Metoprolol, nifedipine, and the combination in stable effort angina pectoris

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.

Efficacy of monotherapy compared with combined antianginal drugs in the treatment of chronic stable angina pectoris: a meta-analysis

OBJECTIVE

To determine the relative efficacy of antianginal drugs administered as monotherapy or in combination in patients with chronic stable angina.

METHODS

A meta-analysis was performed on randomized trials, published in English between 1980 and 1999, that directly compared combined treatment and monotherapy. Twenty-two articles were included, all on the comparison of -blocker monotherapies to their combination with a calcium antagonist and 10 on the comparison of calcium antagonist monotherapies to their combination with a -blocker.

RESULTS

Time to 1 mm ST-segment depression, total exercise duration and time to onset of anginal pain were significantly increased with the combined therapy compared to -blocker alone (by 8, 5 and 12%, respectively). Only time to 1 mm ST-segment depression was significantly increased with the combined therapy compared to calcium antagonist alone (by 9%). For all these parameters, the adjusted differences were significant only within 6 h following drug intake and were not significant after 6 h. No analysis of safety data could be performed.

CONCLUSION

As far as exercise testing is concerned, the combination of a calcium antagonist and a -blocker is statistically more effective than either monotherapy. Further studies are needed to confirm the higher efficacy after the first 6 h following drug intake.

Evidence-based guideline for the primary care management of stable angina

This is an updated version of the first North of England Stable Angina Guideline (1,2) and summarizes the full guideline. (3) This paper presents all the recommendations within the guideline; and where these are new or substantially altered from the original version, it also presents a summary of the supporting evidence. The aims and methods of development (summarized in Box 1) of this guideline are unchanged from the original version, to which readers are directed for more detail. The research questions raised during the development of this guideline are shown in Box 2.

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.

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.

Comparison of the efficacy of atenolol and its combination with slow-release nifedipine in chronic stable angina

There is still uncertainty of whether combined therapy with a beta-blocker and calcium-channel antagonist provides additive or synergistic clinical benefits in most patients with stable angina pectoris. The comparative antianginal effect of atenolol 50 mg and atenolol 50 mg and slow release nifedipine (20 mg) twice a day was assessed in 27 patients with chronic stable angina in a randomized, double-blind, crossover study. After a 4 week run-in period on atenolol, patients were randomly allocated to receive either atenolol alone or its combination with nifedipine and then crossed over to the alternative treatment for a further 4 weeks. Symptom-limited exercise treadmill tests were performed according to the Naughton protocol. The major endpoints in this study were (a) exercise time to pain; (b) exercise time to > or = 1 mm ST depression; (c) total exercise time; (d) maximal ST-segment depression; (e) number of anginal attacks; and (f) nitrate consumption. The preexercise systolic blood pressure was lower on the combination treatment than on atenolol alone, but heart rate was lower on atenolol compared with the combination treatment. There was no difference in the systolic blood pressure at the onset of pain or at 1 mm ST depression, while heart rate was lower on both occasions with atenolol compared to the combination treatment. There was no difference between the two treatments in terms of the rate-pressure product at the onset of pain or at 1 mm ST depression. Twice as many patients experienced pain later with the combination treatment than with atenolol alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient myocardial ischemia during nifedipine therapy in stable angina pectoris, and its relation to coronary collateral flow and comparison with metoprolol

There are conflicting results concerning the anti-ischemic effect of nifedipine in patients with chronic stable angina. Therefore, the purpose of this study was to assess whether the anti-ischemic effect of nifedipine may be related to coronary collateral circulation. Forty-one patients with stable angina and coronary artery disease were randomized to a parallel double-blind study with nifedipine and metoprolol, and compared for effects on transient ischemic episodes during ambulatory electrocardiographic monitoring and exercise-induced ischemia. The effects were correlated to the presence of collateral circulation. In 17 patients, angiographically poor or no collateral flow was observed (group 1), and 24 had good collateral flow (group 2). Nifedipine was administered to 20 patients (8 in group 1, and 12 in group 2). In group 1, nifedipine reduced the frequency of total and asymptomatic ischemic episodes (p < 0.05), whereas significant increases in both total (p < 0.05) and silent (p < 0.01) ischemia were observed in group 2. Exercise variables were slightly improved (p = NS) during nifedipine therapy in group 1, and slightly worsened (p = NS) in group 2. Reflex tachycardia was not observed at either the onset of transient ischemia out of the hospital or exercise-induced ischemia. This was in contrast with the effect in 21 patients treated with metoprolol (9 in group 1, and 12 in group 2) where significant reductions were observed in the frequency of both total (p < 0.01) and silent (p < 0.01) ischemia in both groups. Furthermore, a beneficial effect was observed on all exercise variables.(ABSTRACT TRUNCATED AT 250 WORDS)

