The Nifedipine-Total Ischemia Awareness Program: a national survey of painful and painless myocardial ischemia including results of antiischemic therapy

Pharmacotherapy of Vasospastic Angina

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

Analysis of arrhythmias in the Circadian Antiischemia Program in Europe (CAPE) study

The aim of this study was to analyze whether, in patients with long-standing (>4 years) coronary artery disease (CAD), the addition of the long-acting calcium channel blocker (CCB) amlodipine to conventional treatment [beta-blockers (BBLs) and nitrates] during anginal attacks would have a proarrhythmic effect. This was tested by analyzing data from patients who had taken part in the Circadian Anti-ischemia Program in Europe (CAPE) trial. After a 2-week, single-blind, run-in period (Phase 1), patients were randomized to amlodipine, 5 mg/day (first 4 weeks) and 10 mg/day (second 4 weeks), or placebo for 8 weeks (Phase 2). The 48-h Holter data were analyzed for 167 amlodipine-treated patients and 83 placebo patients based on a 2:1 randomization scheme. Sixty-three per cent of amlodipine patients and 67% of placebo patients were receiving concomitant BBLs, and >90% had taken sublingual nitrates during anginal attacks, as basic antiischemic therapy. After 7 weeks of therapy, when 48-h Holter monitoring was repeated, there were no significant changes in the frequency of ventricular arrhythmias in the placebo or amlodipine groups for all patients or subgroups of patients with or without BBLs. Also, between-group comparisons showed no significant differences in arrhythmias between amlodipine and placebo patients. In summary, amlodipine (5-10 mg/day) given to patients with severe, chronic CAD receiving conventional antiischemic therapy, did not produce any proarrhythmic effects.

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

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

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

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

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

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

Amlodipine in chronic stable angina: results of a multicenter double-blind crossover trial

The efficacy and safety of amlodipine, 10 mg, a new long-acting calcium antagonist, was compared with placebo in 103 patients with stable angina pectoris in a multicenter double-blind crossover study. The trial consisted of an initial 2-week single-blind placebo period followed by a first period of 4 weeks of double-blind therapy, which was followed by a 1 week washout period and then a second 4-week double-blind period after treatments were crossed over. Twenty-four-hour Holter electrocardiographic monitoring was carried out in 12 patients at three centers. In the first double-blind period amlodipine produced a significantly greater increase in symptom-limited exercise duration (amlodipine 478.5 to 520.6 vs placebo 484.6 to 485.2 seconds; change +8.8% vs +0.1%, respectively; p = 0.0004) and total work (amldipine 2426 to 2984 vs placebo 2505 to 2548 kilopondmeters; change +24% vs +1.7%, respectively; p = 0.0006) and a decrease in angina attack frequency (from 3 to 1 per week; p = 0.016) and nitroglycerin consumption (from 2 to 0.5 tablets/wk; p = 0.01) compared with placebo. Holter monitoring revealed significant reductions in numbers (amlodipine 4.65 to 2.22 vs placebo 1.84 to 1.54; change -52% vs +84%, respectively; p = 0.06), absolute total area (amlodipine 87.66 to 11.43 vs placebo 5.76 to 35.24; change -87% vs +513%, respectively; p = 0.02), and duration (amlodipine 12.29 to 2.95 vs 1.66 to 7.74 seconds; change -76% vs +367%, respectively; p = 0.008) of ST-segment depressions after treatment with amlodipine compared with placebo. After the treatments were crossed over changes continued to favor amlodipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Amlodipine reduces transient myocardial ischemia in patients with coronary artery disease: double-blind Circadian Anti-Ischemia Program in Europe (CAPE Trial)

OBJECTIVES

This study was carried out to determine the effect of the once-daily calcium channel blocking agent amlodipine (half-life 35 to 50 h) on the circadian pattern of myocardial ischemia in patients with chronic stable angina.

BACKGROUND

Myocardial ischemia during normal daily life, both symptomatic and asymptomatic, has been associated with increased risk of cardiovascular morbidity and mortality, and the circadian pattern parallels that for myocardial infarction and sudden death.

