"Maximal" drug therapy is not necessarily optimal in chronic angina pectoris

Monotherapy with amlodipine or atenolol versus their combination in stable angina pectoris

BACKGROUND

The basic cause of angina pectoris is imbalance between the metabolic needs of the myocardium and the capacity of the coronary circulation to deliver sufficient oxygenated blood to satisfy these needs.

HYPOTHESIS

The study was undertaken to evaluate whether the effect of combined amlodipine and atenolol therapy on patients with stable angina pectoris and with ST-depression during exercise testing and 48-h ambulatory electrocardiographic monitoring is superior to that of either agent given alone.

METHODS

Patients with stable angina pectoris and ST depression during exercise and ambulatory monitoring were randomized to receive amlodipine (n = 116) or atenolol (n = 116), or both (n = 119). All patients were also treated with short- and long-acting nitrates. The design was a double-blind, randomized, triple-arm parallel group study with 10 weeks of administration of the test medication.

RESULTS

In terms of time to onset of ST depression > 1 mm, time to onset of angina, total exercise time, maximum achieved workload, and peak intensity of angina, amlodipine and atenolol alone were as effective as their combination. During ambulatory monitoring, atenolol was more effective than amlodipine regarding total time and number of ST-depression episodes, and as effective as the combined drugs.

CONCLUSION

For individual patients with stable angina pectoris, combination of a beta blocker with a calcium antagonist is not necessarily more effective than either drug given alone.

Antianginal Efficacy of Ranolazine When Added to Treatment With Amlodipine

OBJECTIVES

The purpose of this study was to determine if ranolazine improves angina in stable coronary patients with persisting symptoms despite maximum recommended dose of amlodipine.

BACKGROUND

Ranolazine is a unique antianginal agent that has been effective in stable angina, but it has not been studied in the setting of maximum recommended doses of conventional antianginal agents.

METHODS

Stable patients with coronary disease and > or =3 anginal attacks per week despite maximum recommended dosage of amlodipine (10 mg/day) were randomized to 1,000 mg ranolazine or placebo twice a day for 6 weeks. Primary end point was the frequency of angina episodes per week during the double-blind treatment phase. Efficacy was also assessed by nitroglycerin consumption per week and the Seattle Angina Questionnaire (SAQ). Adjustment for multiple testing of secondary end points used a hierarchic closed testing procedure. Efficacy was assessed in subgroups based on baseline angina frequency, concomitant long-acting nitrate use, gender, and age. Safety was assessed by adverse events and electrocardiogram evaluations.

RESULTS

A total of 565 patients were randomized: 281 patients to ranolazine and 284 patients to placebo. Baseline characteristics were similar between treatment groups. At baseline, angina frequency averaged 5.63 +/- 0.18 episodes/week, and nitroglycerin consumption averaged 4.72 +/- 0.21 tablets/week. Compared with placebo, ranolazine significantly reduced frequency of angina episodes (2.88 +/- 0.19 on ranolazine vs. 3.31 +/- 0.22 on placebo; p = 0.028) and nitroglycerin consumption (2.03 +/- 0.20 on ranolazine vs. 2.68 +/- 0.22; p = 0.014), with treatment effect that appeared consistent across subgroups. The median angina weekly episode rate at baseline was 4.5 per week. Subgroup analysis showed statistically significant reductions of angina frequency, nitroglycerin use, and SAQ angina frequency for patients with a baseline frequency >4.5 per week but only of angina frequency for those with baseline frequency < or =4.5 per week. Patients with more frequent angina appeared to have a more pronounced treatment effect. No hemodynamic changes were observed. Ranolazine was well tolerated.

CONCLUSIONS

Ranolazine significantly reduced frequency of angina and nitroglycerin consumption compared with placebo and was well tolerated. (The ERICA [Efficacy of Ranolazine In Chronic Angina] Trial; http://clinicaltrials.gov; NCT00091429).

