge was associated with 43% increased angina risk (relative risk, 1.43; 95% confidence interval, 1.26-1.63) and worse angina-related health status at 6 months post-PCI.

CONCLUSIONS

De-escalation of AAM occurs in 1 in 10 patients post-PCI, and it is associated with an increased risk of angina and worse health status, particularly among those with incomplete revascularization.

Pharmacologic management of chronic stable angina

Chronic stable angina is a significant problem in older adults. The goal of therapy is to provide symptomatic relief, improve patient quality of life, and prevent subsequent angina or myocardial infarction that could lead to sudden death. The efficacy and safety of drugs such as beta-blockers and calcium channel blockers for managing chronic stable angina in older adults has not been rigorously investigated. Drug selection should be based on physiologic alterations, patient comorbidities, adverse reaction profile, and cost.

Experimental and early investigational drugs for angina pectoris

INTRODUCTION

Ischemic heart disease (IHD) is a major cause of death and disability among Western countries and angina pectoris is the most prevalent symptomatic manifestation. Strategies to improve management of chronic stable angina are a priority. Areas covered: A comprehensive review was conducted using the Medline and Cochrane databases as well as the clinical trial databases in the United States and Europe. Traditional therapies for angina will be discussed. This review particularly emphasizes investigational therapies for angina (including pharmacological agents, cell and gene based therapies, and herbal medications). Expert opinion: There has been renewed interest in older anti-angina agents (e.g., perhexiline, amiodarone, and phosphodiestrase-5 inhibitors). Other anti-inflammatory agents (e.g., allopurinol and febuxostat) are currently undergoing evaluation for angina therapy. Therapeutic angiogenesis continues to face some challenges. Future trials should evaluate the optimum patient population that would benefit from this form of therapy.

β-blocker Therapy is Not Associated with Reductions in Angina or Cardiovascular Events After Coronary Artery Bypass Graft Surgery: Insights from the IMAGINE Trial

Purpose

To evaluate whether β-blockers were associated with a reduction in cardiovascular events or angina after Coronary Artery Bypass Graft (CABG) surgery, in otherwise stable low-risk patients during a mid-term follow-up.

Methods

We performed a post-hoc analysis of the IMAGINE (Ischemia Management with Accupril post–bypass Graft via Inhibition of angiotensin coNverting Enzyme) trial, which tested the effect of Quinapril in 2553 hemodynamically stable patients with left ventricular ejection fraction (LVEF) >40 %, after scheduled CABG. The association between β-blocker therapy and the incidence of cardiovascular events (death, cardiac arrest, myocardial infarction, revascularizations, angina requiring hospitalization, stroke or hospitalization for heart failure) or angina that was documented to be due to underlying ischemia was tested with Cox regression and propensity adjusted analyses.

Results

In total, 1709 patients (76.5 %) were using a β-blocker. Patients had excellent control of risk factors; with mean systolic blood pressure being 121 ± 14 mmHg, mean LDL cholesterol of 2.8 mmol/l, 59 % of patients received statins and 92 % of patients received antiplatelet therapy. During a median follow-up of 33 months, β-blocker therapy was not associated with a reduction in cardiovascular events (hazard ratio 0.97; 95 % confidence interval 0.74–1.27), documented angina (hazard ratio 0.85; 95 % confidence interval 0.61–1.19) or any of the individual components of the combined endpoint. There were no relevant interactions for demographics, comorbidities or surgical characteristics. Propensity matched and time-dependent analyses revealed similar results.

Conclusions

β-blocker therapy after CABG is not associated with reductions in angina or cardiovascular events in low-risk patients with preserved LVEF, and may not be systematically indicated in such patients.

Antagonist molecules in the treatment of angina

INTRODUCTION

Management of chronic angina has evolved dramatically in the last few decades with several options for pharmacotherapy outlined in various evidence-based guidelines.

AREAS COVERED

There is a growing list of drugs that are currently being investigated for treatment of chronic angina. These also include several herbal medications, which are now being scientifically evaluated as potential alternative or even adjunctive therapy for angina. Gene- and cell-based therapies have opened yet another avenue for management of chronic refractory angina in 'no-option' patients who are not candidates for either percutaneous or surgical revascularization and are on optimal medical therapy. An extensive review of literature using PUBMED, Cochrane database, clinical trial databases of the USA and European Union was done and summarized in this review. This review will attempt to discuss the traditional as well as novel therapeutic agents for angina.

