Effects of nifedipine on myocardial perfusion during exercise in chronic stable angina pectoris

Pharmacotherapy of Vasospastic Angina

Vasospastic angina is a diagnosis of exclusion that manifests with signs and symptoms, which overlap with obstructive coronary artery disease, most often ST-segment elevation myocardial infarction. The pharmacotherapy that is available to treat vasospastic angina can help ameliorate angina symptoms. However, the etiology of vasospastic angina is ill-defined, making targeted pharmacotherapy difficult. Most patients receive pharmacotherapy that includes calcium channel blockers and/or long-acting nitrates. This article reviews the efficacy and safety of the pharmacotherapy used to treat vasospastic angina. High-dose calcium channel blockers possess the most evidence, with respect to decreasing angina incidence, frequency, and duration. However, not all patients respond to calcium channel blockers. Nitrates and/or alpha1-adrenergic receptor antagonists can be used in patients who respond poorly to calcium channel blockers. Albeit, evidence for use of nitrates and alpha1-adrenergic receptor antagonists in vasospastic angina is not as robust as calcium channel blockers and can exacerbate adverse effects when added to calcium channel blocker therapy. Despite having a clear benefit in patients with obstructive coronary artery disease, the benefit of beta-adrenergic receptor antagonists, statins, and aspirin remains unclear. More data are needed to elucidate whether or not these agents are beneficial or harmful to patients being treated for vasospastic angina. Overall, the use of pharmacotherapy for the treatment of vasospastic angina should be guided by patient-specific factors, such as tolerability, adverse effects, drug–drug, and drug–disease interactions.

The calcium-channel blocker controversy: historical perspective and important lessons for future pharmacotherapies. An international society of pharmacoepidemiology 'hot topic'

Reports of adverse events in association with calcium-channel blockers led to heated controversy over the safety and efficacy of these drugs, as well as to panic among the general public. At the 1998 International Conference of Pharmacoepidemiology, four experts were asked to summarize, and draw lessons from, the controversy's development. We conducted our own review in order to provide a broader historical perspective on the subject and to present the discussants' views within the framework of additional published opinions. Several years after the controversy's onset, many uncertainties still remain about the merits of CCBs. Yet the media scare generated by a few studies might have been prevented had investigators placed greater emphasis, particularly in their reports to the media, on the limitations of their observational and meta-analytic designs. These studies, however, did call attention to the persistent use of CCBs for off-label indications, and the imperative to improve clinician prescribing practices. Moreover, they showed the pitfalls of reliance on surrogate endpoints, stressing the need for data on major clinical outcomes-with funding a responsibility of the pharmaceutical industry-before approving drugs destined for widespread, long-term use. Attention to these lessons will do us well as we evaluate emerging pharmacotherapies. Copyright (c) 2000 John Wiley & Sons, Ltd.

Recent advances in the management of chronic stable angina II. Anti-ischemic therapy, options for refractory angina, risk factor reduction, and revascularization

The objectives in treating angina are relief of pain and prevention of disease progression through risk reduction. Mechanisms, indications, clinical forms, doses, and side effects of the traditional antianginal agents - nitrates, β-blockers, and calcium channel blockers - are reviewed. A number of patients have contraindications or remain unrelieved from anginal discomfort with these drugs. Among newer alternatives, ranolazine, recently approved in the United States, indirectly prevents the intracellular calcium overload involved in cardiac ischemia and is a welcome addition to available treatments. None, however, are disease-modifying agents. Two options for refractory angina, enhanced external counterpulsation and spinal cord stimulation (SCS), are presented in detail. They are both well-studied and are effective means of treating at least some patients with this perplexing form of angina. Traditional modifiable risk factors for coronary artery disease (CAD) - smoking, hypertension, dyslipidemia, diabetes, and obesity - account for most of the population-attributable risk. Individual therapy of high-risk patients differs from population-wide efforts to prevent risk factors from appearing or reducing their severity, in order to lower the national burden of disease. Current American College of Cardiology/American Heart Association guidelines to lower risk in patients with chronic angina are reviewed. The Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial showed that in patients with stable angina, optimal medical therapy alone and percutaneous coronary intervention (PCI) with medical therapy were equal in preventing myocardial infarction and death. The integration of COURAGE results into current practice is discussed. For patients who are unstable, with very high risk, with left main coronary artery lesions, in whom medical therapy fails, and in those with acute coronary syndromes, PCI is indicated. Asymptomatic patients with CAD and those with stable angina may defer intervention without additional risk to see if they will improve on optimum medical therapy. For many patients, coronary artery bypass surgery offers the best opportunity for relieving angina, reducing the need for additional revascularization procedures and improving survival. Optimal medical therapy, percutaneous coronary intervention, and surgery are not competing therapies, but are complementary and form a continuum, each filling an important evidence-based need in modern comprehensive management.