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

Seventy-four patients with chronic stable mild angina, mild coronary artery disease (83% had one- or two-vessel disease) and normal left ventricular function were studied to measure the response of treadmill exercise performance and painful and silent ischemia in the ambulatory setting to randomly assigned treatment with nifedipine or propranolol and their combination; titration to maximal tolerated dosages was performed in double-blind manner. At 3 months both nifedipine and propranolol reduced the weekly angina rate (p less than 0.05); during treadmill exercise testing, increases (p less than 0.05) were noted in time to angina and total exercise time and decreases in maximal ST depression at the end of exercise. There were no differences between the responses to nifedipine and propranolol and no significant additional changes were seen after another 3 months of therapy. The combination of nifedipine and propranolol reduced the number of patients with angina on exercise treadmill testing from 64% to 38% (p less than 0.05). During ambulatory electrocardiographic monitoring before treatment, there were 1.4 +/- 2.4 (mean +/- SD) episodes/24 h of painful ischemia and a very low silent ischemia frequency: mean 1.1 +/- 2.7 episodes/24 h, mean duration 16 +/- 25 min/24 h. Treatment with propranolol and nifedipine resulted in reduction of episodes and duration of painful and painless ischemia; approximately 77% of patients were free of all ischemic episodes. It is concluded that patients with chronic stable mild angina have a low incidence of silent ischemia. Nifedipine or propranolol alone, titrated to individualized maximally tolerated dosages, are equally effective in long-term control of painful and painless ischemia, anginal episodes and exercise-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Paradoxical effect of long-term treatment of nifedipine on total ischemic load in patients with stable angina pectoris

In 50 patients with stable effort angina the effect of three drugs, metoprolol, nifedipine, and diltiazem was assessed by analyzing exercise stress test response and ambulatory ECG recordings. Both metoprolol and diltiazem caused a significant increase in time to ischemic threshold during exercise and a significant decrease of maximum ST-segment depression (during exercise and ambulatory ECG monitoring) and in the average number of daily ischemic episodes. Only metoprolol significantly reduced heart rate and rate-pressure product at the ischemic threshold during exercise. In the group of patients treated with nifedipine no significant improvement was observed in exercise tolerance or in number of ischemic episodes/24 h. Moreover, the subset of nonresponders in the two methods was larger than in the other two groups. In some of these patients a clearcut worsening of total ischemic load was observed, despite the control of symptoms. This adverse effect might be attributed to the different consequences of the vasodilatory effect of nifedipine on blood flow through stenosed vessels.

Myocardial ischemia during daily activities: the importance of increased myocardial oxygen demand

The role of increased myocardial oxygen demand in the pathophysiology of myocardial ischemia occurring during daily activities was evaluated in 50 patients with coronary artery disease and exercise-induced ST segment depression. Each patient underwent ambulatory electrocardiographic (ECG) monitoring for ST segment shifts during normal daily activities and symptom-limited bicycle exercise testing with continuous ECG monitoring. All 50 patients had ST depression greater than or equal to 0.1 mV during exercise. A total of 241 episodes of ST depression were noted in the ambulatory setting in 31 patients; only 6% of these were accompanied by angina pectoris. Significant (0.1 mV) ST depression during ambulatory monitoring was preceded by a mean increase in heart rate of 27 +/- 12 beats/min. Patients with ischemia during daily activities developed ST depression earlier during exercise (7.9 +/- 4.4 vs. 14.2 +/- 6.4 min, p less than 0.001) and tended to have significant ECG changes at a lower exercise heart rate and rate-pressure product than did those without ST depression during ambulatory monitoring. In the 31 patients with ischemia during daily activities, the mean heart rate associated with ST depression in the ambulatory setting was closely correlated with the heart rate precipitating ECG changes during exercise testing (r = 0.74, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the antianginal effect of nifedipine: influence of formulation dependent pharmacokinetics

Nifedipine capsules t.d.s. and an extended release formulation of nifedipine, nifedipine-ER tablets, given once daily in corresponding daily doses, have been compared with placebo in a double-blind, three-way cross-over study in 24 patients with stable angina pectoris. The objective was to study the influence on the antianginal effect of the different pharmacokinetics of several preparations of nifedipine. All patients received concomitant treatment with beta-adrenoceptor blockers. Antianginal efficacy was assessed by a dynamic exercise test at the end of the dosage intervals, i.e. 8 and 24 h after nifedipine capsules and nifedipine-ER, respectively, as well as 6 h after dosing. Six h after dosing the time of onset of chest pain and total exercise time were longer and total work was significantly higher during both nifedipine-ER (plasma concentration 260 nmol/l) and placebo treatment than after nifedipine capsules (plasma concentration 78 nmol/l). Time to 1 mm ST depression was longer during nifedipine-ER than during nifedipine capsule treatment. No significant difference was seen between nifedipine-ER and placebo. At the end of the dosage interval (24 and 8 h after nifedipine-ER and nifedipine capsules, respectively), no significant difference was found between nifedipine-ER (plasma concentration 75 nmol/l) and the other two treatments. However, placebo was superior to nifedipine capsules (plasma concentration 58 nmol/l) both in the time to onset of chest pain and total exercise time. The lack of effect at the end of the dosage interval was probably due to the subtherapeutic plasma nifedipine level.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of dihydropyridine and phenylalkylamine calcium antagonists in patients with coronary heart disease

