Angiotensin converting enzyme inhibition in chronic stable angina: effects on myocardial ischaemia and comparison with nifedipine

Effect of Pre-operative Angiotensinconverting Enzyme Inhibitors on Haemodynamic Parameters and Vasoconstrictor Requirements in Patients Undergoing Off-pump Coronary Artery Bypass Surgery

The effects of pre-operative angiotensin-converting enzyme inhibitor (ACEI) treatment on haemodynamic status and vasoconstrictor requirements during off-pump coronary artery bypass surgery (OPCAB) were studied. Eighty patients selected for OPCAB were divided into those who had been treated with ACEIs for 4 weeks or more pre-operatively (ACEI group) (n = 43) and those who had not been treated with ACEIs (control group) (n = 37). Noradrenaline was infused during the operation when the mean systemic arterial pressure (SAP) fell below 60 mmHg. No significant differences in the haemodynamic parameters measured were detected between the two groups, except for cardiac output, which was found to be significantly greater in the control group. During anastomosis of the obtuse marginal branch of the left circumflex artery (OM), a significantly larger amount of noradrenaline was required by the ACEI group compared with the control group. In conclusion, pre-operative treatment with ACEIs significantly increased the amount of vasoconstrictor necessary to maintain the target SAP during OM anastomosis during OPCAB.

Antianginal efficacy of omapatrilat in patients with chronic angina pectoris

Angiotensin-converting enzyme inhibition is not an effective antianginal therapy. Experimental data suggest that broader vasopeptidase inhibition may decrease the magnitude of demand-induced myocardial ischemia. A randomized, double-blind, placebo controlled parallel study evaluated omapatrilat, an inhibitor of angiotensin-converting enzyme and neutral endopeptidase. The primary objective was to compare maximum duration of exercise at peak plasma concentrations. Exercise treadmill studies were performed in 348 patients who had chronic angina at baseline and after 4 weeks of therapy with 80 mg/day omapatrilat or placebo. Safety data were collected and reported for all patients. Treadmill exercise duration at peak was significantly prolonged in the omapatrilat group compared with the placebo group (76.6 +/- 84.2 vs 28.7 +/- 82.2 seconds difference from baseline, p <0.001). Similar statistically significant increases were seen in time to onset of level III/IV angina and time to onset of >/=0.1-mV ST-segment depression (p <0.001). The significant improvements in exercise duration and measurements of myocardial ischemia were not sustained 20 to 28 hours after dosing. Omapatrilat was generally well tolerated in this predominantly normotensive population. The incidence of serious adverse events was 5.2% in the 2 groups. Thus, omapatrilat, an investigational vasopeptidase inhibitor, is effective in prolonging exercise duration and parameters of demand-induced myocardial ischemia in patients who have chronic angina at peak concentrations. The data confirm the proof of principle that broader vasopeptidase inhibition beyond angiotensin-converting enzyme inhibition is required to alleviate symptoms of chronic angina.

Effect of ramipril on postrevascularization prevalence of angina and quality of life

BACKGROUND

The prevalence of angina after invasive revascularization is not negligible and impacts on quality of life. It has not been clarified whether potential anti-ischemic actions of angiotensin-converting enzyme inhibitors (1) may apply to non high-risk patients and (2) may reduce the prevalence of angina. We sought to test the hypothesis that ramipril, an angiotensin-converting enzyme inhibitor, may reduce the postrevascularization prevalence of angina pectoris and improve quality of life.

METHODS

In the Angiotensin-converting enzyme Post-Revascularization Study (APRES), 159 patients who underwent invasive revascularization for chronic angina and who had not had heart failure, acute myocardial infarction (AMI), or severe left ventricular dysfunction were randomized to receive 10 mg of ramipril or placebo. During the 12- to 46-month follow-up, the Specific Activity Scale class, exercise tests, and SF-36 quality of life scores were serially assessed.

