Ambulant myocardial ischemia and its prognostic implications

Comparison of subgroups assigned to medical regimens used to suppress cardiac ischemia (the Asymptomatic Cardiac Ischemia Pilot [ACIP] Study)

This report focuses on the subset of 235 patients from the Asymptomatic Cardiac Ischemia Pilot (ACIP) study receiving randomly assigned medical therapy to treat angina and suppress ischemia detected on ambulatory electrocardiography: 121 patients received the sequence of atenolol and nifedipine, and 114 diltiazem and isosorbide dinitrate. After 12 weeks of therapy, the primary end point (absence of ambulatory electrocardiographic (ECG) ischemia and no clinical events) was reached in 47% of atenolol/nifedipine- versus 31% of diltiazem/isosorbide dinitrate-treated patients (adjusted p = 0.03). A trend to increased exercise time to ST depression was seen in the atenolol and nifedipine versus diltiazem and isosorbide dinitrate regimens (median treadmill duration 5.8 vs 4.8 minutes; p = 0.04). However, when adjusted for baseline imbalances in ambulatory ECG ischemia, the 2 medical combinations were similar in suppression of ambulatory ECG ischemia. In both medication regimens, an association between mean heart rate and ischemia on ambulatory electrocardiography after 12 weeks of treatment was observed so that patients on either regimen with a mean heart rate > 80 beats/min had ischemia detectable almost twice as often as those with a mean heart rate < 70 beats/min (p < 0.001).

Can nitroglycerin convert effort-induced angina in men into silent myocardial ischemia?

The relief of anginal pain with nitroglycerin may not correspond to the disappearance of ischemia. To evaluate the possible lack of the elimination of ischemia with sublingual nitroglycerin, we studied 25 male patients with stable angina pectoris who underwent exercise stress testing with recording of blood pressure, pulse, and ST-segment displacement. The stress test was repeated 30 minutes after administration of 0.4 mg of sublingual nitroglycerin. All 25 patients had angina and ischemic ST-segment changes in the first stress test. On repeat stress testing, 15 patients had angina and ST-segment changes, 2 patients had angina but no ST-segment changes, and 4 patients had no ST-segment changes and no angina. Four patients, however, had no angina but persistent ischemic ST-segment changes suggesting that angina was converted into silent ischemia. The mean exercise duration was 311 +/- 66 seconds before and 421 +/- 81 seconds after the nitroglycerin test. Peak heart rate and systolic blood pressure before the nitroglycerin stress test were 109 +/- 18 and 155 +/- 23 mm Hg; in the repeat stress test, they increased to 123 +/- 21 and 162 +/- 20 mm Hg, respectively.

Trimetazidine: a new concept in the treatment of angina. Comparison with propranolol in patients with stable angina. Trimetazidine European Multicenter Study Group

1. Trimetazidine has a direct anti-ischaemic effect on the myocardium without altering the rate x pressure product or coronary blood flow. 2. The effects of trimetazidine (20 mg three times daily) were compared with those of propranolol (40 mg three times daily) in a double-blind parallel group multicentre study in 149 men with stable angina. 3. Reproducibility of exercise performance was verified during a 3 week run-in placebo washout period. All patients had > 1 mm ST-depression on exercise test. 4. After 3 months, similar anti-anginal efficacy was observed between the trimetazidine (n = 71) and propranolol (n = 78) groups. No significant differences were observed between trimetazidine and propranolol as regards anginal attack rate per week (mean difference P-TMZ: 2; 95% CI: -4.4, 0.5) and exercise duration (mean difference P-TMZ: 0 s; 95% CI: -33, 34) or time to 1 mm ST segment depression (mean difference P-TMZ: 13 s; 95% CI: -24, 51). Heart rate and rate x pressure product at rest and at peak exercise remained unchanged in the trimetazidine group but significantly decreased with propranolol (P < 0.001 in all cases). With both drugs there was a trend to decreased ischaemic episodes in the 46% patients who experienced ambulatory ischaemia on Holter monitoring. Six patients stopped trimetazidine and 12 propranolol. Of these, five in each group were withdrawn because of deterioration in cardiovascular status. 5. The results suggest that trimetazidine and propranolol at the doses studied have similar efficacy in patients with stable angina pectoris.(ABSTRACT TRUNCATED AT 250 WORDS)

Anipamil prevents ST depression in patients with stable angina pectoris

The purpose of this study was to examine the 24-hour antiischemic efficacy of once-a-day anipamil compared to placebo in the treatment of patients with stable angina. The study was designed as a double-blind, placebo-controlled crossover study with an initial 3 week single-blind placebo period. The patients received anipamil 80 mg once daily, anipamil 160 mg once daily, and placebo in a randomized order. At the end of each treatment period the patients underwent 24-hour ambulatory ECG recording. Nineteen patients were included, all with typical stable angina pectoris for at least 2 months, exercise test with > or = 0.10 mV horizontal or down-sloping ST-segment depression and limited by angina pectoris, and at least 10 attacks of angina pectoris in the initial single-blind placebo period. During the placebo period, a total duration of transient myocardial ischemia > or = 0.10 mV during the 24-hour ambulatory ECG monitoring period was 2263 minutes, 75% of which were asymptomatic. Anipamil 80 mg and 160 mg significantly reduced the duration of episodes to 712 minutes (p < 0.001), with 87% asymptomatic, and to 913 minutes (p > 0.001), with 92% asymptomatic, respectively. In conclusion, anipamil given once a day is an effective 24-hour antiischemic drug in the treatment of transient myocardial ischemia.