METHODS

The Circadian Anti-Ischemia Program in Europe (CAPE) was a large, 10-week international (63 sites), double-blind, parallel study. After a 2-week, single-blind placebo phase, during which stable doses of antianginal treatment were maintained (beta-adrenergic blocking agents in 65% of patients), patients with chronic stable angina with at least three attacks of angina per week, with at least four ischemic episodes or > or = 20 min of ST segment depression in 48 h of Holter monitoring, were randomized to receive treatment with either 5 mg/day of amlodipine or placebo (2:1 randomization). The dose was increased to 10 mg/day after 4 weeks. During week 7 of treatment, 48-h ambulatory ECG monitoring was repeated.

RESULTS

Three hundred fifteen of 1,160 patients screened were eligible, and 250 had complete evaluable data. Compared with placebo, amlodipine significantly reduced both the frequency of ST segment depression episodes (60% for amlodipine vs. 44% for placebo, p = 0.025) and total integrated ST ischemic area (62% mm-min vs. 50% mm-min, p = 0.042). Amlodipine reduced ischemia over the 24 h with the intrinsic circadian pattern maintained. In addition, diary data showed a significant reduction in angina (70% for amlodipine vs. 44% for placebo, p = 0.0001) and in nitroglycerin consumption (67% vs. 22%, respectively, p = 0.0006). Amlodipine and placebo demonstrated similar safety profiles (adverse events 17.3% for amlodipine and 13.3% for placebo; discontinuation rates due to adverse events were 2% vs. 4.4%, respectively).

CONCLUSIONS

Once-daily amlodipine, when added to background treatment, significantly reduced both symptomatic and asymptomatic ischemic events over 24 h in patients with chronic stable angina.

Silent myocardial ischemia: to treat or not to treat?

The risk of infarction and sudden death is considerable in patients with silent ischemia, whether it occurs alone or is interspersed with episodes of angina. The ischemic activity can be modified or even abolished, most effectively with beta-blocker and nitrate therapy. But it is not yet clear whether treatment improves outcome, although the limited available data suggest that it does.

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment

BACKGROUND

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD).

METHODS AND RESULTS

The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both).

CONCLUSIONS

Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

Prevalence and functional significance of transient ST-segment depression during daily life activity: comparisons of ambulatory ECG with stress redistribution thallium 201 single-photon emission computed tomographic imaging

To assess the prevalence and functional significance of ischemic ambulatory ECG responses, we prospectively performed ambulatory ECG monitoring in 244 patients (mean age 61 +/- 10 years) referred for stress redistribution thallium 201 myocardial perfusion scintigraphy. The prevalence of ST-segment depression during ambulatory ECG was 33% among patients with a positive exercise ECG, but prevalence varied in selected patient subgroups. Among three groups with coronary artery disease (CAD), the group with ambulatory ECG ischemia (group 1) had a greater frequency of ischemic thallium responses (p = 0.07), a greater median number of reversible thallium defects (p < 0.05), and a greater summed thallium "reversibility" score (p < 0.05) than did the group with a positive exercise ECG but negative ambulatory ECG response (group 2) or that with negative exercise and ambulatory ECG responses (group 3). Exercise ST depression in group 1 versus group 2 was significantly greater (p = 0.002), occurred at a lower heart rate threshold (p = 0.002), and lasted longer after exercise (p = 0.001). Notably, one third of group 1 patients also manifested evidence of transient ischemic dilation of the left ventricle after exercise (p < 0.01 vs groups 2 and 3), a sign of severe ischemia. However, although functionally less "sick" than group 1 patients, 66% of group 2 patients and 50% of group 3 patients still had an ischemic thallium response, which was sometimes severe. Thus transient ischemia during ambulatory ECG monitoring identifies a functionally sicker cohort of patients with CAD and occurs in approximately one third of CAD patients with positive results of exercise tests. A negative ambulatory ECG response, however, does not exclude functionally significant disease among CAD patients. These results imply that caution should be applied in the interpretation of a negative ambulatory ECG response for the purpose of patient risk stratification.