RESULTS

The average prevalence of angina of Specific Activity Scale class II or worse was 26.6% in the ramipril group and 19.9% in the placebo group (p=0.16). The average prevalence of exercise-inducible ischemia was 30.8% in the ramipril group and 25.2% in the placebo group (p=0.39). There were no significant differences between the two treatment groups in the SF-36 quality of life scores or in the Duke treadmill score. Post-hoc power calculations revealed that the power to rule out a clinical significant benefit of ramipril on the prevalence of angina, quality of life, and Duke treadmill score was >90%.

CONCLUSIONS

These data do not suggest that ramipril reduces the prevalence of angina pectoris or improves quality of life after invasive revascularization in such patients

Effects of angiotensin-converting enzyme inhibition on transient ischemia: the Quinapril Anti-Ischemia and Symptoms of Angina Reduction (QUASAR) trial

OBJECTIVES

We sought to determine whether angiotensin-converting enzyme inhibition (ACE-I) (i.e., quinapril) prevents transient ischemia (exertional and spontaneous) in patients with coronary artery disease (CAD).

BACKGROUND

It is known that ACE-I reduces the risk of death, myocardial infarction (MI), and other CAD-related outcomes in high-risk patients. Numerous studies have confirmed that ACE-I improves coronary flow and endothelial function. Whether ACE-I also decreases transient ischemia is unclear, because no studies have been adequately designed or sufficiently powered to evaluate this issue.

METHODS

Using a randomized, double-blinded, placebo-controlled, multicenter design, we enrolled 336 CAD patients with stable angina. None had uncontrolled hypertension, left ventricular (LV) dysfunction, or recent MI, and all developed electrocardiographic (ECG) evidence of ischemia during exercise. They were randomly assigned to one of two groups: 40 mg/day quinapril (n = 177) or placebo (n = 159) for 8 weeks. Patients then entered an additional eight-week treatment phase to examine the full dose range. Those assigned to 40 mg quinapril continued that dose and those assigned to placebo were titrated to 80 mg/day. Treadmill testing, the Seattle Angina Questionnaire, and ambulatory ECG monitoring were used to assess responses at baseline and at 8 and 16 weeks.

RESULTS

The groups did not differ significantly at entry or in terms of indexes assessing myocardial ischemia at 8 or 16 weeks of treatment. In this low-risk population, ACE-I was not associated with serious adverse events.

CONCLUSIONS

Our findings suggest short-term ACE-I in CAD patients without hypertension, LV dysfunction, or acute MI is not associated with significant effects on transient ischemia.

Vasopeptidase inhibition in a canine model of exercise-induced left ventricular dysfunction

1. The present study compared the acute efficacies of vasopeptidase inhibition with omapatrilat, nitroglycerin and angiotensin-converting enzyme (ACE) inhibition in exercise-induced myocardial dysfunction. Omapatrilat, a vasopeptidase inhibitor, inhibits both neutral endopeptidase and ACE. Whereas vasopeptidase inhibitors have demonstrated clinical efficacy in hypertension and heart failure, their effects in myocardial ischaemia remain unclear. 2. Omapatrilat (0.3 mg/kg) was compared with vehicle (saline), an ACE inhibitor (fosinoprilat; 0.44 mg/kg) and nitroglycerin (8.0 microg/kg per min), in an established canine model of exercise-induced myocardial dysfunction induced by progressive closure of an ameroid constrictor placed about the proximal circumflex coronary artery. Maximal treadmill exercise tests, terminated when heart rate failed to increase with increasing workload or failure to continue exercise, were performed in chronically instrumented dogs. 3. During exercise, omapatrilat and nitroglycerin similarly increased ischaemic wall thickening (P< or = 0.0001, ANOVA, 12 d.f.), whereas fosinoprilat and vehicle were without effect. Ischaemic zone ST changes were decreased with nitroglycerin (P = 0.0006, ANOVA, 12 d.f.) and tended to decrease with omapatrilat (P = 0.07, ANOVA, 12 d.f.). Peak exercise capacity was increased with nitroglycerin (9.7 +/- 1.1 vs 11.2 +/- 1.0 kcal, control vs 4 h, respectively; n = 6) and omapatrilat (9.7 +/- 0.8 vs 11.4 +/- 0.6 kcal, control vs 4 h, respectively; n = 6) and was unchanged with ACE inhibition (9.0 +/- 1.2 vs 9.5 +/- 1.1 kcal, control vs 4 h, respectively; n = 7). Omapatrilat differentially increased double product during exercise (P = 0.001, ANOVA, 12 d.f.) compared with other treatments. 4. During exercise-induced myocardial dysfunction, acute ACE inhibition did not attenuate ischaemic changes and failed to improve exercise capacity. Increased exercise capacity with omapatrilat was accompanied by a differential increase in double product, consistent with increased oxygen supply and demand. Improvements in ischaemic function were comparable between omapatrilat and nitroglycerin, suggesting that omapatrilat may represent a novel therapy in demand-induced ischaemia.