Clinical and research issues regarding chronic advanced coronary artery disease part II: Trial design, outcomes, and regulatory issues

The population of patients with advanced coronary artery disease (CAD) is growing as a result of the aging of the general population, the extensive use of revascularization, and the efficacy of therapies that have prolonged the survival of patients with severe atherosclerosis. Patients with symptomatic CAD survive to a point where little else can be done to relieve their angina. Despite an anticipated growth in the number of patients with this condition within the next few decades, advanced CAD receives relatively little attention by the medical and research communities. As a result, the scope of the disease is not well defined, its coverage in guidelines from professional associations is limited, and few new medical options are available. In response to this, a group of experts from different fields were brought together at a meeting held December 4 to 5, 2006. This document has been developed as a 2-part article. In the first part, the contemporary and emerging therapies for advanced CAD were reviewed. The present part reviews the current status of understanding of advanced CAD, the limits of contemporary therapies, and the difficulties in and barriers to the development of new treatments.

A randomized, double-blind comparison of lercanidipine 10 and 20 mg in patients with stable effort angina: clinical evaluation of cardiac function by ambulatory ventricular scintigraphic monitoring

We evaluated the antiischemic action and the effects on left ventricular response to exercise of lercanidipine, a long-acting dihydropyridine calcium antagonist, in 23 patients with stable effort angina in a randomized, double-blind, parallel trial. Left ventricular function was assessed during upright bicycle exercise using an ambulatory radionuclide detector for continuous noninvasive monitoring of cardiac function. Exercise was performed under control conditions before (run-in placebo period) and after 2-week treatment with lercanidipine 10 or 20 mg once daily. During the placebo run-in period and at the study end, patients underwent clinical examination, ECG, exercise tests, ambulatory ventricular scintigraphic monitoring (VEST). Results showed that both drug doses increased time to onset of ST segment depression >/=1 mm and peak ST segment depression, with improvement of total exercise duration. Heart rate, blood pressure, and the rate-pressure product did not significantly change with respect to pretreatment value. The left ventricular ejection fraction, indicating contractility state of myocardium, was unchanged at rest and during exercise after both lercanidipine doses. In conclusion, lercanidipine is safe and effective in reducing ischemia in patients with stable effort angina without any deterioration of cardiac function.

Optimal medical management of angina

Coronary artery disease remains one of the principal causes of disability worldwide. Its most common manifestation is angina pectoris. Angina occurs due to an imbalance between myocardial oxygen demand and supply; it is classically precipitated by physical activity, emotion, eating, or cold weather. It is defined as stable when its frequency, severity, duration, time of appearance, and precipitating factors remain unchanged for 60 days. Treatment of patients with stable angina targets a number of factors that underlie its pathophysiology: aspirin as an antiplatelet agent, b-blockade to reduce myocardial oxygen demand, and additional antianginal drugs when symptoms are incompletely controlled by b-blockers alone. Furthermore, aggressive treatment of risk factors for the development of coronary artery disease confers a significant mortality benefit. Unstable angina is defined as symptoms developing at rest, on minimal exertion, and of increasing severity, duration, or frequency. It is associated with significant mortality; consequently, early assessment and intervention is essential to prevent worsening ischemia. Treatment includes close in-patient monitoring, administration of antiplatelet and antithrombotic drugs, and a combination of b-blockers, calcium antagonists, and intravenous nitrates where appropriate. Coronary revascularization should be considered in high-risk patients, and when conservative management strategies fail.

A randomized, double-blind comparison of 10 and 20 mg lercanidipine in patients with stable effort angina: effects on myocardial ischemia and heart rate variability