Comparative efficacy of nifedipine gastrointestinal therapeutic system versus diltiazem when added to beta blockers in stable angina pectoris

To determine the relative efficacy of nifedipine gastrointestinal therapeutic system (GITS) and diltiazem, 20 patients with angina pectoris and coronary artery disease were studied in a double-blinded, placebo-controlled randomized crossover trial. All patients were taking concomitant beta blockers. Efficacy was assessed by symptoms, exercise treadmill testing, and ambulatory ST-segment monitoring at baseline and after 6 weeks on each medication. Mean daily dose was titrated to 119 +/- 7 mg (nifedipine GITS) and 342 +/- 59 mg (diltiazem). The addition of either nifedipine GITS or diltiazem resulted in a significant reduction in angina frequency, improvement in exercise treadmill duration (7 vs 7 and 8 minutes; baseline vs nifedipine GITS and diltiazem), time to angina onset (4 vs 7 and 7 minutes; baseline vs nifedipine GITS and diltiazem), and time to ST-segment depression (5 vs 6 and 7 minutes; baseline vs nifedipine GITS and diltiazem). There was no significant difference between nifedipine GITS and diltiazem with respect to the magnitude of improvement in anginal symptoms or exercise test parameters. Both nifedipine GITS and diltiazem reduced the overall frequency and duration of ischemic episodes on ambulatory monitoring, but this reduction was not statistically different. Thus, nifedipine GITS and diltiazem at maximally tolerated doses were equally effective at reducing angina and increasing exercise tolerance as beta blockers alone.

Attenuation of the circadian patterns of myocardial ischemia with nifedipine GITS in patients with chronic stable angina

The Nifedipine Gastro-Intestinal Therapeutic System (GITS) Circadian Anti-ischemia Program (N-CAP) was designed to test the effect of nifedipine GITS as monotherapy or in combination with a beta-adrenergic blocking agent on the circadian pattern of angina and silent ischemia in patients with chronic stable angina. At 118 sites in the United States, 1,174 patients were screened for entry into this study. To be eligible for participation patients were required to have at least two episodes of angina a week and at least two episodes of myocardial ischemia during 48-h ambulatory electrocardiographic (ECG) monitoring during the baseline placebo period. A total of 207 patients completed all phases of the study. Beta-blockers were continued in those patients already receiving them. In this 7- to 10-week single-blind placebo withdrawal study, a 1-week placebo run-in was followed by up to 5 weeks of single-blind titration with nifedipine GITS, a 4-week efficacy phase with an established dose and a final single-blind 2-week placebo withdrawal period. Ambulatory ECG monitoring was performed at the end of each placebo phase and at the end of the efficacy phase with a digital monitoring device that was validated in a pilot study. Overall, nifedipine GITS significantly reduced the weekly number of anginal episodes from 5.7 to 1.8 (p = 0.0001) and the number of ischemic events from 7.3 to 4 (p = 0.0001) reported during the 48-h monitoring periods, with a significant increase in both during the placebo withdrawal period. The baseline circadian pattern of ischemia showed an early morning peak and a secondary peak in the afternoon. Nifedipine GITS significantly reduced ischemia during the 48-h period when administered as monotherapy or in combination with a beta-blocker. Patients were also randomized to receive nifedipine GITS in either a morning or an evening dose. The two regimens resulted in equal anti-ischemic benefit. The primary side effect of nifedipine GITS was edema, which was dose related. In summary, nifedipine GITS reduced the number of anginal and ischemic episodes when given alone or in combination with a beta-blocker. Nifedipine GITS had a sustained effect: a single daily dose was effective over 24 h regardless of whether it was administered in the morning or evening. This study also suggests that combination therapy with nifedipine GITS and a beta-blocker is especially efficacious in reducing ischemia.