Trimetazidine for stable angina pectoris

Stable angina pectoris, a symptom of coronary heart disease (CHD), manifests as stress-induced ischaemic episodes resulting in severe chest pain. Therapeutic aims are to improve quality of life by decreasing anginal attacks and to prevent myocardial infarction (MI) and death. Current anginal medications include beta-blockers and calcium antagonists, which decrease ischaemic severity by reducing cardiac workload, and nitrates, which increase coronary blood flow. A new therapeutic approach is the use of metabolic agents, such as trimetazidine, which are cytoprotective during ischaemia. Results of several clinical trials demonstrated that trimetazidine, at the standard dose of 20 mg t.i.d., increased exercise capacity, decreased anginal incidence and decreased left-ventricular (LV) dysfunction compared to placebo. Trimetazidine was also as effective as propranolol (120 - 160 mg/day) and nifedipine (40 mg/day) in decreasing anginal episodes and improving exercise parameters. Trimetazidine improved anginal frequency and symptoms in patients in which treatment with diltiazem, nifedipine, propranolol, pindolol, oxprenolol or long-acting nitrates had failed. Trimetazidine was also more effective than isosorbide dinitrate (30 mg/day) as an adjunct to propranolol. Despite efficacy being equivalent to that of beta-blockers and calcium antagonists, trimetazidine does not depress cardiac function and, correspondingly, is not contraindicated in any condition. Adverse effects of trimetazidine are mild and infrequent. In summary, clinical data indicate that trimetazidine is a safe, effective treatment for the symptoms of stable angina pectoris when used either as a monotherapy or an adjunctive therapy. Longer-term trials are necessary to determine whether trimetazidine will be effective in reducing rates of mortality and MI.

No effects on myocardial ischaemia in patients with stable ischaemic heart disease after treatment with ramipril for 6 months

OBJECTIVE: To assess the effects of a 6-month angiotensin-converting enzyme (ACE) inhibitor intervention on myocardial ischaemia. METHOD: We randomized 389 patients with stable coronary artery disease to double-blind treatment with ramipril 5 mg/day (n = 133), ramipril 1.25 mg/day (n = 133), or placebo (n = 123). Forty-eight-hour ambulatory electrocardiography was performed at baseline, and after 1 and 6 months. RESULTS: Relevant baseline variables were similar in all groups. Changes over 6 months in duration of >/= 1 mm ST-segment depression (STD), total ischaemic burden and maximum STD did not differ significantly between the treatment groups. There was no difference in the frequency of adverse events between the groups. CONCLUSION: ACE inhibitor treatment has little impact on incidence and severity of myocardial ischaemia in patients with stable ischaemic heart disease.

