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Circadian variation of ischemic threshold in patients with chronic stable angina
1Department of Internal Medicine, Nippon Medical School, Sendagi, Bunkyo-ku, Tokyo, Japan.
Insights
Chronic stable exertional angina patients experienced more ischemic attacks in the morning. The ischemic threshold was lower in the morning, suggesting different causes for myocardial ischemia attacks throughout the day.
Area of Science:
- Cardiology
- Circadian Biology
- Ischemic Heart Disease
Background:
- Chronic stable exertional angina is a common manifestation of coronary artery disease.
- Understanding the circadian variation in ischemic events is crucial for optimizing patient management.
- Previous studies have indicated diurnal patterns in cardiovascular events, but specific thresholds require further investigation.
Purpose of the Study:
- To investigate the circadian variation of the ischemic threshold in patients with chronic stable exertional angina.
- To identify specific time zones associated with increased risk of ischemic attacks.
- To explore potential differences in the pathogenesis of myocardial ischemia based on time of day.
Main Methods:
- Prospective study involving 51 patients with documented coronary artery disease.
- Continuous electrocardiographic monitoring using Holter monitors to detect ischemic attacks.
- Analysis of ischemic attack frequency, ST-segment depression magnitude and duration, and ischemic threshold at different times of day.
Main Results:
- The peak time for ischemic attacks was observed between 8 a.m. and 9 a.m.
- No significant differences were found in the frequency, magnitude, or duration of ischemic attacks between the 6-9 a.m. and 0-3 p.m. time zones.
- A significantly lower ischemic threshold was recorded in the morning compared to the afternoon.
Conclusions:
- The findings suggest a circadian variation in the ischemic threshold for patients with chronic stable exertional angina.
- The pathogenesis of myocardial ischemia may differ between morning and afternoon ischemic attacks.
- These results can inform the development of time-specific therapeutic strategies for managing angina.
Abstract:
Circadian variation of ischemic threshold in chronic stable exertional angina was determined in 51 patients with documented coronary artery disease from the Holter monitor results. The peak favored time zones of ischemic attacks were 8 a.m. and 9 a.m. There was no difference in frequency of ischemic attacks, magnitude of ST-segment depression, or duration of ST-segment depression between the two time zones for ischemic attacks, 6-9 a.m. and 0-3 p.m., but the ischemic threshold was lower in the morning than in the afternoon. These observations suggest that the pathogenesis of ischemic attacks differs from one time zone to the other and is considered helpful in planning therapeutic strategies for myocardial ischemia.