Discordance between effects of anti-ischemic therapy on ambulatory ischemia, exercise performance and anginal symptoms in patients with stable angina pectoris. The Angina and Silent Ischemia Study Group (ASIS)

OBJECTIVES

We sought to define the extent to which the therapeutic efficacy of three single-drug regimens on ambulatory ischemia paralleled efficacy on other clinical manifestations of ischemia, specifically exercise test performance and anginal symptoms.

BACKGROUND

Some studies have shown that the presence and severity of ambulatory ischemia are predictive of anginal symptoms and exercise test performance, whereas other studies have not. Less is known about effects of antianginal treatment and whether response to therapy for one clinical manifestation reflects therapeutic responses for other clinical manifestations.

METHODS

We studied 50 patients in the Angina and Silent Ischemia Study who had documented coronary disease, an exercise test positive for ischemia, the presence of ambulatory and asymptomatic ischemia on ambulatory electrocardiographic (ECG) Holter monitoring and stable anginal symptoms. Patients received maximally tolerated doses of sustained release propranolol (mean 293 mg/day), sustained release diltiazem (mean 350 mg/day), nifedipine (mean 79 mg/day) and placebo, each for 2-week periods in a double-blind, crossover fashion. Patients' responses to treatment were assessed by 48-h ambulatory ECG monitoring, exercise test (standard Bruce protocol) and diaries of angina. Levels of efficacy for each agent and for each clinical measure were compared using Spearman correlation analysis.

RESULTS

With placebo there was no correlation among the frequency of ischemic episodes by ambulatory ECG monitoring, exercise time to 1.0-mm ST segment depression or frequency of anginal episodes. Furthermore, for a given patient the efficacy of each active medication in reducing ambulatory ischemia was not correlated with response in anginal symptoms or exercise test performance (r = -0.21 to 0.24, p = NS). Within each of these clinical measures, efficacy of one drug was more strongly correlated with efficacy of another drug (r = 0.64 to 0.81 for ambulatory ischemia, 0.48 to 0.56 for exercise test performance and 0.16 to 0.54 for anginal symptoms).

CONCLUSIONS

Different measures of ischemia, specifically ambulatory ischemia assessed by ambulatory ECG monitoring, exercise performance on exercise test and anginal symptoms, are independent. Efficacy for each clinical end point must be assessed separately when considering response to drug treatment.

Daily life ischemia and nitrate therapy

Daily life ischemia has generated considerable interest because most of it is silent and associated with increased risk of adverse outcome. Coronary vasomotion, as well as increases in myocardial oxygen demand, seem important in the pathogenesis of this form of ischemia, so treatment with nitrates seems rational. Administration of sublingual nitroglycerin hourly, over 12 hours, was shown to decrease both silent and painful ischemic episodes in patients with effort angina. Subsequently, isosorbide dinitrate or mononitrate, given either as an intravenous infusion or orally, was shown to decrease both silent and painful ischemic episodes in patients with unstable rest angina and in those with severe angina. More recently, 6 studies have reported using transdermal nitroglycerin for daily life ischemia. Three of these reported open-label uncontrolled observations and suggested that ischemia frequency may be reduced approximately 60-80% during treatment with doses of 10-30 mg/day, with a duration of treatment ranging from 1 hour to 14 days. In 2 of these reports the duration of ischemia also decreased. The other 3 studies were randomized, double-blind, placebo-controlled studies with a total enrollment of 86 patients. These studies provided mixed results. One suggested that evidence for partial tolerance develops within 1 day of treatment, using large continuous or intermittent doses (mean, 52 mg/day). Another suggested that no tolerance develops to intermittent dosing (18 mg/16 hr out of 24 hr) during exercise testing but no effect is seen on daily life ischemia. The remaining study suggested that tolerance does not develop using small doses (15 mg/day) continuously over 14 days for ischemia during daily life, and that this response is different from that observed using the calcium antagonist nifedipine. These limited observations and conflicting results underscore a need for additional larger controlled trials, employing topical nitrate therapy in low intermittent doses for daily life ischemia.

Anti-ischemic effects of atenolol versus nifedipine in patients with coronary artery disease and ambulatory silent ischemia

The anti-ischemic effects of atenolol and nifedipine were compared in a randomized double-blind crossover manner in 24 patients with stable exertional angina and transient silent ischemia during ambulatory electrocardiographic (ECG) monitoring. Both atenolol and nifedipine were effective (p less than 0.005) in reducing the average number and duration of transient ischemic events, but therapy with atenolol was associated with a significantly greater reduction in the mean number (p less than 0.05) and duration (p less than 0.01) of silent ischemic events. Analyses of the silent ischemic activity during the morning hours revealed that only therapy with atenolol produced a significant reduction in the average duration per patient (139 +/- 54 vs. 1,609 +/- 468 s, p less than 0.01) and in the average duration of silent ischemia per event between 6 AM and 12 noon (62 +/- 21 vs. 208 +/- 24 s, p less than 0.005). There were fewer adverse experiences during therapy with atenolol. These results show that although both atenolol and nifedipine are effective in reducing silent ischemic events, treatment with atenolol is associated with significantly greater efficacy, particularly on the morning surge of silent myocardial ischemia.