Effect on prognosis of abolition of exercise-induced painless myocardial ischemia by medical therapy

During exercise radionuclide ventriculography, many patients with coronary artery disease exhibit painless myocardial ischemia defined as an abnormal left ventricular ejection fraction response without accompanying angina. To see if complete suppression of such exercise-induced painless ischemia by anti-ischemic medication implies a better prognosis in medically treated coronary artery disease, 34 patients underwent repeat testing at 4 weeks receiving regular conventional therapy that rendered angina no worse than class I. With such therapy, painless ischemia was abolished in 12 patients (group I) and persisted in 22 (65%, group II). Both groups were similar in age, number of diseased vessels, proportion with previous myocardial infarction, exercise ejection fraction, and degree of exercise-induced painless ischemia at baseline. At 9 months, adverse events had occurred in 11 patients (2 patients with myocardial infarction, 4 with unstable angina, 2 with angioplasty and 3 with bypass surgery). Only 1 of 12 patients (8%) in group I had experienced events compared with 10 of 22 (45%) in group II (chi-square, 5.4; p less than 0.025; 95% confidence interval, 12 to 61%). Thus, the relative risk of adverse events in patients whose painless ischemia was abolished was only 18% of that in patients in whom it was persistent. These results suggest that (1) the abolition of exercise-induced painless ischemia by conventional symptom-dictated medical therapy confers a better short-term prognosis in medically treated coronary artery disease, and (2) therapeutic efficacy may need to be assessed by titration against ischemia and not against angina.

Silent myocardial ischemia after acute myocardial infarction

Silent ischemia after myocardial infarction has definite prognostic significance but should be interpreted within the context of other prognostic indicators. The rationale for therapeutic intervention is based on the prognostic implications of silent ischemia and the potentially deleterious effect of repeated episodes of ischemia on the integrity of the left ventricle. We measured parameters of ischemia in 20 patients who showed asymptomatic ischemic ST-T changes on exercise testing in the early phase after myocardial infarction. After diltiazem administration, a reduction of exercise-induced ST-T depression from 2.3 +/- 0.8 to 0.7 +/- 0.6 mm (p less than 0.01) occurred, and regional wall-motion score at exercise, determined by radionuclide angiography, improved significantly (p less than 0.02). These and other observations warrant further studies in which the duration, severity and frequency of the ischemic episodes should be quantified and correlated with prognosis after myocardial infarction.

Effect of diltiazem slow-release formulation on silent myocardial ischemia in stable coronary artery disease. The Canadian Multicenter Diltiazem Study Group

Silent myocardial ischemia is associated with adverse outcome in several subsets of coronary artery disease patients. This article presents results of a placebo-controlled, randomized, double-blind study of the effects of sustained-release diltiazem (180 mg twice daily) on ischemic episodes in 60 patients with documented coronary artery disease. The mean age of the study population was 60 years and 93% were male. The mean number of episodes of silent ischemia per patient was 5.6 (placebo) and 2.8 (diltiazem), a 50% reduction (p less than 0.0001). Duration of ST-segment depression was 119 minutes (placebo) and 67 minutes (diltiazem), a 44% reduction (p less than 0.001). This study demonstrates that sustained-release diltiazem can significantly reduce the frequency and total duration of silent ischemic episodes.

Effect of diltiazem on symptomatic and asymptomatic episodes of ST segment depression occurring during daily life and during exercise

BACKGROUND

Silent myocardial ischemia is an adverse prognostic marker in patients with coronary disease; however, controlled data on the effect of treatment are sparse and contradictory, and the relations among the occurrence of ST segment depression, drug efficacy, and heart rate are unclear.

METHODS AND RESULTS

Sixty patients with stable coronary artery disease, a positive treadmill exercise test and asymptomatic ST segment depression on ambulatory electrocardiographic recording were assessed in a multicenter, double-blind, placebo-controlled, cross-over trial. Treadmill exercise tests and 72-hour electrocardiographic recordings were obtained at the end of two 2-week treatment periods with sustained-release diltiazem 180 mg b.i.d. or equivalent placebo. Episodes of asymptomatic ST depression decreased by 50% or more in 70% of the patients from a median number of 4.5 (range, 0-19) to 1.5 (range, 0-13) (p = 0.0001); their cumulative duration also decreased from 78.5 (range, 0-60) to 24.5 (range, 0-411) minutes (p = 0.001). No circadian variation was found in the efficacy of diltiazem. The occurrence of ischemic type ST segment depression was modulated by changes in heart rate rather than by absolute heart rate. Diltiazem also improved exercise test end points but to a lesser extent. Time to ST segment depression increased to 341 +/- 148 from 296 +/- 154 seconds (p = 0.005). Although less frequent with diltiazem administration (45 versus 54 patients, p less than 0.03), exercise-induced ST depression was more often asymptomatic (98% versus 72% of patients, p less than 0.0001).