EXPERT OPINION

Several pharmacological and non-pharmacological therapeutic options are now available for treatment and management of chronic refractory angina. Renewed interest in traditional therapies and cell- and gene-based modalities with targeted drug delivery systems will open the doors for personalized therapy for patients with chronic refractory angina.

Stable angina pectoris: the medical management of symptomatic myocardial ischemia

Coronary artery disease (CAD) remains an important cause of morbidity and mortality and is a serious public health problem. Over the last 4 decades there have been dramatic advances in the both the prevention and treatment of CAD. The management of CAD was revolutionized by the development of effective surgical and percutaneous revascularization techniques. In this review we discuss the importance of the medical management of symptomatic, stable angina. Medical management approaches to both the treatment and prevention of symptomatic myocardial ischemia are summarized. In Canada, organic nitrates, β-adrenergic blocking agents, and calcium channel antagonists have been available for the therapy of angina for more than 25 years. All 3 classes are of proven benefit in the improvement of symptoms and exercise capacity in patients with stable angina. Although there is no clear first choice within these classes of anti-anginal agents, the presence of prior or concurrent conditions (for example, prior myocardial infarction and/or hypertension) plays an important role in the choice of anti-anginal class in individual patients. For some patients, combinations of different anti-anginal agents can be effective; however it is recommended that this approach be individualized. Although not currently available in Canada, other classes of anti-anginal agents have been developed; their mechanism of action and clinical efficacy is discussed. Patients with stable angina have an excellent prognosis. Patients in this category who obtain relief from symptomatic myocardial ischemia may do well without invasive intervention.

Long-term beta blockers for stable angina: systematic review and meta-analysis

Objectives: To assess the effects of long-term beta blockers in patients with stable angina.

Methods: We reviewed the literature up to June 2010 from CENTRAL, MEDLINE, EMBASE, CBM, and CNKI for randomized controlled trials. The appropriate data were meta-analysed using Revman 5.0.

Results: Twenty-six trials including 6108 patients were identified. The treatment with beta blockers has significantly decreased all-cause mortality when compared with no control (OR 0.40, 95% CI 0.20 to 0.79), but has had no statistically differences when compared with placebo (OR 0.92, 95% CI 0.62 to 1.38) and with calcium-channel blocker (CCB) (OR 0.84, 95% CI 0.49 to 1.44). This was similar in patients with fatal and non-fatal acute myocardial infarction when compared with placebo (OR 0.82, 95% CI 0.57 to 1.17) or CCB (OR 1.08, 95% CI 0.71 to 1.66); on revascularization and quality of life. The beta blockers reduced the incident of unstable angina compared to no treatment (OR 0.14, 95% CI 0.07 to 0.29), but increased unstable angina compared to placebo (OR 3.32, 95% CI 1.50 to 7.36). There was a significant reduction of nitrate consumption when beta blockers were compared with CCBs (OR −1.18, 95% CI −1.54 to −0.82), but not with placebo and trimetazidine. There was no significant difference in angina attack between each group. Side effects in beta blocker were similar with ones in controls.

Conclusions: Beta blockers may decrease the death and unstable angina when compared with no treatment, but no more effective than other anti-anginal agents on prophylaxis of myocardial ischaemia in stable angina patients.

Drug treatment of stable angina pectoris in the elderly: defining the place of calcium channel antagonists