To evaluate possible differences between dihydropyridine and phenylalkylamine calcium antagonists in the setting of chronic stable angina, 2 placebo-controlled, double-blind, crossover trials were conducted comparing the effects of gallopamil and nifedipine on exercise tolerance and ischaemic ST depression, using standard as well as slow release formulations. In the first study, 30 patients received standard formulations of gallopamil (50mg 3 times daily) and nifedipine (20mg 3 times daily). This trial was stopped after 9 patients had been enrolled, because of severe exacerbation of angina in 3 nifedipine recipients. 21 patients then entered a second protocol in which the nifedipine dose was reduced to 10mg 3 times daily. Compared with the preceding placebo periods, time to angina onset and total exercise time were statistically significantly (p less than 0.01) prolonged by gallopamil (by 30 and 18%, respectively), and nonsignificantly prolonged by nifedipine (by 20 and 13%, respectively), after 4 weeks' treatment. Increases in heart rate and rate-pressure product at maximal comparable workloads were less with gallopamil than with nifedipine (p less than 0.01). In contrast to nifedipine, gallopamil was associated with very few side effects. The second trial comprised 24 patients who received slow release formulations of gallopamil (100mg twice daily) and nifedipine (20mg twice daily) over 2 weeks. Again, both drugs exhibited significant anti-ischaemic efficacy, as evidenced by reductions in ST depression at maximal comparable workloads and increases in exercise time compared with placebo, but the differences between the treatments were not statistically significant. Side effects were more frequent with nifedipine, but less severe than with the standard formulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian variation of heart rate is affected by environment: a study of continuous electrocardiographic monitoring in members of a symphony orchestra

Twenty four hour ambulatory ST segment monitoring was performed on 48 members (43 players and five members of the management/technical team) of the British Broadcasting Corporation (BBC) symphony orchestra without a history of cardiac disease. This period included final rehearsals and live performances (for audience and radio) of music by Richard Strauss and Mozart at the Royal Festival Hall (n = 36) and Rachmaninov and Tchaikovsky at the Barbican Arts Centre (n = 21). During the period of monitoring one person (2%) had transient ST segment changes. Mean heart rates were significantly higher during the live performances than during the rehearsals. Mean heart rates during the live performance of Rachmaninov and Tchaikovsky were significantly higher than during Strauss and Mozart in those (n = 6) who were monitored on both occasions. Mean heart rates in the management and technical team were higher than those of the players. The recognised circadian pattern of heart rate, with a peak in the morning waking hours, was altered similarly during both concert days, with a primary peak occurring in the evening hours and a lesser peak in the morning for both musicians and management/technical staff. This study showed that environmental factors are of primary importance in defining the circadian pattern of heart rate. This has important implications when identifying peak periods of cardiovascular stress and tailoring drug treatment for patients with angina pectoris.

The combination of slow-release nifedipine and atenolol for stable angina

Beta-adrenoceptor antagonists, such as atenolol and the dihydropyridine calcium antagonist nifedipine, have antianginal actions that should prove complementary when the drugs are used in combination. Atenolol acts primarily by reducing myocardial oxygen demand, while the vasodilator effects of nifedipine can both reduce demand and increase oxygen supply. The slow-release tablet formulation of nifedipine (Nifedipine Retard) provides more persistent plasma concentrations than the conventional capsule formulation, which may prolong the duration of action. There is increasing evidence that the plasma nifedipine concentration is closely related to efficacy, although the absolute concentration required to improve exercise tolerance in patients with angina varies between individuals. Clinical studies indicate that for many patients the duration of action of slow-release nifedipine, particularly when added to atenolol, is less than 12 hours. This reflects the extensive but variable first-pass metabolism of nifedipine, leading to subtherapeutic trough concentrations. To achieve 24-hour symptom relief, slow-release nifedipine will often need to be given three times daily to patients with angina.