Selection of optimal therapy for chronic stable angina

Patients with chronic stable angina (CSA) seek a medical opinion for relief of their symptoms and because of fear of having a heart attack. The underlying lesion responsible for CSA is often a severe narrowing of one or more coronary arteries. In addition, the coronary arteries of patients with CSA contain many more nonobstructive lesions, which progress at variable rates, and are prone to rupture and may manifest as acute coronary syndromes (myocardial infarction , unstable angina , or sudden ischemic death). Most patients with CSA can be managed with medical treatment. For angina relief, optimum doses of one of the antianginal drugs (beta blockers , long-acting organic nitrates, or calcium channel blockers ) should be used. If the patient remains symptomatic, combination treatment of BBs plus nitrates or BBs plus dihydropyridine CCBs, or nondihydropyridine CCBs plus nitrates should be tried. Triple therapy has not been shown to be more effective than treatment with two agents. To reduce the incidence of MI, UA, and sudden ischemic death, treatment strategies should include smoking cessation, daily aspirin, daily exercise, and pharmacologic therapy for dyslipidemias, and for elevated blood pressure. Patients who remain symptomatic despite medical therapy and those not willing to take or unable to tolerate antianginal drugs should be considered for percutaneous or surgical coronary revascularization. Patients who do not respond to medical therapy and are not candidates for a revascularization procedure may be considered for additional treatment with trimetazidine or nicorandil (these drugs are not available in the United States or approved by the US Food and Drug Administration, but are available in some other countries). Ranolazine also looks promising but is not yet available for clinical use. As a last resort, enhanced external counterpulsation, spinal cord stimulation, sympathectomy, or direct transmyocardial revascularization should be considered for symptom relief.

Contemporary management of chronic stable angina

Chronic stable angina is a common condition with a prognosis that is less benign than is generally appreciated. The optimal treatment strategy of this disorder is unclear, and few anti-ischaemic agents have been rigorously tested in prospectively randomised mortality studies. The evidence base for the anti-ischaemic therapy of chronic angina draws upon data 'borrowed' from studies in acute coronary syndromes, and from studies in chronic angina using surrogate endpoints such as ambulatory silent ischaemia. Such evidence leads us to believe that anti-ischaemic therapy with beta-blockers offers a mortality benefit in chronic angina. In contrast, the mortality benefit of lipid lowering therapy and antiplatelet agents is well proven. Angioplasty offers no mortality benefit in the treatment of chronic angina, although it is more effective than medical therapy alone for the relief of symptoms. In a few patients with high order proximal coronary disease, coronary bypass surgery offers a distinct mortality advantage compared with medical treatment alone. Most patients, however, do not warrant such an approach, and only require surgery for when they remain symptomatic despite adequate medical therapy. Alternative strategies such as cardiac transplantation, transmyocardial laser revascularisation and spinal cord stimulation are now accepted in a subgroup of patients for the treatment of chronic angina refractory to standard therapy.

Treatment of stable angina

Severe atherosclerotic narrowing of one or more coronary arteries is responsible for myocardial ischemia and angina pectoris in most patients with stable angina pectoris. The coronary arteries of patients with stable angina also contain many nonobstructive plaques, which are prone to fissures or rupture resulting in presentation of acute coronary syndromes (unstable angina, myocardial infarction, sudden ischemic death). In addition to symptomatic relief of symptoms and an increase in angina-free walking time with antianginal drugs or revascularization procedures, the recent emphasis of treatment has been to reduce adverse clinical outcomes (coronary death and myocardial infarction). The role of smoking cessation, aspirin, treatment of elevated lipids, and treatment of high blood pressure in all patients and of beta-blockers and angiotensin-converting enzyme inhibitors in patients with diminished systolic left ventricular systolic function in reducing adverse outcomes has been well established. What is unknown, however, is whether any anti-anginal drugs (beta-blockers, long-acting nitrates, calcium channel blockers) effect adverse outcomes in patients with stable angina pectoris. Recent trials evaluated the usefulness of suppression of ambulatory ischemia in patients with stable angina pectoris, but it remains to be established whether suppression of ambulatory myocardial ischemia with antianginal agents or revascularization therapy is superior to pharmacologic therapy targeting symptom relief. Patients who have refractory angina despite optimal medical treatment and are not candidates for revascularization procedures may be candidates for newer techniques of transmyocardial revascularization, enhanced external counterpulsation, spinal cord stimulation, or sympathectomy. The usefulness of these techniques, however, needs to be confirmed in large randomized clinical trials.

Factors associated with the use of various medications amongst patients with severe coronary artery disease. SECOR/SBU Project Group

AIM

To describe variations by age, sex, symptom severity and hospital region in the use of various medications amongst patients with stable angina pectoris who are candidates for coronary revascularization.

PATIENTS

Patients (n = 2030) with chronic stable angina pectoris participating in a national survey evaluating the appropriateness of the use of percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG).

METHODS

As part of a national study of the appropriateness of coronary revascularization, data were prospectively collected on patients referred for consideration of coronary revascularization to seven of the eight public Swedish heart centres that performed approximately 92% of all bypass operations in Sweden in 1994.