We evaluated the anti-ischemic action and the effects on autonomic function of lercanidipine, a long-acting dihydropyridine calcium antagonist, in 25 patients with stable effort angina in a randomized, double-blind, parallel trial. After a 2-week placebo run-in period, patients entered a 2-week treatment period with 10 or 20 mg of lercanidipine once daily. During the placebo run-in period and at the study end, the patients underwent clinical examination, electrocardiography, exercise tests, 24-hour Holter electrocardiography for long-term heart rate variability evaluation, and short-term spectral analysis of heart rate and systolic blood pressure variability and plasma epinephrine and norepinephrine levels at rest and during tilting. Results showed that time to onset of ST segment depression > or =1 mm was significantly increased by both drug doses. No significant change was recorded in the average hourly heart rate after treatment with both 10 and 20 mg of lercanidipine. During the 24-hour recordings, no significant change was observed in low-frequency power, high-frequency power, or low frequency/high frequency. In the standing position, there was a significant increase in plasma norepinephrine and epinephrine concentration in both groups, and no change in the supine position after 10 and 20 mg of lercanidipine. When considering short-term heart rate variability, no significant difference was observed in either treatment group in low frequency, high frequency, or their ratio on electrocardiographic R-R spectra. The blood pressure spectral component was also unchanged. In conclusion, lercanidipine is effective in reducing ischemia in patients with stable effort angina. Moreover, lercanidipine does not cause adrenergic activation, which is the main mechanism hypothesized to explain the negative effect on cardiovascular mortality assigned to short-acting dihydropyridine calcium antagonists.

The multicenter study of enhanced external counterpulsation (MUST-EECP): effect of EECP on exercise-induced myocardial ischemia and anginal episodes

OBJECTIVES

The purpose of this study was to assess safety and efficacy of enhanced external counterpulsation (EECP).

BACKGROUND

Case series have shown that EECP can improve exercise tolerance, symptoms and myocardial perfusion in stable angina pectoris.

METHODS

A multicenter, prospective, randomized, blinded, controlled trial was conducted in seven university hospitals in 139 outpatients with angina, documented coronary artery disease (CAD) and positive exercise treadmill test. Patients were given 35 h of active counterpulsation (active CP) or inactive counterpulsation (inactive CP) over a four- to seven-week period. Outcome measures were exercise duration and time to > or =1-mm ST-segment depression, average daily anginal attack count and nitroglycerin usage.

RESULTS

Exercise duration increased in both groups, but the between-group difference was not significant (p > 0.3). Time to > or =1-mm ST-segment depression increased significantly from baseline in active CP compared with inactive CP (p = 0.01). More active-CP patients saw a decrease and fewer experienced an increase in angina episodes as compared with inactive-CP patients (p < 0.05). Nitroglycerin usage decreased in active CP but did not change in the inactive-CP group. The between-group difference was not significant (p > 0.7).

CONCLUSIONS

Enhanced external counterpulsation reduces angina and extends time to exercise-induced ischemia in patients with symptomatic CAD. Treatment was relatively well tolerated and free of limiting side effects in most patients.

Rationale for the use of calcium antagonists in the treatment of silent myocardial ischemia

Silent myocardial ischemia, whether it occurs at rest or during exercise, is associated with an unfavorable prognosis and may lead to sudden cardiac death. Agents used to treat silent myocardial ischemia have included nitrates, beta-blockers, and calcium antagonists (CAs). Despite treatment with traditional anti-ischemic agents, studies have shown that up to 40% of patients who receive what is considered to be clinically optimal antianginal therapy continue to have daily episodes of silent myocardial ischemia. The use of nitrates and beta-blockers is sometimes confounded by issues of tolerance and tolerability. Although the CAs have been found to be effective in decreasing the duration and frequency of episodes of silent ischemia, in general beta-blockers produce a greater reduction in these variables. Thus a need for effective and tolerable anti-ischemic agents persists. A new class of CAs, the tetralol derivatives, may show promise in this regard. The first of this new class, mibefradil, is characterized by selective blockade of T-type calcium-ion channels and has been shown in a few studies to reduce the frequency and duration of asymptomatic ischemic episodes in patients with stable exertional angina pectoris. Large-scale clinical trials are necessary before the efficacy and tolerability of this new CA can be compared fully with those of the beta-blockers and currently available CAs.

Nifedipine gastrointestinal therapeutic system versus atenolol in stable angina pectoris. The Netherlands Working Group on Cardiovascular Research (WCN)

The gastrointestinal therapeutic system formulation of nifedipine enables a once-daily dosing resulting in predictable, relatively constant plasma concentrations. To evaluate the efficacy and safety of this formulation and to compare this with the beta-blocker atenolol, we conducted a double-blind, randomised, multi-centre study in 129 male patients with documented exercise induced angina pectoris. After 4 weeks' treatment, nifedipine (60 mg), improved time to onset of 0.1 mV ST-segment depression from 536 s by 72 +/- 117s, time to onset of pain from 619 s by 56 +/- 120 s, and total exercise time from 685 s by 40 +/- 88 s. Atenolol 100 mg, had a comparable effect, time to onset of 0.1 mV ST-segment depression improved from 496 s by 53 +/- 129 s, time to onset of pain from 572 s by 57 +/- 118 s, and total exercise time from 653 s by 33 +/- 99 s. Between group analysis revealed no statistically significant differences for these exercise parameters. Atenolol, but not nifedipine, significantly reduced heart rate and systolic blood pressure at rest and during exercise (P < 0.001 between groups), indicating different modes of action of the drugs. With regard to safety, both drugs were generally well tolerated. There were significantly (P = 0.01) more vasodilation related side effects with nifedipine. These data demonstrate that gastrointestinal therapeutic system formulation of nifedipine and atenolol as once-daily monotherapy are equally effective and safe, but with different effects on exercise parameters.