Ischemia in the ambulatory setting--the total ischemic burden: relation to exercise testing and investigative and therapeutic implications

To establish the relation between treadmill exercise testing and ambulatory St segment monitoring in the detection of ischemia in patients with coronary artery disease, and to assess whether standard medical therapy affects any such relation, 277 patients with stable angina and angiographically documented coronary artery disease were studied with treadmill exercise testing and 48 h ambulatory ST segment monitoring. One hundred forty-six patients (52%) were studied while receiving no routine antianginal therapy, and 131 (48%) while receiving standard medical therapy. In 187 patients (67%) the exercise test was positive for ischemia. During 11,964 h of ambulatory monitoring, 881 episodes of ischemia (645 [73%] silent) were recorded, of which 809 (92%) occurred in patients with a positive exercise test. The mean heart rate at the onset of ischemic episodes during ambulatory monitoring was significantly less than that at the onset of 1 mm ST segment depression during exercise testing (94.5 versus 105.9 beats/min, p less than 0.0001). However, the frequency of ambulatory ischemic episodes was strongly related to a positive exercise test (p less than 0.001), and this relation was similar for both silent and painful ischemia (p less than 0.0001 for both) and in patients who were and were not receiving therapy (p less than 0.0001 for both). The total duration of ischemia was similarly related to a positive exercise test (p less than 0.0001). Only one patient with a negative exercise test had frequent (greater than 5/day) episodes of ischemia on ambulatory monitoring and had documented coronary artery spasm. Thus, exercise testing identifies the majority of patients likely to have significant ischemia during their daily activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Complementary mechanisms of atenolol and diltiazem in the clinical improvement of patients with stable angina

The combination of atenolol with diltiazem has been shown to be useful in the treatment of patients with coronary artery disease. Eighteen patients with proven coronary artery disease, stable angina, and no previous myocardial infarction were studied before and after treatment with atenolol (100 mg/day) (9 patients) or diltiazem (180 mg/day) (9 patients). Ischemic threshold at stress test, pressure-rate product at ischemic threshold, direct oxygen consumption at ischemic threshold, and exercise ejection fraction were determined. There was a slight increase in the duration of exercise, maximal oxygen consumption, and ischemic threshold after treatment with each drug. Double product at ischemic threshold decreased from 20.9 to 19.8 (p = NS) with atenolol but increased from 20.1 to 21.9 (p = NS) with diltiazem. Conversely oxygen consumption at ischemic threshold increased with atenolol to nearly significant values from 17.2 to 23.6 (p = 0.067) but not with diltiazem (16.2 to 22.3; p = 0.16). Before treatment, exercise ejection fraction increased less than 10% or decreased from its resting values in all patients but 1 with atenolol and 1 with diltiazem, but exercise ejection fraction increased significantly after treatment with atenolol (60.6 to 67.5; p = 0.02) but not with diltiazem. This improvement was due to a significant reduction in end systolic volume (103.8 to 78.6; p = 0.019), despite a similar increase in heart rate and blood pressure in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium channel antagonism and beta blockade in combination--a therapeutic alternative in cardiovascular disorders. A review

Calcium-channel antagonists and beta-adrenergic blocking agents have become important modalities in the cardiovascular therapeutic armamentarium. These drugs are often administered as monotherapy to a wide range of cardiological patients with angina pectoris, hypertension, arrhythmias, congestive heart failure, and other diseases. Since within each class these drugs exhibit pharmacologic differences, it follows that their effectiveness varies in different disease states and that they exhibit a wide variety of side effects. In an attempt to optimize therapy, the individual drugs from these two classes can be combined; and the efficaciousness and side-effect profile of various combinations between calcium-channel antagonists and beta blockers are discussed in this review. Recommendations as to which patients may benefit from a combination and as to which patients may be harmed by the combination therapy will be made. Very few studies have compared the safety and efficacy of a single agent with the combination and with placebo in a controlled randomized fashion. To determine which therapy is superior and to determine which combination one should recommend under what circumstances, such placebo-controlled, randomized trials are a necessity, and will hopefully be performed although the complexity is enormous.

Beta-adrenoceptor antagonists plus nifedipine in the treatment of chronic stable angina pectoris

The antianginal effects of beta-adrenoceptor antagonists are achieved by a reduction in myocardial oxygen demand. This is a rational approach to treatment in patients whose angina is caused by a fixed stenosis. However, dynamic coronary vasospasm is an important factor in patients with chronic stable angina. Nifedipine increases myocardial oxygen supply by reducing coronary vascular tone and is a logical approach to treatment in these patients. For monotherapy of angina, nifedipine is less effective than the beta-adrenoceptor antagonists, but the combination has additive effects in reducing the frequency of anginal episodes and improving exercise tolerance. Plasma concentrations of nifedipine are closely related to clinical efficacy, and the variable first-pass metabolism of the drug leads to wide interindividual differences in peak concentrations and duration of action. Increasing the size of individual doses of nifedipine carries a risk of enhanced side effects due to high peak plasma concentrations. Optimal treatment may be more appropriately achieved in some patients by a slow release formulation, but with an increased frequency of administration.