RESULTS

Amongst all patients 76% were treated with beta blockers, 41% with calcium antagonists and 71% with long-acting nitrates and 70% were treated with at least two of these three drugs. Eighty-two per cent of the patients used aspirin and 14% lipid-lowering drugs. According to logistic regression analysis, with medication as the dependent variable and independent variables of age, sex, angina functional class, findings at exercise test, history of various diseases and region in Sweden where the investigation took place, the most consistent factor explaining the use of various medications was found to be geographical region. A previous history of acute myocardial infarction (AMI) was also associated with the use of all drugs and age was associated with all with the exception of beta blockers. Sex was not an independent factor explaining the use of any of the drugs.

CONCLUSION

In a national survey including patients with stable angina pectoris who are potential candidates for coronary revascularization, the most important predictor for the use of various medications was the geographical region in which the investigation took place.

Amlodipine in patients with stable angina pectoris treated with beta-blockers. Double-blind comparison with placebo

In order to assess additional anti-ischaemic effects of amlodipine (AML) on coronary artery disease (CAD) treated with beta-blockers, 32 patients with CAD, verified on angiograms, and stable angina were randomized to receive 5 mg/day of AML or placebo, increasing to 10 mg/day after 2 weeks. Baseline recording of 24-h ambulatory ECG and blood pressure, echocardiography and bicycle exercise test was repeated after treatment for 2 weeks and for 6 weeks. Reduction of ambulatory ischaemia was not significantly greater with AML than with placebo. In exercise tests the time to 0.1 mV ST segment depression and the total exercise time remained unaltered. Blood pressure was reduced by 10 mg AML. The total variability and the very low frequency component of heart rate were reduced after both doses. The clinical significance of the possible unfavourable change in autonomic modulation of the heart in CAD patients is not known.

Refractory angina pectoris in end-stage coronary artery disease: evolving therapeutic concepts

Refractory angina pectoris in coronary artery disease is defined as the persistence of severe anginal symptoms despite maximal conventional antianginal combination therapy. Further, the option to use an invasive revascularization procedure such as percutaneous coronary balloon angioplasty or aortocoronary bypass grafting must be excluded on the basis of a recent coronary angiogram. This coronary syndrome, which represents end-stage coronary artery disease, is characterized by severe coronary insufficiency but only moderately impaired left ventricular function. Almost all patients demonstrated severe coronary triple-vessel disease with diffuse coronary atherosclerosis, had had one or more myocardial infarctions, and had undergone aortocoronary bypass grafting (70% of cases). We present three new approaches with antiischemic properties: long-term intermittent urokinase therapy, transcutaneous and spinal cord electrical nerve stimulation, and transmyocardial laser revascularization.

[Conservative therapeutic approaches in terminal coronary heart disease. Chronic intermittent urokinase therapy]

Despite progress in the invasive revascularization procedures and even though conventional antianginal treatment has improved the quality of life in patients with symptomatic coronary artery disease considerably, an increasing number of patients suffers from end-stage coronary artery disease and refractory angina pectoris. For these refractory patients long-term intermittent urokinase therapy was developed as an antithrombotic intervention, which is based on its capacity to enhance thrombolysis and blood rheology, and may possibly lead to plaque regression. The coronary syndrome of refractory angina pectoris is characterized by a mismatch of severe coronary insufficiency and a relatively large amount of viable myocardium as indicated by an only moderately impaired left ventricular function. Prior to initiation of long-term intermittent urokinase therapy all potential measures to improve myocardial perfusion have to be considered in each patient. These supportive measures include rigorous reduction of LDL-cholesterol, which has proven antiischemic properties due to an improved endothelial function of epicardial conductance vessels possibly resulting in an antianginal effect. Apart from the proven antiischemic properties of long-term intermittent urokinase therapy in patients with refractory angina pectoris, objective signs of ischemic myocardial heart failure improve. Follow-up studies demonstrated a significant increase of left ventricular ejection fraction as evaluated with multi-gated blood pool analysis. Furthermore, left ventricular diastolic function normalized after a treatment period of 12 weeks. As the clinical effects last well beyond the actual treatment period and as they are accompanied by a remarkable increase in the quality of life, a complex approach as this one is justified in this highly symptomatic patient group.