Chronic stable angina pectoris (CSAP) resulting from coronary artery disease (CAD) is common in elderly patients, and significantly reduces their quality of life. Myocardial revascularisation procedures in this age group entail significant risks, largely related to comorbidities rather than advanced age itself. Coronary artery anatomy is more likely to be technically unsuitable for revascularisation and angina more resistant to drug treatment. Therefore, elderly patients often take combinations of antianginal drugs. Calcium channel antagonists (CCAs) are effective antianginal drugs first introduced for clinical use in the late 1970's. They reduce myocardial ischaemia by both causing vasodilatation of coronary resistance vessels and reducing cardiac workload (negative inotropic effect). However, adverse effects related to abrupt arterial vasodilatation limited the tolerability of these short acting 'first generation' drugs (nifedipine, verapamil and diltiazem). Furthermore, short acting nifedipine may occasionally increase both the frequency of angina pectoris and mortality in patients with CAD. Since then, long acting formulations of first generation agents and new chemical entities (second and third generation drugs) have been developed. These are well tolerated and effective at attenuating both myocardial ischaemia and the frequency and severity of angina pectoris in most patients with stable CAD. Current guidelines on the drug treatment of CSAP propose that beta-adrenoceptor antagonists (beta-blockers) should be used as first line medication primarily for their prognostic benefits, and that CCAs need only be introduced if beta-blockers are not tolerated, contraindicated or ineffective. Despite this, there is a wealth of evidence from clinical trials that demonstrate equal antianginal efficacy for CCAs and beta-blockers. The presence of chronic heart failure and prior myocardial infarction are clear indications for the use of beta-blockers in preference to CCAs for the treatment of CSAP. However, in patients with both CSAP and hypertension, second and third generation CCAs may offer prognostic benefits of similar magnitude to those provided by beta-blockers. Therefore, antianginal drug therapy must be tailored to the individual needs and comorbidities of each elderly patient.

Combination of calcium channel blockers and beta-blockers for patients with exercise-induced angina pectoris: beneficial effect of calcium channel blockers largely determined by their effect on heart rate

The combination of calcium channel blockers and beta-blockers is more effective for the treatment of exercise-induced angina pectoris than beta-blocker monotherapy. As ischemia in exercise-induced angina is essentially preceded by an increase in heart rate, calcium channel blockers with a negative chronotropic property may perform better for this purpose than nonchronotropic compounds. A 335-patient, 10-week, double-blind, parallel-group comparison of amlodipine 5 mg and 10 mg, diltiazem 200 mg and 300 mg, and mibefradil 50 mg and 100 mg treatment added to baseline beta-blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. All of the calcium channels blockers significantly delayed the onset of 1 mm ST-segment depression on ETT (p < 0.001 for any treatment vs. baseline). In addition, mibefradil, in both low- and high-dose treatments, produced the largest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 seconds, respectively, p < 0.003 and < 0.001; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 seconds, respectively, p < 0.001 and < 0.001). A stepwise logistic regression analysis revealed that this beneficial effect of calcium channel blockers was largely dependent on their effect on heart rate. Serious symptoms of dizziness likewise occurred significantly more frequently on mibefradil (p < 0.05 vs. diltiazem) and urged no fewer than 19 patients on mibefradil to withdraw from the trial. The authors conclude that calcium channel blockers with a negative chronotropic property provide a better delay of ischemia in patients with exercise-induced angina, but the concomitant risk of intolerable dizziness may reduce this benefit.

Combination of calcium channel blockers and beta blockers for patients with exercise-induced angina pectoris: a double-blind parallel-group comparison of different classes of calcium channel blockers. The Netherlands Working Group on Cardiovascular Research (WCN)

The combination of calcium channel blockers and beta blockers is more effective for the treatment of exercise-induced angina pectoris than beta blocker monotherapy. Since ischemia in exercise-induced angina is essentially preceded by an increase in heart rate, calcium channel blockers with negative chronotropic property may perform better for this purpose than nonchronotropic compounds. A 335-patient, 10-week, double-blind, parallel-group comparison of amlodipine 5 and 10 mg, diltiazem XR 200 and 300 mg, and mibefradil 50 and 100 mg treatment added to baseline beta blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry. Although none of the calcium channel blockers improved duration of exercise or amount of workload, all of them significantly delayed onset of 1 mm ST segment depression on ETT (p<0.001 for any treatment versus baseline). In addition, mibefradil, both low- and high-dose treatment, produced the largest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 s, p<0.003 and <0.001, respectively; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 s, p<0.001 and <0.001, respectively). These effects were linearly correlated to the amount of rate pressure product (RPP) reduction. Serious symptoms of dizziness likewise occurred significantly more frequently with mibefradil (p<0.05) and led 19 patients taking mibefradil to withdraw from the trial. The authors conclude that calcium channel blockers with negative chronotropic property provide better delay of ischemia in patients with exercise-induced angina but that the concomitant risk of intolerable dizziness largely reduces this benefit.