Comparison of antianginal efficacies and exercise hemodynamic effects of nifedipine and diltiazem in stable angina pectoris

The antianginal efficacies of nifedipine (40 to 120 mg/day) and diltiazem (120 to 360 mg/day) were studied in 21 normotensive patients with chronic stable angina pectoris, using a randomized, double-blind, crossover design. Patients received each agent titrated to maximum tolerated doses for 6 weeks, after a 2-week placebo baseline period. The maximum tolerated dose for nifedipine was 72 +/- 8 (standard error) mg/day and for diltiazem 297 +/- 20 mg/day. Two patients discontinued nifedipine early because of side effects. Duration of symptom-limited treadmill exercise was longer during the nifedipine (556 +/- 43 seconds) and diltiazem periods (546 +/- 39 seconds) compared with placebo baseline (474 +/- 41 seconds, p less than 0.02). Compared with placebo, nifedipine caused a significant increase in heart rate both at rest standing and at peak exercise. Nifedipine decreased resting systolic blood pressure but had no effect at peak exercise. In contrast, diltiazem caused a significant decrease in heart rate at rest but had no effect on blood pressure at rest or at peak exercise. Thus, nifedipine and diltiazem have differential effects on heart rate and systolic blood pressure suggesting different modes of action. However, despite the increase in exercise duration, neither nifedipine nor diltiazem increased the heart rate-systolic pressure product during maximum exercise. This suggests that the antianginal effects of the 2 agents probably are mediated via reduction of myocardial oxygen demand at submaximal exercise. In addition, diltiazem appears to be better tolerated than nifedipine.

Different vasomotor action of nifedipine on dynamic coronary obstructions and therapeutic response in effort and prinzmetal angina

Variations induced by nifedipine (10 mg sublingually) in the residual lumen diameter of significant (greater than 50%) coronary lesions were assessed angiographically in 58 patients with effort angina (group 1) and in 19 patients with Prinzmetal angina (group 2). A relationship was sought between these acute variations of the stenotic lumen and the clinical response to treatment with the same drug (20 mg four times daily). Treatment efficacy was evaluated with exercise testing in group 1 and Holter monitoring in group 2. In group 1 the residual segment of stenotic diameter showed an increase, decrease, or no change with the calcium antagonist. Nifedipine failed to improve 40% of the cases (21% unchanged and 19% worsened) in group 1. In the same group of patients, the responses to exercise tests were dissociated from the acute vasomotor pattern. Changes in the pressure-rate product also did not explain the clinical results. In group 2 the majority of lesions had compliant portions, which invariably reacted to nifedipine with dilatation. All patients with the Prinzmetal form had relief of the anginal episodes with treatment. These data suggest that the therapeutic efficacy of nifedipine in classic effort angina probably is the net result of influences on the myocardial oxygen consumption and supply, and the acute coronary vasomotor pattern does not allow to predict the clinical response. Stenotic lesions in the Prinzmetal form possess a distinct sensitivity to the relaxant action of calcium channel blockade, which reasonably explains the highly positive response to treatment.

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.

Comparison of combination nifedipine-propranolol and diltiazem-propranolol with high dose diltiazem monotherapy for stable angina pectoris

Patients with chronic stable angina are frequently treated with calcium antagonist-beta-blocker combination drug therapy. However, there is a paucity of data comparing such combination therapies with each other and with high dose calcium antagonist monotherapy. Nineteen patients with chronic stable angina pectoris were studied using a prospective, randomized, Latin-square crossover protocol in an effort to determine the differential effects of nifedipine-propranolol combination therapy, diltiazem-propranolol combination therapy and high dose diltiazem monotherapy on exercise treadmill performance. All patients performed exercise tolerance tests after 4 weeks on each of the 3 therapeutic regimens. Both nifedipine (mean daily dose 70 +/- 23 mg) and diltiazem (mean daily dose 237 +/- 12 mg) in combination with propranolol (mean daily dose 146 +/- 58 mg) resulted in significant increases in total exercise time, time to onset of angina and time to maximal ST-segment depression compared with high dose diltiazem (mean daily dose 347 +/- 38 mg) monotherapy (p less than or equal to 0.001). Double-product at rest and the increase observed from rest to the end of stage 1 were significantly decreased during nifedipine-propranolol and diltiazem-propranolol combination therapy compared with high dose diltiazem monotherapy (p less than or equal to 0.001). In patients with chronic stable angina both nifedipine-propranolol and diltiazem-propranolol combination therapy resulted in significantly greater improvement in exercise performance compared with high dose diltiazem monotherapy.

