Antianginal drug therapy for silent myocardial ischemia

Differences between male and female patients with regard to baseline demographics and clinical outcomes in the Asymptomatic Cardiac Ischemia Pilot (ACIP) Trial

BACKGROUND

Coronary artery disease (CAD) is a common problem in men and women; however, men and women with similar clinical presentations of myocardial ischemia may receive different revascularization treatments.

HYPOTHESIS

Using the data base of the Asymptomatic Cardiac Ischemia Pilot (ACIP) trial, this study was undertaken to compare by gender the baseline demographic data and the clinical outcome results in patients randomized to various treatments in the ACIP study.

METHODS

This randomized trial compared three treatment regimens [pharmacologic management of angina, pharmacologic management of angina and ambulatory electrocardiographic (ECG) evidence of ischemia, and revascularization--that is, angioplasty and coronary artery bypass surgery], in patients with known CAD, positive stress ECG tests, and ECG evidence of ischemia during 48 h ambulatory monitoring. In all, 558 patients were randomized, 79 of whom were women (mean age: men 61.6 years, women 60.6 years) Ambulatory ECG evidence of ischemia, clinical events, that is, death, myocardial infarction, hospital admission for coronary events, and exercise performance were monitored.

RESULTS

Although of the same age as men at baseline, women had a higher prevalence of hypertension and diabetes. Women had less severe CAD by angiography and higher left ventricular ejection fractions. Men had longer exercise tolerance times on the treadmill. However, men and women had similar numbers and duration of ambulatory ECG ischemic abnormalities. Regarding revascularization, men more commonly underwent coronary artery bypass surgery (p = 0.025) while women underwent percutaneous transluminal coronary angioplasty more frequently (p = 0.10). Clinical outcomes were comparable in men and women, although the numbers of events were relatively small.

CONCLUSIONS

Men and women of comparable age manifest CAD with similar ischemic ECG abnormalities seen on both exercise tolerance and ambulatory ECG examinations. In ACIP, women tended to have more risk factors for CAD and less severity in anatomical disease, which may explain why women are less likely than men to have coronary bypass surgery.

Asymptomatic Cardiac Ischemia Pilot (ACIP) study: outcome at 1 year for patients with asymptomatic cardiac ischemia randomized to medical therapy or revascularization. The ACIP Investigators

OBJECTIVES

This report discusses the outcome at 1 year in patients in the Asymptomatic Cardiac Ischemia Pilot (ACIP) study.

BACKGROUND

Comparative efficacy of medical therapy versus revascularization in treatment of asymptomatic ischemia is unknown. The ACIP study assessed the ability of three treatment strategies to suppress ambulatory electrocardiographic (ECG) ischemia to determine whether a large-scale trial studying the impact of these strategies on clinical outcomes was feasible.

METHODS

Five hundred fifty-eight patients with coronary anatomy amenable to revascularization, at least one episode of asymptomatic ischemia on the 48-h ambulatory ECG and ischemia on treadmill exercise testing were randomized to one of three treatment strategies: 1) medication to suppress angina (angina-guided strategy, n = 183); 2) medication to suppress both angina and ambulatory ECG ischemia (ischemia-guided strategy, n = 183); or 3) revascularization strategy (angioplasty or bypass surgery, n = 192). Medication was titrated atenolol-nifedipine or diltiazem-isosorbide dinitrate.

RESULTS

The revascularization group received less medication and had less ischemia on serial ambulatory ECG recordings and exercise testing than those assigned to the medical strategies. The ischemia-guided group received more medication but had suppression of ischemia similar to the angina-guided group. At 1 year, the mortality rate was 4.4% in the angina-guided group (8 of 183), 1.6% in the ischemia-guided group (3 of 183) and 0% in the revascularization group (overall, p = 0.004; angina-guided vs. revascularization, p = 0.003; other pairwise comparisons, p = NS). Frequency of myocardial infarction, unstable angina, stroke and congestive heart failure was not significantly different among the three strategies. The revascularization group had significantly fewer hospital admissions and nonprotocol revascularizations at 1 year. The incidence of death, myocardial infarction, nonprotocol revascularization or hospital admissions at 1 year was 32% with the angina-guided medical strategy, 31% with the ischemia-guided medical strategy and 18% with the revascularization strategy (p = 0.003).

CONCLUSIONS

After 1 year, revascularization was superior to both angina-guided and ischemia-guided medical strategies in suppressing asymptomatic ischemia and was associated with better outcome. These findings require confirmation by a larger scale trial.