Prognosis of patients with stable angina pectoris on antianginal drug therapy

Antianginal drug treatment reduces symptoms and ischemia but may also influence the prognosis of patients with stable angina pectoris. The Atenolol Silent Ischemia Study (ASIST) compared atenolol and placebo treatment (about 140 patient-years on each) in patients with mainly silent ischemia and found less aggravation of angina and a tendency toward fewer cardiac complications with atenolol treatment. The Total Ischaemic Burden European Trial (TIBET) compared slow release nifedipine, atenolol, or the combination (about 450 patient-years on each) and found no significant differences with regard to cardiac complications, a nonsignificant trend toward better prognosis on combined treatment, and more side effects on nifedipine alone compared with the other treatments. The Angina Prognosis Study in Stockholm (APSIS) compared metoprolol and verapamil (about 1,400 patient-years on each) and found similar effects on cardiovascular endpoints, tolerability, and psychosocial variables with the 2 treatments. Hypothesis-generating subgroup analyses in APSIS suggest that treatment effects may differ in hypertensive and diabetic subgroups. Beneficial effects in primary and secondary prevention, together with data from ASIST, suggest that beta 1 blockade influences prognosis favorably. The safety of short-acting nifedipine in ischemic heart disease is questioned, but TIBET data suggest that slow release nifedipine may be safe. Verapamil has beneficial effects after myocardial infarction (Danish Verapamil Infarction Trial II) and shows similar efficacy as metoprolol in the APSIS study. The paucity of placebo data (antianginal treatment cannot be withheld during long periods of time in symptomatic patients) precludes firm conclusions regarding effects of drug treatment on prognosis. It is argued that patients with stable angina pectoris do well on medical treatment, and that beta 1 blockers, verapamil, and, possibly, slow-release nifedipine may influence their prognosis favorably.

Comparison between felodipine and isosorbide mononitrate as adjunct to beta blockade in patients > 65 years of age with angina pectoris

Coronary artery disease is an increasingly common medical problem in the elderly, and relatively few studies investigating drug therapy focus on this population. To assess the efficacy and safety of the calcium channel blocker, felodipine, and isosorbide mononitrate (ISMN), as adjunct to optimal beta-blocker therapy in elderly patients, a placebo-controlled, double-blind study was conducted in 46 patients, aged between 65 and 80 years, with documented stress-induced angina pectoris and myocardial ischemia. With use of a latin-square design, with 3 periods of 4 weeks each, exercise testing was performed after each period. Felodipine, 5 mg once daily, significantly improved both time to ischemic threshold and pain threshold (p = 0.02 and p = 0.003, respectively, vs placebo), and tended to increase total exercise time (p = 0.06 vs placebo). In contrast, ISMN, 20 mg twice daily, did not significantly affect these parameters. Comparison of the 2 active treatment arms showed that, overall, felodipine was more effective than ISMN, with a statistically significant difference for time to ischemic threshold (p = 0.02). With regard to safety, felodipine was also better tolerated than ISMN, which led to more patients discontinuing study medication with ISMN (p < 0.05 between ISMN and felodipine). It is concluded that in elderly patients who are treated with optimal beta blockade, felodipine, but not ISMN, leads to an additional significant reduction in ischemic parameters during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic stable angina pectoris. Risk stratification and treatment

Workup of stable angina patients begins with careful history taking and evaluation of various risk factors, physical examination, and a resting electrocardiogram (ECG). A noninvasive exercise stress test is valuable for risk stratification. Abnormalities on a resting ECG or equivocal results on a stress test warrant an exercise test combined with thallium scintigraphy, which is more sensitive and specific. Cardiac catheterization is advisable for patients with chest discomfort and multiple risk factors, even if results of thallium testing are negative. Patients with severe or progressive angina or congestive heart failure should also have cardiac catheterization. Nitrates, beta-adrenergic blockers, and calcium channel blockers are cornerstones of medical therapy. Revascularization with coronary artery bypass graft is recommended for patients with left main coronary artery disease, left ventricular dysfunction, or severe proximal three-vessel coronary artery disease. Percutaneous transluminal coronary angioplasty (PTCA) is a good alternative for one- or two-vessel disease. Three-vessel PTCA can be accomplished, but its real role still remains to be established.

Need for invasive cardiological assessment and intervention: a ten year review

The uptake of invasive cardiological investigation and cardiopulmonary bypass procedures by the North West Surrey Health District was audited over the years 1979-88. Growth was almost continuous throughout the ten year period. The need within the district each year for coronary angiography seemed to be between 111 and 171 and for surgical revascularisation of the myocardium between 63 and 96 procedures; the first figure is the mean of the second quinquennial period (1984-88) and the second figure the total for 1988. After correction for the standardised mortality ratio and catchment area, the national requirement should lie between 690 and 1070 coronary angiograms and 390 and 600 coronary artery bypass graft operations per million population each year. There is a further national requirement for 70 valvar heart operations and 30 miscellaneous procedures per million population each year. Owing to delays in the provision of services, 20 patients died of a cardiovascular cause while they were on the waiting list for investigation or surgery. In the United Kingdom the annual target to be achieved by 1990 was 300 coronary artery bypass procedures per million population.