Randomized double-blind comparison of metoprolol, nifedipine, and their combination in chronic stable angina: effects on total ischemic activity and heart rate at onset of ischemia

In a randomized double-blind study, treatment with either metoprolol, nifedipine, or their combination was compared for effects on ischemic variables and heart rate obtained during ambulatory monitoring in 42 patients with chronic stable angina. All patients had severe chronic stable angina of at least 6 months' duration despite medical treatment, and exhibited coronary artery stenosis of 75% in one or more coronary arteries. Metoprolol reduced the frequency of total (p less than 0.01) and asymptomatic ischemic episodes (p less than 0.05), the duration of ischemia (p less than 0.05), and the ischemic burden (p less than 0.05), which contrasted to the lack of any similar significant effect during nifedipine monotherapy. During combination therapy, there was a tendency to further improvement, which did not reach statistical significance compared with metoprolol monotherapy. Heart rate at the onset of ischemia was reduced by metoprolol therapy (p less than 0.01), indicating that metoprolol acts by reducing myocardial oxygen demand even during ischemic episodes observed in daily life, where impairments of myocardial oxygen supply are suspected. No change in heart rate at the onset of ischemia could be detected during nifedipine monotherapy. It is concluded that metoprolol monotherapy, as well as its combination with nifedipine, effectively reduces total ischemic activity compared with placebo and nifedipine monotherapy. Control of ischemic activity in chronic stable angina may have prognostic implications.

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.

Nadolol versus diltiazem and combination for preventing exercise-induced ischemia in severe angina pectoris

Combination beta-blocker and calcium antagonist therapy has been shown to be superior to monotherapy with either class of drugs in the treatment of patients with severe angina pectoris. Some combinations of these agents have resulted in an increased frequency of adverse effects. Although nadolol and diltiazem have low incidences of side effects as monotherapy, little is known about their combination. Thus, 18 patients with angina pectoris despite medical therapy were randomly assigned to 3-week periods of nadolol (160 mg/day), diltiazem (240 mg/day) or their combination. At the end of each treatment period, treadmill exercise testing and rest and peak bicycle exercise 2-dimensional echocardiography were performed. The heart rate-systolic blood pressure product was decreased most at peak treadmill exercise with the combination therapy versus monotherapy with either nadolol or diltiazem (12 vs 14 vs 22 x 10(3), respectively, p less than 0.05). Exercise duration did not differ with any of the 3 regimens, but the number of patients without angina during exercise was lowest with the combination therapy versus nadolol or diltiazem alone (5, 10 and 11, respectively, p less than 0.05); similar results were noted with the number of patients developing 1-mm ST depression on the exercise electrocardiogram (6, 10 and 13, respectively, p less than 0.05). The left ventricular ejection fraction at rest and during peak exercise was similar among the 3 treatments. The therapeutic combination of nadolol and diltiazem is well tolerated and results in less evidence of myocardial ischemia during exercise than monotherapy with either agent.

Coronary vasomotor and clinical effects of nifedipine in effort, mixed and Prinzmental angina

Changes induced by nifedipine (10 mg s.l.) in the residual lumen diameter of significant (greater than 50%) coronary lesions were assessed angiographically in 69 patients with effort angina (Group 1), in 22 patients with mixed angina (Group 2), and in 14 patients with Prinzmental angina (Group 3). These changes were related to the clinical response to treatment with the same drug (diary records, exercise testing, Holter monitoring). In Groups 1 and 2 segments of stenotic vessels showed either increase, decrease or no change in diameter with the calcium antagonist; in Group 3 the majority of the vessels showed compliant portions which invariably responded with dilatation. Nifedipine failed to improve cases with exertional (21% unchanged, 19% worsened) and mixed (41% exacerbated) forms; all patients with the Prinzmental form had relief of the anginal episodes. In Group 1, the response to exercise tests were dissociated from the acute vasomotor pattern and the pressure-rate product failed to explain the clinical results. Fifty-two percent of the patients in Group 2 showed significant acute widening of critical stenoses as well as obvious improvement; patients in this group who did worse with treatment had reacted to nifedipine with narrowing of their critical stenoses. These data suggest that: the response to nifedipine of classic effort angina is probably the net result of an interaction of changes in myocardial oxygen consumption and supply; coronary vasomotion has a role in mixed angina and influences of nifedipine may be either favorable or unfavorable; stenotic lesions in the Prinzmental form are quite sensitive to the relaxant action of calcium blockade and this probably represents a background to the highly positive clinical response to treatment.