Combination of calcium channel blockers and beta-adrenoceptor blockers for patients with exercise-induced angina pectoris: a double-blind parallel-group comparison of different classes of calcium channel blockers. Netherlands Working Group on Cardiovascular Research (WCN)

AIMS

The combination of calcium channel blockers and beta-adrenoceptor blockers is more effective for the treatment of exercise-induced angina pectoris than beta-adrenoceptor blocker monotherapy. As ischaemia in exercise-induced angina is preceded by increase in heart rate, calcium channel blockers with negative chronotropic properties may perform better for this purpose than nonchronotropic compounds.

METHODS

A 335 patient double-blind parallel-group study comparing 14 day treatment with amlodipine 5 and 10 mg, with diltiazem 200 and 300 mg, and mibefradil 50 and 100 mg added to baseline beta-adrenoceptor blocker treatment was performed. Exercise testing (ETT) was performed by bicycle ergometry.

RESULTS

Although none of the calcium channel blockers improved duration of exercise or amount of workload, all significantly delayed onset of 1 mm ST-segment depression on ETT (P<0.001 for any treatment vs baseline). In addition, mibefradil, both low and high dose treatment, produced the longest delays (low dose: different from diltiazem and amlodipine by 24.1 and 29.8 s, respectively, P<0. 003 and <0.001; high dose: different from diltiazem and amlodipine by 33.7 and 37.0 s, respectively, P<0.001 and <0.001). These effects were linearly correlated with the reduction in rate pressure product (RPP). Serious symptoms of dizziness occurred significantly more frequently on mibefradil (P<0.05), and 19 patients on mibefradil withdrew from trial.

CONCLUSIONS

Calcium channel blockers with negative chronotropic properties provide greater delay of ischaemia in patients with exercise-induced angina, but the concomitant risk of intolerable dizziness attenuates this benefit.

Safety of nifedipine in angina pectoris: a meta-analysis

-Our objective was to compare cardiovascular event rates in patients with stable angina receiving nifedipine as monotherapy or combination therapy and in active drug controls. A MEDLARS search of published articles from 1966 to 1995 in English, French, German, Italian, or Spanish, supplemented by a manual search of bibliographies, identified 60 randomized controlled trials that met protocol criteria. Blinded articles were extracted by 2 physicians. The pooled risks of death, withdrawal, and cardiovascular event were computed and expressed as odds ratios (ORs) for all nifedipine formulations and relative to same study control drug regimens. Thirty cardiovascular events were reported in 2635 nifedipine exposures (1.14%) and 19 events in 2655 other active drug exposures (0.72%). Unadjusted ORs for nifedipine versus controls were 1.40 (95% CI, 0.56 to 3.49) for major events (death, nonfatal myocardial infarction, stroke, revascularization procedure), 1.75 (95% CI, 0.83 to 3.67) for increased angina, and 1.61 (95% CI, 0.91 to 2.87) for all events (major events plus increased angina). Episodes of increased angina were more frequent on immediate-release nifedipine (OR, 4.19 [95% CI, 1.41 to 12.49]) and on nifedipine monotherapy (OR, 2.61 [95% CI, 1.30 to 5.26]). The OR for immediate-release nifedipine was significantly higher than that for sustained-release/extended-release nifedipine (P=0.001), and the OR for nifedipine monotherapy was higher than that for nifedipine combination therapy (P=0.03). Increased risks of cardiovascular events in patients with stable angina on nifedipine were due primarily to more episodes of increased angina, confined to the immediate-release formulation and to nifedipine monotherapy.

Adding the new calcium antagonist mibefradil to patients receiving long-term beta-blocker therapy results in improved antianginal and antiischemic efficacy

OBJECTIVE

The objective of this study was to evaluate the efficacy, tolerability, and safety of mibefradil, a new selective T-type calcium channel blocker, in patients with chronic stable angina pectoris receiving concomitant beta-blocker therapy.

DESIGN

This was a multicenter, double-blind, placebo-controlled study.