Calcium channel blockers in heart failure: help or hindrance?

Since their development, calcium channel blocking agents have stimulated interest in their potential benefit for a variety of cardiovascular disorders, including heart failure. The rationale for the potential benefit of calcium channel blockers in heart failure is multi-factorial, including vasodilation, correction of perturbed diastolic relaxation, anti-ischemic action, and potential for inhibiting myocyte hypertrophy and injury. Despite these potential benefits, the degree of salutary influence has remained controversial, and a number of studies have suggested potential adverse action in patients with heart failure, perhaps linked to either negative inotropic action or to reflex neurohormonal activation. Diversity among different agents, particularly with regard to tissue selectivity and pharmacokinetics may imply substantial differences in the relative benefits and risks in various subgroups of patients with heart failure. One trial with the newer dihydropyridine agent, amlodipine, indicates benefit to survival in patients with moderate to severe heart failure and reduced ejection fraction. The reproducibility of this finding and the mechanism for this benefit deserves further investigation.

Calcium antagonists in patients with left ventricular dysfunction: back on the bridge?

Calcium antagonists have a useful role in the management of patients with cardiac disease, producing coronary and systemic vasodilatation and an additional possibly beneficial effect on ventricular diastolic function. On the other hand, the myocardial depressant effect of the first-generation drugs and the abrupt changes in blood pressure, with neurohormonal activation, have been associated with worsening heart failure in certain patients. The present review summarizes the data currently available, with emphasis on the newer slow-release and long-acting calcium antagonists. Use of these drugs minimizes the peak and trough effect associated with short-acting preparations, and particularly when administered against a background of digoxin, diuretic and angiotensin converting enzyme inhibitors, may be associated with better long-term results in patients with ventricular dysfunction. The DEFIANT studies, using nisoldipine-coat core, showed that nisoldipine-CC improved diastolic ventricular function and had a significant anti-ischemic effect in patients with mild-moderate ventricular dysfunction after acute myocardial infarction. The VHeFT III trial showed that felodipine had no effect on exercise capacity or survival in patients with Class 2-3 heart failure. In the PRAISE study of Class 3-4 patients, amlodipine was neutral in patients with ischemic disease, but a strikingly beneficial effect was observed in non-ischemic heart failure (45% decrease in mortality). The precise mechanism for the beneficial effect of amlodipine in these patients is unknown. Further studies are needed to examine the issue of survival benefit in patients with non-ischemic heart failure and the mechanisms involved.

Calcium antagonists and mortality in patients with coronary artery disease: a cohort study of 11,575 patients

OBJECTIVES

This study sought to establish the risk ratio for mortality associated with calcium antagonists in a large population of patients with chronic coronary artery disease.

BACKGROUND

Recent reports have suggested that the use of short-acting nifedipine may cause an increase in overall mortality in patients with coronary artery disease and that a similar effect may be produced by other calcium antagonists, in particular those of the dihydropyridine type.

METHODS

Mortality data were obtained for 11,575 patients screened for the Bezafibrate Infarction Prevention study (5,843 with and 5,732 without calcium antagonists) after a mean follow-up period of 3.2 years.

RESULTS

There were 495 deaths (8.5%) in the calcium antagonist group compared with 410 in the control group (7.2%). The age-adjusted risk ratio for mortality was 1.08 (95% confidence interval [CI] 0.95 to 1.24). After adjustment for the differences between the groups in age and gender and the prevalence of previous myocardial infarction, angina pectoris, hypertension, New York Heart Association functional class, peripheral vascular disease, chronic obstructive pulmonary disease, diabetes and current smoking, the adjusted risk ratio declined to 0.97 (95% CI 0.84 to 1.11). After further adjustment for concomitant medication, the risk ratio was estimated at 0.94 (95% CI 0.82 to 1.08).

CONCLUSIONS

The current analysis does not support the claim that calcium antagonist therapy in patients with chronic coronary artery disease, whether myocardial infarction survivors or others harbors an increased risk of mortality.