Antianginal efficacy of gallopamil in comparison to nifedipine

In a randomized double-blind crossover trial 30 patients with chronic stable angina were studied to compare the antianginal actions of gallopamil (150 mg/day) and nifedipine. With the initial nifedipine dose of 60 mg/day, the trial had to be stopped because of severe exacerbation of angina in 3 patients of the nifedipine group. Twenty-one patients were entered into a second protocol with the nifedipine dose reduced to 30 mg/day. Compared to the preceding placebo period, the exercise time to onset of angina (+ 30%, P less than 0.01) and the total exercise time (+ 18%, P less than 0.01) were prolonged by gallopamil but not by nifedipine (+ 20 and 13%, respectively, not significant) with no significant difference between the test drugs. Four patients became free of angina during exercise testing with gallopamil therapy and one patient with nifedipine. Both agents significantly reduced ST depression at maximal comparable workload by 77% (gallopamil) and 52% (nifedipine) compared with placebo; the difference between the drugs reached borderline significance (P = 0.055). The increase in heart rate and the rate-pressure product at maximal comparable workload was less with gallopamil than with nifedipine (P less than 0.01). In contrast to nifedipine, very few side effects were reported with gallopamil. Thus, gallopamil is an effective antianginal agent whose therapeutic to toxic ratio appears to be superior to that of nifedipine.

Nifedipine and angina pectoris. Short-term changes in quantitative coronary angiography with nifedipine and clinical response to treatment in effort-induced, mixed, and spontaneous angina pectoris

Changes induced by nifedipine (10 mg sublingually) in the residual luminal diameter of significant (greater than 50 percent) coronary lesions were assessed angiographically in 69 patients with effort-induced angina (group 1), in 22 patients with mixed angina (group 2), and in 14 patients with Prinzmetal's angina (group 3). These changes were related to the clinical response to treatment with the same drug, as evaluated through diary records and Holter monitoring in the mixed (spontaneous component) and Prinzmetal forms and through exercise testing in effort-induced and mixed (effort-associated component) angina. In groups 1 and 2, segments of stenotic vessels showed either an increase or decrease or no change in diameter with the calcium antagonist; in group 3, the majority of the lesions had compliant portions which invariably responded with dilatation. Nifedipine failed to improve cases with exertional (20 percent [14/69] unchanged; 19 percent [13/69] worsened) and mixed (41 percent [9/22] exacerbated) forms; 100 percent of the 14 patients with the Prinzmetal form had relief of the anginal episodes. In group 1, the response to exercise tests was dissociated from the short-term vasomotor pattern, and the pressure-rate product failed to explain the clinical results. Forty-five percent (ten) of the patients in group 2 showed significant short-term widening of critical stenoses, as well as obvious improvement; patients who did worse with treatment in this group had reacted to nifedipine with narrowing of critical stenoses. These data suggest that the response to nifedipine of classic effort-induced angina is probably the net result of an interaction of changes in myocardial oxygen consumption and supply; coronary vasomotion has a role in mixed angina, and influences of nifedipine may be either favorable or unfavorable; stenotic lesions in the Prinzmetal form are quite sensitive to the relaxant action of calcium blockade, and this probably represents a background to the highly positive clinical response to treatment.

Calcium channel antagonists. Part II: Use and comparative properties of the three prototypical calcium antagonists in ischemic heart disease, including recommendations based on an analysis of 41 trials

An analysis of 41 trials of angina of all varieties confirms that calcium antagonists are an important advance and are now established therapy for these syndromes. In effort angina, verapamil in a dose of 360-480 mg daily is better than propranolol in standard doses. Although nifedipine is highly effective against vasospastic angina, its use in threatened myocardial infarction or severe unstable angina is not supported by recent studies, unless combined with a beta-blocker. Diltiazem has recently been tested with apparent benefit in non-Q-wave myocardial infarction. Otherwise, these calcium antagonist agents all seem to have approximate equipotency in clinical ischemic syndromes including effort and vasospastic angina. Subjective side effects seem most troublesome in the case of nifedipine. All three calcium antagonists, especially nifedipine, have been successfully combined with beta-blocker therapy, yet occasional additive negative inotropic or chronotropic or dromotropic interactions may occur when verapamil or diltiazem is added to beta-blockade, and occasionally the direct negative inotropic potential of nifedipine may become evident. The choice between the calcium antagonists is determined not only by the clinical picture but also by the anticipated side effects in a given patient and by the overall cardiovascular status. In patients with supraventricular tachycardias or sinus tachycardia, verapamil or diltiazem is preferred, whereas in patients with a resting bradycardia or borderline heart failure nifedipine is likely to be chosen.