METHODS

Ninety-five patients receiving a stable dose of beta-blockers, which was not changed for the purpose of the study, were administered either 50 mg mibefradil once daily for 2 weeks, then 100 mg once daily for 2 weeks, or matching placebo. Efficacy was evaluated by treadmill exercise tolerance testing 24 hours after dose and by diary registration of anginal episodes and nitroglycerin consumption.

RESULTS

Two weeks of treatment with 50 mg mibefradil resulted in a significant increase in symptom-limited exercise duration and a significant delay in the onset of persistent 1 mm ST-segment depression (placebo-corrected treatment effect: 23.2 and 51.7 seconds, respectively). Treatment with the 100 mg dose for 2 additional weeks resulted in a larger improvement in treadmill exercise tolerance testing duration and onset of ischemia (placebo-corrected treatment effect: 52.7 and 75.8 seconds, respectively). In addition, a significant decrease in weekly anginal episodes was observed with the 100 mg dose of mibefradil compared with the effect in the placebo group (-53% vs - 12%, p = 0.037).

CONCLUSIONS

The combined treatment of mibefradil and beta-blockers was well tolerated, and the overall incidence of adverse events was no different from that with beta-blockers alone. The results indicate that adding mibefradil to chronic beta-blocker treatment is associated with significant improvement in efficacy, which is not achieved at the expense of tolerability.

Value of the addition of amlodipine to atenolol in patients with angina pectoris despite adequate beta blockade

Anginal patients who remain symptomatic despite optimally dosed beta blockade may also be given dihydropyridine calcium antagonists. This treatment regimen was examined in a double-blind parallel, randomized, controlled study in 147 patients with angina and positive bicycle exercise tests despite optimal beta blockade with atenolol (heart rate at rest <60 beats/min). Patients were randomized to atenolol and/or placebo (control), and atenolol and/or amlodipine. The main outcome measurement was exercise tolerance after 8 weeks compared with baseline. After 8 weeks, no significant differences in time to 0.1-mV ST-segment depression, time to chest pain, and time to end of exercise were observed. The number of patients with chest pain during exercise decreased significantly in the amlodipine group (p = 0.04 vs controls). The subgroup of patients with an early (<6 minutes) onset of chest pain at baseline showed a significant increase in time to chest pain after amlodipine (p = 0.0001 vs controls). In the amlodipine group, ST depression and rate-pressure product at submaximum comparable workload decreased to 0.4 mm (0.56) (p = 0.03 vs controls) and 1.223 (2.652) beats/ min x mm Hg (p = 0.01 vs controls). The number of patients in each group with adverse events was not different. The addition of amlodipine to the treatment of patients with myocardial ischemia, despite optimal beta blockade, is well tolerated and may lead to improvement in symptomatic anginal patients, who have a rapid onset of exercise-induced ischemia.

Role of beta blockade in the treatment of myocardial ischemia

A number of antianginal drugs and therapeutic strategies are now available for the treatment of patients with coronary artery disease (CAD) and myocardial ischemia. Of the available antianginal drugs, beta blockers appear to be most effective in suppressing myocardial ischemia. The superior anti-ischemic efficacy of beta blockers can be explained by their beneficial actions on hemodynamic parameters, vasomotion, and platelet function. Compared with other anti-ischemic drugs, beta blockers appear to be more efficacious in reducing the magnitude of myocardial ischemia during routine daily activities. In addition, the results of recent studies indicate that treatment with beta blockers not only suppresses myocardial ischemia, but also improves the clinical outcome in patients with CAD. These beneficial effects, along with the well-demonstrated cardioprotective effects of beta blockade in the postinfarction period, clearly suggest that this class of anti-ischemic drugs is an ideal therapeutic choice in most patients with CAD.

Efficacy of mibefradil compared with amlodipine in suppressing exercise-induced and daily silent ischemia: results of a multicenter, placebo-controlled trial

BACKGROUND

Mibefradil is a new benzimidazolyl-substituted tetraline-derivative calcium antagonist. Its vasodilatory activity combined with an ability to lower heart rate without negative inotropic effects as well as its long duration of action make it a promising anti-ischemic agent.