Efficacy of nifedipine and isosorbide mononitrate in combination with atenolol in stable angina

Many patients with angina pectoris whose symptoms are not completely controlled by beta-blockers are treated with several types of drugs, but it is not clear whether addition of a calcium-channel antagonist and/or a nitrate confers any advantage over beta-blockade alone. 18 patients receiving atenolol for stable angina pectoris completed a double-blind, randomised, crossover trial of atenolol treatment plus placebo, isosorbide mononitrate, nifedipine, and mononitrate and nifedipine (triple therapy). The patients were assessed subjectively and by treadmill exercise testing and 24 h ambulatory electrocardiographic recordings at the end of each 4-week treatment period. There were no significant differences among the treatment periods in angina attack rates, glyceryl trinitrate consumption, exercise duration to onset of angina or 1 mm ST depression, or duration of symptomless ischaemia. Total exercise duration was longer on atenolol plus mononitrate than on atenolol alone (mean difference 46 [95% confidence interval 18-88] s; p = 0.005), atenolol plus nifedipine (36 [2-71] s; p = 0.04), or triple therapy (28 [6-61] s; not significant). In 12 patients the exercise time was shorter on triple therapy than on atenolol plus mononitrate alone. Although "maximum" antianginal treatment with two or three drugs is commonly accepted, this approach confers no substantial advantage over optimum beta-blockade as monotherapy. If a second drug is needed, there is a slight advantage in favour of isosorbide mononitrate, but if this is not effective, treatment should be changed rather than added. Many patients with angina pectoris seem to be pharmacologically overtreated.

Long-term efficacy of continuous and intermittent use of transdermal nitroglycerin in stable angina pectoris

To assess efficacy of transdermal nitrate use, a randomized, placebo-controlled trial of continuous and intermittent use of nitroglycerin patches (10 mg/24 hours) was conducted in 127 patients with stable angina pectoris who discontinued exercise testing within 9 minutes because of angina. After a placebo run-in week, baseline (day 0) symptom-limited exercise testing was performed and repeated on day 1 and 14 before and after the administration of 0.5 mg of sublingual nitroglycerin. On day 0, total exercise duration was the same (within narrow limits) in all 3 groups and remained unchanged in the placebo group. On day 1, total exercise duration increased from 406 +/- 115 to 469 +/- 158 seconds (p less than 0.001) in the continuously treated group and from 396 +/- 105 to 475 +/- 171 seconds (p less than 0.001) in the intermittently treated group. In the intermittent group, exercise duration increased slightly to 483 +/- 140 seconds on day 14, and in the continuous group exercise duration decreased to 447 +/- 144 seconds. However, this decrease was not statistically significant. Similar treatment effects were seen for time to 1-mm ST depression. Sublingual nitroglycerin remained effective in all 3 groups and on all days. Eleven actively treated patients and 1 patient taking placebo discontinued the study because of headache. It is concluded that continuous use of transdermal nitroglycerin remains partially effective and intermittent therapy remains fully effective in improving long-term exercise capacity with acceptable adverse effects in patients with stable angina pectoris.

High-dose monotherapy and combination therapy with calcium channel blockers for angina. A comprehensive review of the literature

Clinical experience with the calcium channel-blocking agents has established their efficacy in the therapy of painful and silent myocardial ischemia. Questions have arisen, however, about side-effect characteristics of these medications as clinical practice has led to utilization of higher doses of individual drugs than employed in large numbers of patients in early clinical trials as well as combinations with other antianginal agents including beta-blockers. A study was undertaken to examine the published literature regarding side effects associated with high-dose versus low-dose therapy with nifedipine and diltiazem and the use of these agents in combination with beta-blockers. This investigation demonstrated that utilization of high-dose diltiazem (more than 240 mg per day) as opposed to low-dose diltiazem (no more than 240 mg per day) was associated with an increased incidence of atrioventricular block, and increased peripheral vasodilatory effects. In contrast, the use of high-dose nifedipine (more than 60 mg per day) was not associated with atrioventricular block. At clinically high dosage levels, the incidence of peripheral edema was comparable for both nifedipine and diltiazem, although low-dose nifedipine resulted in a significantly greater incidence of edema compared with low-dose diltiazem. This analysis also demonstrated that bradyarrhythmia is associated with the combination of a beta-blocking agent and either low- or high-dose diltiazem, but not with nifedipine-beta-blocker combinations. Clinical experience suggests caution in the combined use of diltiazem and a beta-blocking agent because of the demonstrated additional adverse negative chronotropic and dromotropic effects. No additional adverse electrophysiologic effects have been noted for nifedipine-beta-blocker combinations. The literature analysis supports and mirrors widespread clinical experience obtained since nifedipine and diltiazem were introduced. It should be noted, though, that combination therapy with calcium channel blockers and beta-blockers should be done with caution, since there have been occasional reports of congestive heart failure or exacerbation of angina with this combination.