CONCLUSIONS

Diltiazem reduces the frequency and severity of ischemic type ST depression in patients with stable coronary artery disease.

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

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

Effects of atenolol alone, nifedipine alone and their combination on ambulant myocardial ischemia

The effects of atenolol (100 mg/day) and nifedipine (20 mg 3 times daily) and their combination on ambulant myocardial ischemia were investigated using a randomized, double-blind, placebo-controlled, crossover trial. Eighteen men with symptomatic coronary artery disease, exercise-induced ischemia and minimal symptoms, underwent 4 blinded treatment periods of 2 weeks' duration (2 placebo, 1 atenolol, 1 nifedipine). Those that did not have ischemia eliminated by monotherapy received combination therapy with both drugs. Forty-eight-hour ambulatory electrocardiographic monitoring was used to quantitate ischemic parameters at the end of each period. Both nifedipine and atenolol as monotherapy reduced the number of ischemic episodes and the average duration of each episode compared with placebo (p less than 0.05). Compared with placebo, nifedipine reduced the total duration of ischemia (p less than 0.05) but the effect of atenolol on ischemia duration was of borderline significance (p = 0.066). There were no differences in reduction of ischemic parameters when atenolol was compared with nifedipine (difference not significant). In the 9 patients who continued to have ischemia with monotherapy, combination therapy eliminated it in 2 and reduced the duration by greater than 50% in the remaining patients compared with placebo. In conclusion, monotherapy with nifedipine or atenolol is similarly effective in eliminating or reducing ambulant ischemia. Combination therapy can provide additional benefit in those with continued ischemia.

Effects of nisoldipine on myocardial ischemia during exercise and during daily activity

The antiischemic properties of nisoldipine, a dihydropyridine calcium antagonist, were assessed in a multicenter, double-blind, placebo-controlled trial by repeated exercise testing and 72-hour ambulatory electrocardiographic monitoring in 82 patients with coronary artery disease. Patients with positive treadmill stress test results and greater than or equal to 2 ischemic episodes per 24 hours were included in this study. Administration of all chronic antiischemic medications except beta blockers were discontinued. During the first week all patients received placebo twice daily. During the second and third weeks, 41 patients received nisoldipine 10 mg and 41 patients received placebo twice daily. In the placebo group there were no changes in exercise parameters or in ambulatory electrocardiographic parameters. In the nisoldipine group, exercise duration increased from 403 to 448 seconds (p = 0.0035), time to 1 mm of ST depression increased from 224 to 298 seconds (p = 0.002), time to pain increased from 241 to 321 seconds (p = 0.01), and maximal ST depression was reduced from 2.6 to 2.3 mm (p = 0.002). Among the ambulatory electrocardiographic parameters in the nisoldipine group, only the number of episodes was reduced, from 14.4 to 11.6 (p = 0.0013) per patient. There was no significant reduction in total ischemic time (132 vs 120 minutes per patient). No significant side effects were observed. This is the largest clinical trial to date on the effects of nisoldipine on myocardial ischemia. The results indicate that nisoldipine was effective in improving all exercise parameters and only partially effective in suppressing ischemia during daily activity.