METHODS AND RESULTS

Three hundred nine patients with coronary artery disease, stable angina pectoris, and positive exercise tests were randomized to receive mibefradil (50, 100, or 150 mg), amlodipine (10 mg), or placebo. The anti-ischemic effects of mibefradil on exercise test and silent ischemia parameters were assessed. At doses of 100 and 150 mg, mibefradil increased exercise duration (by 55.5 and 51.0 seconds, respectively; P<.001 for both), increased time to onset of angina (by 98.3 and 82.7 seconds, respectively; P<.001), and increased time to 1-mm ST depression (by 81.7 and 94.3 seconds, respectively; P<.001). By comparison, a 10 mg/d dose of amlodipine significantly improved only time to onset of angina (treatment effect: 38.5 seconds, P=.036). Mibefradil 100 mg and 150 mg decreased the number of episodes of silent ischemia (treatment effects: -3.1 and -3.6, respectively; P<.001) and the duration of silent ischemia (treatment effects: -9.2 minutes, P=.048, and -14.6 minutes, P=.002, respectively). The decrease in the number of episodes of silent ischemia was also statistically significant in the group receiving 10 mg of amlodipine (-1.5; P=.036).

CONCLUSIONS

Once-daily doses of 100 and 150 mg mibefradil were effective in improving exercise tolerance and reducing ischemic episodes during ambulatory monitoring in patients with coronary artery disease.

Effect of morning versus evening dosing of diltiazem on myocardial ischemia detected by ambulatory electrocardiographic monitoring in chronic stable angina pectoris. Dilacor XR Ambulatory Ischemia Study Group

Myocardial ischemia occurs frequently during daily life and has a circadian pattern similar to that reported for myocardial infarction and sudden death. Because of the increased risk of myocardial ischemia in the morning hours, it has been suggested that the administration of anti-ischemic medication before bedtime may be more effective than the traditional morning dosing. This randomized, double-blind, placebo-controlled, crossover study evaluated the effects of 480-mg/day diltiazem (given either in the A.M. or the P.M.) on myocardial ischemia using ambulatory electrocardiographic monitoring in 68 patients with chronic stable angina and > or = 2 minutes of ischemia per 48 hours. During treatment with diltiazem, the duration and number of myocardial ischemic episodes were reduced by 45% (94 to 52 minutes, p <0.004) and by 40% (4.5 to 2.7 episodes, p <0.003), respectively. The duration and number of myocardial ischemic episodes during daytime (6 A.M. to 6 P.M.) hours were also reduced by 52% (74 to 36 minutes, p <0.002) and by 48% (3.1 to 1.6 episodes, p <0.001), respectively. There was no significant difference between A.M. and P.M. dosing. Morning ischemia (6 A.M. to noon), considered separately from daytime ischemia, was also significantly reduced by both A.M. and P.M. dosing regimens, with no difference between the regimens. The results of this study showed that both A.M. and P.M. dosing of long-acting diltiazem were equally effective in suppressing episodes of ambulatory myocardial ischemia at all times.

Combination therapy with metoprolol and nifedipine versus monotherapy in patients with stable angina pectoris. Results of the International Multicenter Angina Exercise (IMAGE) Study

OBJECTIVES

This study was designed to investigate whether combination therapy with metoprolol and nifedipine provides a greater anti-ischemic effect than does monotherapy in individual patients with stable angina pectoris.

BACKGROUND

Combination therapy with a beta-adrenergic blocking agent (which reduces myocardial oxygen consumption) and a dihydropyridine calcium antagonist (which increases coronary blood flow) is a logical approach to the treatment of stable angina pectoris. However, it is not clear whether, in individual patients, this combined therapy is more effective than monotherapy.

METHODS

Two hundred eighty patients with stable angina pectoris were enrolled in a double-blind trial in 25 European centers. Patients were randomized (week 0) to metoprolol (controlled release, 200 mg once daily) or nifedipine (Retard, 20 mg twice daily) for 6 weeks; placebo or the alternative drug was then added for a further 4 weeks. Exercise tests were performed at weeks 0, 6 and 10.