The antianginal efficacy and tolerability of controlled-release metoprolol once daily: a comparison with conventional metoprolol tablets twice daily

In a randomized, double-blind, cross-over study treatment with a new controlled-release (CR) preparation of metoprolol, given once daily, was compared with treatment with conventional metoprolol tablets, given twice daily, in 115 patients with stable effort angina pectoris. The patients were treated with 100 mg/day or 200 mg/day, depending on their previous beta-blocker dose. Antianginal efficacy was estimated by counting the number of anginal attacks, by noting the consumption of nitroglycerin tablets, and by exercise tolerance testing. Adverse effects were recorded by a standardized questionnaire. When all patients were analysed together there were no differences in antianginal efficacy between the two treatment regimens. However, when the group taking 200 mg daily was analysed separately better exercise tolerance was found during metoprolol CR therapy, as measured by onset of chest pain and ST-segment change, compared with conventional metoprolol therapy. The two formulations were well tolerated. When given once daily in a total daily dose of 100 mg, the CR preparation induced less adverse effects than the conventional tablets, 50 mg twice daily. It was concluded that the new metoprolol CR preparation, given once daily, possesses the same antianginal efficacy as conventional metoprolol tablets, given twice daily, and may be better tolerated in patients susceptible to side-effects. The antianginal effect of metoprolol CR, 200 mg/day, may be greater over 24 h than that produced by conventional metoprolol tablets, 100 mg twice daily.

Hemodynamic effects of metoprolol and nifedipine in angina pectoris measured by isotope technique

In order to evaluate the therapeutic effects of metoprolol, nifedipine, and their combination, 11 patients with secondary angina pectoris and with thallium tomographic findings indicating coronary artery disease were studied before and after these three treatment regimes in a single-blind cross-over study. The therapeutic effect was measured by standardized working test and isotope angiocardiography, which enabled evaluation of left ventricular ejection fraction, stroke volume, and phase analysis of left ventricular contraction. Treatment with metoprolol and combination therapy increased work performance. Ejection fraction did not differentiate the treatment regimes, whereas stroke volume was significantly lower at work and heart rate higher at rest and at work during nifedipine treatment compared to either metoprolol or combination treatment (p less than 0.05). Cardiac output was significantly reduced during nifedipine and metoprolol treatment during work (p less than 0.05). Phase improved after all therapeutic regimes, but reached significance only during the metoprolol treatment period at rest (p less than 0.05).

Differential effects of 1,4-dihydropyridine calcium channel blockers: therapeutic implications

Increasing recognition of the importance of calcium in the pathogenesis of cardiovascular disease has stimulated research into the use of calcium channel blocking agents for treatment of a variety of cardiovascular diseases. The favorable efficacy and tolerability profiles of these agents make them attractive therapeutic modalities. Clinical applications of calcium channel blockers parallel their tissue selectivity. In contrast to verapamil and diltiazem, which are roughly equipotent in their actions on the heart and vascular smooth muscle, the dihydropyridine calcium channel blockers are a group of potent peripheral vasodilator agents that exert minimal electrophysiologic effects on cardiac nodal or conduction tissue. As the first dihydropyridine available for use in the United States, nifedipine controls angina and hypertension with minimal depression of cardiac function. Additional members of this group of calcium channel blockers have been studied for a variety of indications for which they may offer advantages over current therapy. Once or twice daily dosage possible with nitrendipine and nisoldipine offers a convenient administration schedule, which encourages patient compliance in long-term therapy of hypertension. The coronary vasodilating properties of nisoldipine have led to the investigation of this agent for use in angina. Selectivity for the cerebrovascular bed makes nimodipine potentially useful in the treatment of subarachnoid hemorrhage, migraine headache, dementia, and stroke. In general, the dihydropyridine calcium channel blockers are usually well tolerated, with headache, facial flushing, palpitations, edema, nausea, anorexia, and dizziness being the more common adverse effects.

Long term efficacy of a controlled-release formulation of isosorbide 5-mononitrate (Imdur) in angina patients receiving beta-blockers

In a multicentre double-blind crossover study the clinical efficacy and tolerability of a controlled-release formulation, Durules, of isosorbide 5-mononitrate (Imdur) 60mg once daily was compared with placebo over 2 weeks in 70 patients with stable exercise-induced angina pectoris who were receiving concomitant long term beta-blockade. Isosorbide 5-mononitrate significantly improved exercise capacity and signs of myocardial ischaemia, while reducing the number of anginal attacks and consumption of short-acting glyceryl trinitrate tablets compared with beta-blocker therapy alone. During an open follow-up period of 1 year, there was no attenuation of the antianginal efficacy of isosorbide 5-mononitrate. The drug was well tolerated during both phases of the study, and the only significant adverse effect was headache, which rapidly disappeared during continued treatment.

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

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