Effect of nifedipine on total ischemic activity and circadian distribution of myocardial ischemic episodes in angina pectoris

A randomized, double-blind, crossover study was conducted in 10 patients to assess the effect of nifedipine versus placebo on total ischemic activity and circadian distribution of ischemic episodes. After baseline exercise treadmill testing and 48-hour ambulatory electrocardiographic ST-segment monitoring, patients received either nifedipine (mean dose, 80 mg/day) or placebo administered 4 times per day, with the initial dose taken immediately upon arising in the morning. Patients were maintained on a stable dose of each study drug for 7 days, after which they underwent repeat exercise treadmill testing and 48-hour ambulatory electrocardiography. During exercise treadmill testing, greater exercise duration was achieved by patients receiving nifedipine than by those receiving placebo (421 +/- 121 vs 353 +/- 155 seconds, respectively; p less than 0.05). Time to greater than or equal to 1 mm ST depression was significantly greater with nifedipine (282 +/- 146 seconds) than at baseline (130 +/- 72 seconds, p less than 0.003) and with placebo (150 +/- 98 seconds, p less than 0.0005). During ambulatory electrocardiographic monitoring, nifedipine reduced both the total number of ischemic episodes (18 vs 54 at baseline and 63 with placebo; p less than 0.02 for both) and the total duration of ischemia (260 vs 874 at baseline and 927 minutes with placebo; p less than 0.02 for both). The surge of ischemia between 06:00 and 12:00 noted at baseline and during placebo therapy was nearly abolished during nifedipine treatment. Nifedipine at this dosage, administered in this manner, is effective in reducing total ischemic activity and may prevent morning surges of ischemic episodes.

Rationale for treatment of silent myocardial ischemia: focus on nifedipine

The realization that the majority of ischemic episodes in ambulatory patients with coronary artery disease are not associated with angina has raised important questions regarding the medical management of such individuals. Data from studies utilizing ambulatory Holter monitoring of the ST segment suggest that ischemia is likely to be due to a combination of a modest rise in myocardial oxygen demand and a concomitant decrease in coronary perfusion. Patients with ambulatory ischemia may have a poorer survival than those without ischemia during daily activities. This paper will address the potential impact these new findings could have on treatment. A growing body of knowledge regarding the use of nifedipine for silent ischemia will be examined. Enthusiasm to make abolition of ischemia an end point of therapy in patients with coronary artery disease will necessitate a reexamination of drugs that have been assessed largely on their ability to provide symptomatic relief.

Aging and pain perception in ischemic heart disease

Age is a recognized risk factor for coronary artery disease, but the relationship between age and silent ischemia is not well understood. We analyzed the data from 35 rest/stress radionuclide ventriculography examinations in patients with documented ischemic coronary artery disease who had experienced 1 mm ST segment depression accompanied by angina during exercise testing. An index of ischemic cardiac pain perception (PPI) was calculated by subtracting the time of onset of 1 mm ST segment depression from the time of onset of angina. The mean value of PPI was -97 +/- 311 seconds. PPI was significantly correlated with age (r = 0.37, p = 0.03). This suggests that as age increases, perception of pain during myocardial ischemic episodes becomes muted. This relationship remained significant when we controlled for the presence of medication and severity of disease (change in ejection fraction from rest to peak exercise). These findings suggest that age is an independent risk factor for a decreased perception of ischemic cardiac pain, and thus for silent myocardial ischemia.

Prevalence and patterns of silent myocardial ischemia during daily life in stable angina patients receiving conventional antianginal drug therapy

The prevalence and patterns of silent myocardial ischemia were evaluated in 105 stable angina patients receiving conventional antianginal drug therapy. During 2,520 hours of electrocardiographic monitoring, silent ischemia was detected in 45 (43%) patients. A total of 188 ischemic episodes was observed; 163 (87%) were silent and accounted for a total ischemic duration of 5,771 minutes. There was no difference in the baseline clinical characteristics between the patients with and without ambulatory silent ischemia. However, patients with silent ischemia on ambulatory electrocardiographic monitoring had earlier onset of ischemia during exercise testing. The highest density of silent ischemic events occurred between 6 A.M. and 6 P.M. Comparison of the class or combination of antianginal agents used by the 2 groups revealed no difference. However, in patients with silent ischemia the mean duration per event was shorter for those receiving 2 (p less than 0.05) or more (p = 0.001) antianginal agents compared to those receiving monotherapy. The average duration of silent ischemia per event was significantly less (p less than 0.001) in patients receiving beta blockers. These results demonstrate that silent ischemia during ordinary daily activities occurs frequently despite conventional antianginal drugs prescribed for control of symptoms.