The efficacy of the addition of nifedipine in patients with mixed angina compared to patients with classic exertional angina: a multicenter, randomized, double-blind, placebo-controlled clinical trial

Episodes of myocardial ischemia in patients with coronary artery disease may be due to transient increases in coronary vasomotor tone superimposed on a fixed atherosclerotic obstruction. The purpose of this study was to determine whether identification of the clinical pattern of angina could predict the therapeutic response to the addition of nifedipine to a regimen of beta blockers and/or long-acting nitrates. Seventy-two patients with stable exertional angina were divided into two groups: "classic exertional angina" (17 patients), defined as exertional angina with a stable threshold; and "mixed angina" (55 patients), defined as exertional angina provoked by a variable threshold and/or at least two episodes of rest angina within the 3 months prior to screening. Patients were studied with nifedipine and placebo in a 6-week, double-blind, crossover design that used serial anginal diaries, exercise treadmill tests, and 24-hour ambulatory ECG monitoring. In patients with mixed angina, nifedipine reduced the frequency of angina compared to that during placebo treatment (13.1 vs 9.9 episodes/3 weeks, p less than 0.01) and reduced nitroglycerin consumption (11.7 vs 7.5 tablets/3 weeks, p less than 0.05); while in patients with classic exertional angina, nifedipine had no symptomatic effect (7.9 vs 6.8 anginal episodes/3 weeks, NS; 6.4 vs 5.8 nitroglycerin tablets/3 weeks, NS). Patients in both groups experienced a significant decrease in the manifestations of ischemia during exercise testing. Patients with mixed angina experienced a reduction in the daily frequency of painful episodes of ST segment depression during nifedipine treatment compared to placebo (0.6 vs 0.2 episodes, p less than 0.05), but there was no effect on the frequency of episodes of silent ischemia (4.2 vs 3.4 episodes, NS). In patients with classic exertional angina, the addition of nifedipine had no effect on any measure of ambulatory ischemia. We conclude that patients with mixed angina are more likely to benefit symptomatically from the addition of nifedipine therapy than patients with classic exertional angina. The lack of a consistently preferential response to nifedipine in patients with mixed angina, however, suggests that episodic coronary vasoconstriction may not be the only mechanism responsible for ischemia in these patients, and/or that nifedipine may not necessarily provide additional therapeutic benefit beyond that conferred by a regimen of beta blockers and/or nitrates.

The role of nitrates, beta blockers, and calcium antagonists in stable angina pectoris

Numerous controlled studies have shown that nitrates, beta blockers, and calcium antagonists are effective in the treatment of stable angina pectoris. The pharmacokinetics, pharmacodynamics, and hemodynamic effects of these agents are different, and thus combination therapy offers additive improvement and also counterbalancing of the undesirable side effects of each drug. The choice of therapy depends on the severity of symptoms, associated diseases, compliance, side effects, and status of left ventricular function. The main mechanism of improvement is a decrease in myocardial oxygen consumption, though an increase in coronary blood flow is another potential reason for the use of calcium blockers. This review considers the properties of these drugs, their mechanism of action, and the results of randomized studies.