RESULTS

At week 6, both metoprolol and nifedipine increased the mean exercise time to 1-mm ST segment depression in comparison with week 0 (both p < 0.01); metoprolol was more effective than nifedipine (p < 0.05). At week 10, the groups randomized to combination therapy had a further increase in time to 1-mm ST segment depression (p < 0.05 vs. placebo). Analysis of the results in individual patients revealed that 7 (11%) of 63 patients adding nifedipine to metoprolol and 17 (29%) of 59 patients (p < 0.0001) adding metoprolol to nifedipine showed an increase in exercise tolerance that was greater than the 90th percentile of the distribution of the changes observed in the corresponding monotherapy + placebo groups. However, among these patients, an additive effect was observed only in 1 (14%) of the 7 patients treated with metoprolol + nifedipine and in 4 (24%) of the 17 treated with nifedipine + metoprolol.

CONCLUSIONS

The mean additive anti-ischemic effect shown by combination therapy with metoprolol and nifedipine in patients with stable angina pectoris is not the result of an additive effect in individual patients. Rather, it may be attributed to the recruitment by the second drug of patients not responding to monotherapy.

Calcium channel antagonists in the management of anginal syndromes: changing concepts in relation to the role of coronary vasospasm

Despite the increasing evidence that alterations in coronary vascular tone can and do occur in patients with anginal syndromes, only in a minority of such patients with Prinzmetal's angina is there decisive evidence that the coronary vasodilation induced by calcium channel antagonists (CCAs) plays a specific therapeutic role. CCAs may also give therapeutic benefit in a number of conditions in which coronary vasoconstriction may contribute to ischemia, such as hyperventilation, cold-induced angina, or silent ischemia not caused by an increase in heart rate. Thus, the decision of whether or not to use CCAs in angina syndromes will often have to be made on grounds other than what appears to be a minor role of vasospasm in the overall spectrum of angina. There are preliminary indications that the long-term prognosis may be different among different categories of CCAs.

Contemporary approaches in medical management of patients with stable coronary artery disease

CAD continues to be the principal cause of mortality in the United States, and the largest group of patients with CAD are those with stable angina. Among this group of patients, the most common manifestation of CAD is presence of transient episodes of myocardial ischemia. The presence of transient ischemia and not the severity of angina has been found to be associated with poor clinical outcome in patients with stable CAD. As part of a global treatment strategy for patients with stable CAD, changes in lifestyle and modification of coronary risk factors should be emphasized as an integral part of treatment. Conventional antianginal therapy is quite effective in controlling anginal attacks. Currently, several drugs and therapeutic strategies are available for the treatment of patients with angina (see Table 5). Nitrates are highly effective antianginal drugs with complex beneficial actions in patients with CAD, but their usefulness is limited by development of tolerance during long-term use. When clinically indicated, the use of nitrates should be supplemented with another longer-acting antianginal drug, such as a beta-blocker or a calcium channel blocker. Based on the available data, beta-blockers, when tolerated, seem to be the most effective antianginal drugs for most patients with stable CAD. Beta-blockers are also the most effective anti-ischemic drugs that reduce the magnitude of myocardial ischemia detected during routine daily activities. Calcium channel blockers are also effective vasodilators and good antianginal drugs. The clinician should become familiar with the different actions that this heterogeneous group of drugs has on the heart and vessels. This knowledge allows the clinician to choose the appropriate combination of different antianginal drugs for patients on an individualized basis. It is also critical to develop the treatment strategy by carefully taking into account other associated medical conditions that are frequently encountered in patients with CAD.

Effect of amlodipine, atenolol and their combination on myocardial ischemia during treadmill exercise and ambulatory monitoring. Canadian Amlodipine/Atenolol in Silent Ischemia Study (CASIS) Investigators

OBJECTIVES

This study compared the effects of amlodipine, atenolol and their combination on ischemia during treadmill testing and 48-h ambulatory monitoring.

BACKGROUND

It is not known whether anti-ischemic drugs exert similar effects on ischemia during ambulatory monitoring and exercise treadmill testing.

METHODS

Patients with stable coronary artery disease and ischemia during treadmill testing and ambulatory monitoring were randomized to receive amlodipine (n = 51) or atenolol (n = 49). Each group underwent a counterbalanced, crossover evaluation of single drug and placebo, followed by evaluation of the combination.