Treatment of stable angina

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

Choosing the most appropriate treatment for stable angina. Safety considerations

The goals of stable angina pectoris treatment are: (i) symptom relief and increase in angina-free walking time; and (ii) reduction of mortality and adverse outcome. Strategies used for plaque stabilisation resulting in a reduction in cardiovascular mortality and morbidity are: smoking cessation; aspirin (acetylsalicylic acid); blood pressure control; lipid lowering agents when low density lipoprotein cholesterol is elevated despite dietary therapy; coronary bypass surgery in patients with left main stem disease or triple vessel coronary disease and diminished left ventricular function; and use of estrogen in postmenopausal women. For symptom relief and to increase angina-free walking time, long acting nitrates, beta-blockers, calcium antagonists and potassium channel openers can be used. Drugs from these 3 classes are all effective when used optimally and choice of initial therapy should consider the presence of concomitant disease and underlying left ventricular function. However, none of the long acting nitrates provide continuous prophylaxis because nitrate tolerance develops during long term therapy. In patients with uncomplicated stable angina, nitrates, beta-blockers and calcium antagonists are all effective. Intermittent nitrate therapy is not associated with tolerance, but headache is a common adverse effect and the patient is unprotected at night and in the early hours of the morning. Concomitant treatment with a beta-blocker may be beneficial if the patient experiences withdrawal or early morning angina. For patients with stable angina and hypertension, therapy with a beta-blocker or a calcium antagonist rather than nitrate is indicated. beta-Blockers are preferred in patients who have had a myocardial infarction, or in those with a history of supraventricular tachyarrhythmias. beta-Blockers may produce excessive slowing of the heart rate, fatigue and bronchospasm in susceptible patients. Calcium antagonists are indicated as initial therapy when beta-blockers are either not tolerated or contraindicated. beta-Blockers and nondihydropyridine calcium antagonists should not be used in patients with sinus bradycardia and those with greater than first degree atrioventricular (AV) block because of the possibility of further slowing of heart rate and/or the development of high grade AV block. When monotherapy with one class is ineffective or associated with adverse effects, the patient should be switched to another class rather than given an additional drug. Optimal monotherapy is often as effective as combination therapy. If maximum monotherapy is only partially effective, a combination therapy which is not additive in terms of adverse effects should be chosen. Triple therapy may be deleterious and no more effective than dual therapy.

The Effects of Sublingual Administration of Captopril on Parameters of Exercise Test and Neurohormonal Activation in Patients With Stable Angina Pectoris

A prospective randomized, double-blind, and placebo-controlled study was designed to investigate the effects of sublingual administration of captopril on the parameters of exercise test and neurohormonal activation in patients with stable angina pectoris. A total of 31 patients (28 male, 3 female; mean age 55.4 +/- 9.4 years) took part in the study. Coronary angiography and left ventriculography were performed in all cases and the patients were classified according to the ejection fraction (EF). Following sublingual placebo or 25 mg captopril, plasma levels of renin, angiotensin II, norepinephrine, and serum aldosterone levels were measured at rest and maximal exercise. test was performed. Hormone levels were remeasured immediately after the exercise. The same procedure was repeated the next day using captopril or placebo. Sublingual captopril administration increased the time to angina, the time to 1 mm ST depression, maximal exercise capacity, maximal exercise duration and decreased maximal ST depression, maximal systolic blood pressure, and maximal double product (p < 0.001-0.01). After the maximal exercise test following captopril, the % difference of angiotensin II, aldosterone, and norepinephrine levels was found to be significant lower and the % difference of the renin level was found to be significantly higher than those of placebo (p < 0.001). The effects of sublingual captopril on exercise parameters were additionally assessed in different left ventricular systolic function subgroups. The favorable effects were more prominent in cases with left ventricular systolic dysfunction. There were no adverse effects related to sublingual captopril use. As a result, sublingual administration of captopril improved the parameters of maximal exercise test and suppressed the neurohormonal activation during exercise. We suggest that sublingual captopril may be used effectively before planned daily activities in patients with stable angina pectoris.