Calcium channel antagonists. Part IV: Side effects and contraindications drug interactions and combinations

With the correct selection of drug and patient, the calcium antagonists as a group can be remarkably effective at relatively low cost of serious side effects. Almost all side effects are dose related. Minor side effects include those caused by vasodilation (flushing and headaches), constipation (verapamil), and ankle edema. Serious side effects are rare and result from improper use of these agents, as when intravenous verapamil (or diltiazem) is given to patients with sinus or atrioventricular nodal depression from drugs or disease, or nifedipine to patients with aortic stenosis. The potential of a marked negative inotropic effect is usually offset by afterload reduction, especially in the case of nifedipine which actually has the most marked negative inotropic effect. Yet caution is required when even calcium antagonists, especially verapamil, are given to patients with myocardial failure unless caused by hypertensive heart disease. Drug interactions of calcium antagonists occur with other cardiovascular agents such as alpha-adrenergic blockers, beta-adrenergic blockers, digoxin, quinidine, and disopyramide. The most marked interaction with digoxin is that with verapamil, which may raise digoxin levels by over 50%. Combination therapy of calcium antagonists with beta-blockers is increasingly common, and is probably safest in the case of dihydropyridines. Other combinations being explored are those with angiotensin-converting enzyme inhibitors and diuretics.

The combination of antianginal drugs: effects and indications

Today, three classes of drugs, all acting differently on the myocardium, the coronary circulation, and the peripheral circulation, that is, on the determinants for myocardial oxygen consumption (heart rate, contractility, and wall tension), are at the physician's disposition for anti-ischemic medical treatment: nitrates, beta-receptor blocking agents and Ca antagonists. All three drugs have been proven to exhibit a marked antianginal effect when given alone, as demonstrated both by an improvement in exercise performance as well as in perfusion and a significant decrease in symptomatic and silent ischemic episodes. Treatment should cover the total ischemic burden, which can be assessed today more accurately by Holter monitoring than with exercise tests alone. It has been shown in patients with stable angina that the majority of ischemic episodes are silent (over 75%); therefore, the question arose as to whether medical anti-ischemic treatment should aim at the prevention not only of symptomatic, but also of silent episodes. Furthermore, ischemia was revealed to be not only a marker for the presence of high-grade life-threatening obstructions, but also to have prognostic implications, not only in symptomatic, but also in asymptomatic episodes. In addition, ischemia can lead to life-threatening arrhythmia and irreversible myocardial damage, especially localized fibrosis. To what extent this is prevented by vigorous anti-ischemic treatment is still unanswered; however, as pathophysiologically symptomatic and asymptomatic ischemic episodes behave similarly, the latter should be included in treatment. The combinations of drugs, especially of nitrates and beta blockers, Ca antagonists and beta blockers, and also nitrates and Ca antagonists result in a further improvement in exercise performance and a reduction in ischemic episodes, allow the dose to be reduced, and minimize side effects. In addition, as is indicated from their hemodynamics, in special clinical situations, combinations might be preferable. Whether treatment should primarily reduce sympathetic drive or, rather, be directed towards vasodilation depends on the type of angina and the individual need. Hence, combining drugs in treating angina pectoris represents a true therapeutic challenge for the physician.

Comparison of nifedipine and isosorbide dinitrate when added to maximal propranolol therapy in stable angina pectoris

A study was performed to compare isosorbide dinitrate and nifedipine as adjunctive therapy in 14 patients with coronary artery disease and stable angina pectoris taking maximal beta-blocking drugs. Drug titration phases ensured maximal therapy of propranolol, isosorbide or nifedipine. The combination of nifedipine and propranolol was more effective than the combination of isosorbide and propranolol in reducing angina and increasing exercise capacity (323 vs 416 seconds, p less than 0.005) during exercise treadmill testing. Nifedipine produced a greater reduction in systolic blood pressure at submaximal exercise than isosorbide. Global and regional ejection fraction at rest and exercise was assessed with radionuclide ventriculography. The substitution of nifedipine for isosorbide depressed the global ejection fraction at rest (0.61 to 0.56 p less than 0.05) and produced a slight improvement in exercise ejection fraction (0.47 to 0.51, difference not significant). The decrease in ejection fraction from rest to exercise was 0.14 to 0.04 with nifedipine (p less than 0.005). The benefit of nifedipine compared with isosorbide occurred in regions with marked exercise-induced ischemia. In patients treated with maximal beta-blocking therapy, nifedipine is an effective alternative to isosorbide as a combination agent with propranolol. The salutary effects of nifedipine included afterload reduction with exercise and possible improvements in coronary blood supply.

The need for invasive cardiological assessment and operation: viewpoint of a district general hospital

The uptake of cardiac catheterisation and operation and of permanent pacemaker implantation in a district hospital in Surrey from 1979 to 1984 was studied prospectively. The 1982-84 figures for coronary artery operation indicated that 362 procedures/million population/annum were needed in the district. If patients with greater than or equal to New York Heart Association grade II angina only received operation the corresponding figure would have been 325. The national need for these procedures (464/million population/year) was estimated by correcting for the low standardised mortality ratio for ischaemic heart disease in the health district that was studied. Valvular heart disease accounted for 79 operations/million population/annum and permanent pacemaker insertion for 87 procedures/million population/annum. These figures underline the substantial shortfall in modern cardiac care in the United Kingdom.

