Transient myocardial ischaemia during ambulatory monitoring out of hospital in patients with chronic stable angina pectoris

Prevalence and prognostic implications of ST-segment deviations from ambulatory Holter monitoring after ST-segment elevation myocardial infarction treated with either fibrinolysis or primary percutaneous coronary intervention (a Danish Trial in Acute Myocardial Infarction-2 Substudy)

Ambulatory Holter monitoring has been shown to be useful in stratifying cardiovascular risk after acute myocardial infarction. However, it remains unclear whether ST-segment deviations might predict clinical outcomes in a population treated with primary percutaneous coronary intervention (PCI) compared with thrombolysis. Holter monitoring was initiated at discharge from ST-segment elevation myocardial infarction in 958 patients followed for 2,773 patient-years, randomized to immediate revascularization with either fibrinolysis (n=474) or PCI (n=484). The primary end point was all-cause mortality, and the secondary end point was a composite of death, reinfarction, and disabling stroke. The prevalences of ST-segment depression (STd) and ST-segment elevation (STe) were similar in patients treated with fibrinolysis or PCI (both p=NS). During follow-up, 58 patients died (primary PCI vs fibrinolysis hazard ratio 0.74, p=0.25). The secondary end point was reached in 113 patients (primary PCI vs fibrinolysis hazard ratio 0.66, p=0.03). In fibrinolysis-treated patients, mortality and the secondary end point were significantly higher in patients with STe (both end points p<0.001), an association that remained statistically significant after adjustment for age, gender, anterior infarction, beta-blocker treatment, left ventricular systolic function, and STd (p=0.03 and p=0.005, respectively). Significant associations were not observed for STd. In PCI-treated patients, there was no association between either STe or STd and outcome. In conclusion, immediate revascularization with PCI during STe myocardial infarction does not affect the subsequent prevalence of ST-segment deviation compared with fibrinolysis. However, although STe is an independent predictor of mortality and nonfatal major cardiovascular events in patients treated with fibrinolysis, it does not predict outcome after PCI, perhaps because of more complete revascularization.

The normal circadian pattern of blood pressure: implications for treatment

Blood pressure fluctuates over 24 h following a circadian rhythm that reaches a peak in the morning shortly after awakening. The onset of many acute cardiovascular and cerebrovascular events shows a synchronous cyclical pattern, with the highest incidence of morbidity and mortality in the early morning hours. Strong, although circumstantial, evidence suggests that the early morning surge in blood pressure may contribute to the onset of acute cardiovascular episodes. Sustained blood pressure control that blunts the early morning blood pressure surge may help to reduce the incidence of these events. Antihypertensive agents are needed that provide smooth and sustained blood pressure control for the full 24 h, including the risky early morning hours. The angiotensin II receptor blocker telmisartan given once daily, because of its long half-life and mechanism of action, is likely to confer benefit in terms of 24-h blood pressure control and may reduce cardiovascular risk at the time of greatest patient vulnerability.

Sleep-disordered breathing and myocardial ischemia in patients with coronary artery disease

STUDY OBJECTIVES

To examine the occurrence of nocturnal myocardial ischemia and its relationship to sleep-disordered breathing (apneas and oxygen desaturations) in randomly selected men and women undergoing coronary angiography because of angina pectoris.

DESIGN

An observational study using an overnight sleep study and Holter recording to examine disordered breathing (oxyhemoglobin desaturations > or = 4% and apnea-hypopneas), heart rates, and ST-segment depressions (> or = 1 mm, > or = 1 min).

SETTING

University Hospital, Umeå, a teaching hospital in northern Sweden.

PATIENTS

One hundred thirty-two men and 94 women referred for consideration of coronary intervention were randomly included, by lot.

RESULTS

ST-segment depressions occurred in 59% (134 of 226) of the patients, and nocturnal ST-segment depressions occurred in 31% (69 of 226). A ST-segment depression occurred within 2 min after an apnea-hypopnea or desaturation in 12% (27 of 226) of patients. This temporal association was seen in 19% of nocturnal ST-segment depressions (71 of 366), more frequently in men (p < 0.01) and in more severely disordered breathing (p < 0.001). Most of these ST-segment depressions were preceded by a series of breathing events: three or more apnea-hypopneas or desaturations or both in 70% (50 of 71).

CONCLUSION

Episodes of nocturnal myocardial ischemia are common in patients with angina pectoris. However, a temporal relationship between sleep-disordered breathing and myocardial ischemia is present only in a minority of the patients, but occurs more frequently in men and in more severely disordered breathing.

Transient myocardial ischemia during nifedipine therapy in stable angina pectoris, and its relation to coronary collateral flow and comparison with metoprolol

There are conflicting results concerning the anti-ischemic effect of nifedipine in patients with chronic stable angina. Therefore, the purpose of this study was to assess whether the anti-ischemic effect of nifedipine may be related to coronary collateral circulation. Forty-one patients with stable angina and coronary artery disease were randomized to a parallel double-blind study with nifedipine and metoprolol, and compared for effects on transient ischemic episodes during ambulatory electrocardiographic monitoring and exercise-induced ischemia. The effects were correlated to the presence of collateral circulation. In 17 patients, angiographically poor or no collateral flow was observed (group 1), and 24 had good collateral flow (group 2). Nifedipine was administered to 20 patients (8 in group 1, and 12 in group 2). In group 1, nifedipine reduced the frequency of total and asymptomatic ischemic episodes (p < 0.05), whereas significant increases in both total (p < 0.05) and silent (p < 0.01) ischemia were observed in group 2. Exercise variables were slightly improved (p = NS) during nifedipine therapy in group 1, and slightly worsened (p = NS) in group 2. Reflex tachycardia was not observed at either the onset of transient ischemia out of the hospital or exercise-induced ischemia. This was in contrast with the effect in 21 patients treated with metoprolol (9 in group 1, and 12 in group 2) where significant reductions were observed in the frequency of both total (p < 0.01) and silent (p < 0.01) ischemia in both groups. Furthermore, a beneficial effect was observed on all exercise variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of circadian variation by combined antianginal therapy with suppression of morning and evening increases in transient myocardial ischemia

The circadian variation of total ischemic activity was examined during 3289 hours of ambulatory ECG monitoring in 101 patients with stable angina pectoris and proved coronary artery disease, who were not receiving any prophylactic antianginal therapy. The 101 patients displayed 411 episodes of ischemia, 312 (76%) of which were silent; a circadian rhythm was noted for the occurrence of total and silent ischemia. Thirty-eight percent of the ischemic episodes occurred between 6 AM and 12 noon, and total and silent ischemia were significantly more frequent during this period compared with the other three 6-hour periods (p less than 0.01); a lesser peak was noted in the evening. The effects of metoprolol and combined therapy with metoprolol and nifedipine on the circadian variation of ischemic activity were studied in two subgroups of patients in a random, double-blind study design (31 patients receiving metoprolol and 42 receiving combined therapy). During therapy with metoprolol the morning increase in ischemic activity was attenuated, and the highest frequency of ischemia was then noted in the evening (6 AM to 12 noon compared with 6 PM to 12 midnight; p less than 0.05). Combined therapy abolished the morning peak as did metoprolol monotherapy, but even the evening increase in ischemic activity was attenuated (p less than 0.05). The diurnal distribution of the mean heart rate at the onset of ischemia, when patients were off therapy, showed a morning increase similar to the increase in ischemic activity but no second peak in the evening.(ABSTRACT TRUNCATED AT 250 WORDS)