RESULTS

Amlodipine and the combination prolonged exercise time to 0.1-mV ST segment depression by 29% and 34%, respectively (p < 0.001) versus 3% for atenolol (p = NS). During ambulatory monitoring, the frequency of ischemic episodes decreased by 28% with amlodipine (p = 0.083 [NS]), by 57% with atenolol (p < 0.001) and by 72% with the combination (p < 0.05 vs. both single drugs; p < 0.001 vs. placebo). Suppression of ischemia during exercise testing and ambulatory monitoring was similar in patients with and without exercise-induced angina. Exercise time to angina improved by 29% with amlodipine (p < 0.01), by 16% with atenolol (p < 0.05) and by 39% with the combination (p < 0.005 vs. placebo, atenolol and amlodipine). In patients with angina, total exercise time improved by 16% with amlodipine (p < 0.001), by 4% with atenolol (p = NS) and by 19% with the combination (p < 0.05 vs. placebo and either single drug). In those patients without angina, no therapy significantly improved total exercise time.

CONCLUSIONS

Ischemia during treadmill testing was more effectively suppressed by amlodipine, whereas ischemia during ambulatory monitoring was more effectively suppressed by atenolol. The combination was more effective than either single drug in both settings.

Effects of felodipine versus nifedipine on exercise tolerance in stable angina pectoris

The effects of single doses of felodipine (5 and 10 mg) and nifedipine (10 and 20 mg) on chronic stable effort angina pectoris were assessed in a placebo-controlled, double-blind, crossover study of 24 patients receiving beta blockers and short-acting nitroglycerin. The effects were measured by repeated bicycle ergometer tests. The total work, and time until 1 mm of ST depression increased significantly by 9 to 31% after both active drugs at both dose levels in comparison with placebo. The differences were not significant between drugs or doses. At rest, blood pressure decreased (10 to 15%) and heart rate increased (5 to 10%) significantly after both active drugs. During exercise at the highest comparable work load, systolic blood pressure decreased significantly (23 to 26%), whereas heart rate was not affected after felodipine and nifedipine compared with placebo. The 2 drugs were well tolerated, and side effects were mild. Therefore, single doses of 5 and 10 mg of felodipine, and 10 and 20 mg of nifedipine have similar antianginal and anti-ischemic properties. However, felodipine has a longer duration of action, which may improve compliance.

Comparison of nifedipine gastrointestinal therapeutic system and atenolol on antianginal efficacies and exercise hemodynamic responses in stable angina pectoris

A gastrointestinal therapeutic system (GITS) of nifedipine has been developed to provide a once-daily dosing, and predictable, relatively constant plasma concentrations. This study compared the antianginal efficacy of nifedipine GITS with a once-a-day beta-receptor blocker, atenolol. Seventeen patients with documented coronary artery disease and stable stress-induced angina pectoris were studied during a 2-week, single-blind, placebo baseline phase and a 12-week randomized, double-blind, active drug crossover efficacy phase, using the bicycle exercise test and ambulatory electrocardiographic recordings. Patients exercised significantly longer with nifedipine GITS (883 +/- 47 seconds) and atenolol (908 +/- 44 seconds) than with placebo (794 +/- 41 seconds). Nifedipine GITS reduced systolic blood pressure at all stages of exercise compared with placebo but, because heart rate tended to increase more during nifedipine therapy, there was no difference in rate-pressure products between the placebo and nifedipine GITS periods. In contrast, atenolol reduced heart rate, systolic blood pressure and rate-pressure product during exercise compared with placebo. Whereas left ventricular ejection fractions (by radionuclide angiocardiography) increased with exercise, the maximal increase was smaller with atenolol than with placebo and nifedipine. The net increase in left ventricular ejection fraction at the end of exercise was greater with nifedipine than with placebo or atenolol. Ambulatory electrocardiograms showed only a small number of ischemic events. Neither nifedipine GITS nor atenolol reduced the number of ischemic events or total duration of ST-segment deviations significantly. It is concluded that nifedipine GITS is as effective an antianginal agent as atenolol, but the hemodynamic effects of the 2 agents differ.(ABSTRACT TRUNCATED AT 250 WORDS)