Sustained release nifedipine formulations. An appraisal of their current uses and prospective roles in the treatment of hypertension, ischaemic heart disease and peripheral vascular disorders

Nifedipine antagonises influx of calcium through cell membrane slow channels, and sustained release formulations of the calcium channel blocker have been shown to be effective in the treatment of mild to moderate hypertension and both stable and variant angina pectoris. Preliminary findings also indicate that these formulations are effective in the treatment of Raynaud's phenomenon and hypertension in pregnancy, and that they reduce the frequency of ischaemic episodes in some patients with silent myocardial ischaemia. The exact mechanism of action of nifedipine in all of these disorders has not been defined. However, its potent peripheral and coronary arterial dilator properties, together with improvements in oxygen supply/demand, are of particular importance. A major goal of sustained release therapy is to permit reductions in the frequency of nifedipine administration, preferably to once daily, and thus improve patient compliance. Two new once-daily formulations--the nifedipine gastrointestinal therapeutic system (GITS) and a fixed combination capsule comprising sustained release nifedipine 20 mg and atenolol 50 mg--have exhibited marked antihypertensive efficacy. The GITS preparation has also been used effectively in the treatment of stable angina pectoris, and both formulations appear to be well tolerated. Sustained release nifedipine formulations are generally better tolerated than their conventionally formulated counterparts, particularly with regard to reflex tachycardia. Adverse effects seem to be dose related, are mainly associated with the drug's potent vasodilatory action, and include headache, flushing and dizziness. Generally, these effects are mild to moderate in severity and transient, usually diminishing with continued treatment. Thus, sustained release nifedipine formulations are useful and established cardiovascular therapeutic agents which have demonstrable efficacy in various forms of angina, mild to moderate hypertension and Raynaud's phenomenon. Further, promising results shown by the nifedipine GITS formulation, with its advantage of once daily administration suggest that it is likely to become one of the preferred nifedipine formulations for the treatment of hypertension and the various forms of angina.

Comparison of propranolol, diltiazem, and nifedipine in the treatment of ambulatory ischemia in patients with stable angina. Differential effects on ambulatory ischemia, exercise performance, and anginal symptoms. The ASIS Study Group

Episodes of transient myocardial ischemia during ambulatory activities are common in patients with stable coronary artery disease and who are often asymptomatic. Selection of therapy for episodes of asymptomatic ischemia is limited by a lack of direct comparative studies. To determine the most effective monotherapy for patients with stable angina and a high frequency of asymptomatic ischemic episodes, propranolol-LA (mean daily dose, 293 mg), diltiazem-SR (mean daily dose, 350 mg), nifedipine (mean daily dose, 79 mg) were each compared with placebo, each for 2 weeks, in a randomized, double-blinded, crossover trial. Entry criteria were a positive exercise treadmill test during placebo therapy characterized by 1.0 mm or more ST segment depression and angina pectoris, and six or more episodes of transient ST segment depression of 1.0 mm or more on a 48-hour ambulatory electrocardiogram. One hundred ninety-four patients were screened, 63 were eligible and received randomized therapy, of which 56 patients completed at least two of the four treatment periods and were included in an intent-to-treat analysis. Fifty patients completed all four treatment phases and were included in the protocol-completed analysis. Anti-ischemia efficacy was assessed by 48-hour ambulatory electrocardiographic monitoring, exercise treadmill tests, and anginal diaries. Ninety-four percent of all episodes of ambulatory ischemia were asymptomatic. Compared with placebo, only propranolol was associated with a marked reduction in all manifestations of asymptomatic ischemia during ambulatory electrocardiographic monitoring (2.3 versus 1.0 episodes/24 hr; mean duration of ischemia per 24 hours, 43.6 versus 5.7 minutes; both p less than 0.0001). Diltiazem's reduction of the frequency of episodes compared with placebo (2.3 versus 1.9 episodes/24 hr) was associated with a trend (p = 0.08) in the protocol-completed analysis and with a significant reduction in the intent-to-treat analysis (p = 0.03). Nifedipine had no significant effect on any measured variable of ambulatory ischemia. The dosages of medication used may have been excessive for some patients, and a more beneficial effect may have been evident at a lower dose. In contrast to the marked effects of the active agents on ambulatory asymptomatic ischemia, the effects on exercise performance and angina pectoris were slight. The active agents modestly improved treadmill exercise duration time until 1 mm ST segment depression (3%), and only propranolol and diltiazem had significant effects. Only diltiazem significantly prolonged the total exercise time. Anginal frequency was significantly decreased by both propranolol and diltiazem.(ABSTRACT TRUNCATED AT 400 WORDS)