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

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.

The calcium antagonist controversy: the emerging importance of drug formulation as a determinant of risk

Calcium antagonists are one of the widely available classes of antihypertensive agents. Their broad appeal is attributable to several features, including their efficacy, their beneficial characteristics such as metabolic neutrality, and the occurrence of relatively few nuisance-type side effects. Despite these attributes, a number of retrospective analyses have suggested that calcium antagonists may be detrimental and may both promote adverse cardiovascular events and increase the risk of cancer by interfering with cellular apoptosis. On the basis of this and other retrospective analyses, Furberg and Psaty (Am J Hypertens 1996; 9: 122-125) have proposed that the use of calcium antagonists as first-line antihypertensive agents should be discontinued. I have previously countered these allegations and have suggested that they are not relevant to the newer calcium antagonist formulations in current use. It is not widely appreciated that different formulations of the same chemical moiety can produce markedly different hemodynamic and neurohormonal effects, due to differences in the rate of drug delivery into the systemic circulation. During chronic treatment with dihydropyridine calcium antagonists, major fluctuations in blood pressure (rapid onset and offset of antihypertensive effects) during the dosing interval may occur for drugs and formulations that are short acting. In contrast, slow-release formulations of otherwise rapidly absorbed dihydropyridines achieve a more gradual and sustained antihypertensive effect. It is probable that newer calcium antagonist formulations that are truly once daily and do not provoke intermittent sympathetic activation or a cardioacceleratory response will not promote adverse cardiovascular events.

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)

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)

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.

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.

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.

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.

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).

The total vascular burden, peripheral and coronary: vasodilator effects of nifedipine

While the total ischemic burden on the left ventricle represents the combined effects of both symptomatic and asymptomatic myocardial ischemia, the total vascular burden has many components including an increased systemic peripheral vascular resistance, an increased pulmonary vascular resistance, and an increased coronary vascular resistance. These factors may all influence ventricular function. Hypertension contributes significantly to the vascular burden, especially when combined with left ventricular hypertrophy, which predisposes to ischemia by multiple mechanisms. In patients with hypertension and cardiomegaly, sublingual nifedipine has been shown to increase left ventricular (LV) ejection fraction and the average diastolic filling rate. In the presence of acute myocardial infarction, nifedipine moves the LV function curve onto a better Frank-Starling relationship as pulmonary wedge pressure falls or stays the same and cardiac output rises. However, because of the delicate balance between myocardial perfusion and the benefits of afterload reduction, including improved remodelling, nifedipine should be given only to selected patients. In congestive heart failure, low-dose nifedipine reduces the afterload and has been shown to have beneficial effects in the majority of patients. Two specific adverse outcomes in only two patients have been reported, one with initial hypotension and one given high-dose nifedipine. Combination nifedipine-beta blocker therapy has been shown to be favorable in the treatment of all varieties of angina, hypertension, and hypertrophic cardiomyopathy. Therefore, when administered appropriately, nifedipine reduces the total vascular burden on the heart in a variety of cardiovascular diseases, with consequent improvement in LV function and a diminished threat of potential myocardial ischemia.

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.

Effect of nifedipine on left ventricular function in patients with angina pectoris

Calcium channel blocking agents function as negative inotropic agents when they are administered in vitro directly to the myocardium. In patients with coronary artery disease, however, such direct effects are attenuated by a number of other factors, including decreased afterload and resultant reflex sympathetic stimulation, increased coronary blood flow with improved myocardial perfusion, and protection of mitochondria. Nifedipine has not been observed to cause significant left ventricular depression in patients with angina pectoris; this is primarily due to peripheral arteriolar vasodilatation, which reduces impedance of left ventricular ejection. In addition, the relief of myocardial ischemia by nifedipine plays a major role in improving systolic and diastolic function. The clinical response to calcium channel blockers may differ in patients with idiopathic dilated cardiomyopathy, for whom the factor of fluctuating ischemia is less important.