Time significance of acute thrombotic reactant markers in patients with and without silent myocardial ischemia and overt unstable angina pectoris

Ischemic electrocardiographic changes were recorded within 2 hours of admission using a 12-lead electrocardiographic continuous monitor with a 20-second scanning interval and an alarm mode for asymptomatic events. Blood samples were obtained at admission and at the moment of asymptomatic events (group A). In the other patients who did not develop ischemia, a second blood sample was taken 12 hours later (group B). We determined prothrombin time, activated partial thromboplastin time, clotting factor VIII activity, tissue plasminogen activator activity, tissue plasminogen activator inhibitor-1, cross-linked fibrin degradation product, and thrombin-antithrombin III complexes. There was a statistically significant difference between group A and B patients when the basal samples were analyzed for thrombin-antithrombin III (p = 0.046) and d-Dimer (p = 0.005). Prothrombin fragment 1 + 2 were significantly reduced, and d-Dimer was elevated when basal blood samples were compared with the second sample in patients who developed silent events (p = 0.008 and 0.055, respectively). A plasma concentration of thrombin-antithrombin III complex was also significantly decreased when sample 2 was compared with the basal blood sample (p = 0.039). Five recurrent episodes of angina and 2 nonfatal infarctions occurred, and 4 urgent revascularization procedures were performed in group A. In group B, there was only 1 nonfatal infarction (p = 0.01). The results of the present study suggest that a time-dependent thrombotic process is detectable in the blood stream as a cyclic movement. Further studies are needed to determine if some other factors, such as intensive shear stress in the vessel wall, may activate plaque instability during asymptomatic 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.

Comparison of propranolol, diltiazem, and nifedipine in the treatment of ambulatory ischemia in patients with stable angina. Differential effects on ambulatory ischemia, exercise performance, and anginal symptoms. The ASIS Study Group

Episodes of transient myocardial ischemia during ambulatory activities are common in patients with stable coronary artery disease and who are often asymptomatic. Selection of therapy for episodes of asymptomatic ischemia is limited by a lack of direct comparative studies. To determine the most effective monotherapy for patients with stable angina and a high frequency of asymptomatic ischemic episodes, propranolol-LA (mean daily dose, 293 mg), diltiazem-SR (mean daily dose, 350 mg), nifedipine (mean daily dose, 79 mg) were each compared with placebo, each for 2 weeks, in a randomized, double-blinded, crossover trial. Entry criteria were a positive exercise treadmill test during placebo therapy characterized by 1.0 mm or more ST segment depression and angina pectoris, and six or more episodes of transient ST segment depression of 1.0 mm or more on a 48-hour ambulatory electrocardiogram. One hundred ninety-four patients were screened, 63 were eligible and received randomized therapy, of which 56 patients completed at least two of the four treatment periods and were included in an intent-to-treat analysis. Fifty patients completed all four treatment phases and were included in the protocol-completed analysis. Anti-ischemia efficacy was assessed by 48-hour ambulatory electrocardiographic monitoring, exercise treadmill tests, and anginal diaries. Ninety-four percent of all episodes of ambulatory ischemia were asymptomatic. Compared with placebo, only propranolol was associated with a marked reduction in all manifestations of asymptomatic ischemia during ambulatory electrocardiographic monitoring (2.3 versus 1.0 episodes/24 hr; mean duration of ischemia per 24 hours, 43.6 versus 5.7 minutes; both p less than 0.0001). Diltiazem's reduction of the frequency of episodes compared with placebo (2.3 versus 1.9 episodes/24 hr) was associated with a trend (p = 0.08) in the protocol-completed analysis and with a significant reduction in the intent-to-treat analysis (p = 0.03). Nifedipine had no significant effect on any measured variable of ambulatory ischemia. The dosages of medication used may have been excessive for some patients, and a more beneficial effect may have been evident at a lower dose. In contrast to the marked effects of the active agents on ambulatory asymptomatic ischemia, the effects on exercise performance and angina pectoris were slight. The active agents modestly improved treadmill exercise duration time until 1 mm ST segment depression (3%), and only propranolol and diltiazem had significant effects. Only diltiazem significantly prolonged the total exercise time. Anginal frequency was significantly decreased by both propranolol and diltiazem.(ABSTRACT TRUNCATED AT 400 WORDS)