Problems associated with clinical evaluation of antianginal medications

Assessing the efficacy of antianginal medications is not as easy as it might first appear. Many factors, including the protocol, the subjects chosen for study and the physicians conducting the trial, may produce study bias and thereby yield equivocal results. Objectively attempting to quantitate a subjective event such as angina inherently poses many difficulties. The variable nature of anginal episodes makes identification of attacks, or conversely, elimination of such attacks, difficult to assess. In terms of the protocol, it is necessary to determine what indexes will be used as criteria of efficacy, what doses, either standard or maximally tolerated, will be used for study and what measures will be taken to nullify placebo effect. In terms of patient selection, the varying methods of confirming the diagnosis of ischemia and the questions of concurrent illness, compliance and life-style alterations are all factors that can make findings difficult to elucidate. Finally, investigator bias may be introduced into study results because of prestudy prejudice, involvement in data acquisition and interpretation of findings. It is unlikely that any investigator or group of investigators will ever produce a protocol applicable to all types of antianginal medications that will be universally convincing. Conclusions regarding the efficacy of any antianginal medication will undoubtedly continue to be predicated on assessments made by independent investigators using a variety of research protocols, none of which is likely to be perfect.

Double-blind crossover comparison of the antianginal effects of nifedipine and isosorbide dinitrate in patients with exertional angina receiving propranolol

A double-blind crossover study was performed on 27 patients with proved fixed coronary artery disease and stable angina pectoris. The study was designed to compare the relative efficacy of two combination therapies, nifedipine plus propranolol and isosorbide dinitrate plus propranolol, in terms of antianginal response and effect on exercise tolerance by evaluation of treadmill testing. The combination of nifedipine and propranolol was superior to the combination of isosorbide and propranolol in reducing the number of anginal attacks (p = 0.03), increasing total exercise time (p less than 0.02), increasing oxygen consumption achieved at end of exercise (p less than 0.03), increasing time to onset of pain (p = 0.003) and increasing oxygen consumption achieved at onset of pain (p = 0.003). Analysis of the rate-pressure products suggests that the difference in these results may be explained by the greater effect of nifedipine on afterload reduction. Although nitroglycerin consumption was reduced from baseline levels during combination nifedipine therapy (p less than 0.001), there was no statistical difference between nifedipine combination therapy and isosorbide combination therapy. In conclusion, although both combination therapies were superior to propranolol therapy alone, the combination of nifedipine and propranolol was more effective than the combination of isosorbide and propranolol in reducing the incidence of angina and improving exercise performance. Side effects were experienced at a similar frequency during both combination therapies.

Addition of nifedipine to maximal beta-blocker-nitrate therapy: effects on exercise capacity and global left ventricular performance at rest and during exercise

Nifedipine is a potent coronary vasodilator in the resting state and an effective afterload-reducing agent. This study was undertaken because of the concern that the addition of nifedipine to beta-blocker therapy could produce serious untoward hemodynamic consequences. Although this combination is usually well tolerated, occasional reports suggest that the combination of nifedipine and beta-blocking agents may increase the likelihood of congestive heart failure, severe hypotension or exacerbation of angina. Further, there is a need to know if the addition of nifedipine to therapy with maximally tolerated doses of long-acting nitrates and beta blockers would provide further symptomatic relief without excessive adverse effects. Finally, the effect of adjunctive nifedipine on global left ventricular performance at rest and during exercise was examined. Sixteen patients, all of whom had 3 or more episodes per week of angina pectoris despite therapy with long-acting nitrates and beta blockers, were selected. Radionuclide ventriculography was performed at rest and during exercise; global ejection fractions (EFs) were determined by manually tracing the left ventricular end-diastolic perimeter with an electronic cursor. In the first phase, beta blockers and nitrates were used; in the second phase nifedipine, 10 mg every 6 hours, was added and titrated to reduce systolic blood pressure at rest by at least 10 mm Hg or until intolerable adverse effects occurred. When nifedipine was added to therapy, the difference between global EF at rest and during exercise was reduced from - 0.15 to + 0.02 (p less than 0.00001); exercise duration was increased from 431 seconds to 532 (p less than 0.001), with only 8 patients limited by angina, compared with 16 during the initial therapy.(ABSTRACT TRUNCATED AT 250 WORDS)