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Differing circadian patterns of symptom onset in subgroups of patients with acute myocardial infarction
A Hjalmarson1, E A Gilpin, P Nicod
1Division of Cardiology, University of California, San Diego, La Jolla 92093.
Insights
Acute myocardial infarction onset shows circadian variation, with morning peaks. Specific patient subgroups, like those with heart failure or non-Q wave infarction, exhibit distinct onset patterns, influencing overall trends.
Area of Science:
- Cardiology
- Chronobiology
Background:
- Circadian variation in acute myocardial infarction (AMI) onset is documented.
- Subgroup analyses of these variations are limited.
- Understanding these patterns may reveal pathophysiologic insights.
Purpose of the Study:
- To investigate if specific clinical subgroups exhibit different circadian patterns of AMI onset.
- To determine how these subgroup patterns contribute to overall AMI onset peaks.
Main Methods:
- Analysis of symptom onset time in 4,796 patients with documented AMI.
- Subgroup analyses based on clinical characteristics: congestive heart failure, non-Q wave infarction, age >70, smokers, diabetics, women, beta-blocker use, and prior myocardial infarction.
Main Results:
- Overall AMI onset peaked in the morning (6:01 AM–12:00 noon) and evening.
- Patients with congestive heart failure or non-Q wave infarction showed a pronounced evening peak.
- Patients >70, smokers, diabetics, women, and those on beta-blockers had two near-equal peaks.
- Patients with prior myocardial infarction displayed no distinct onset peaks.
Conclusions:
- Specific patient subgroups demonstrate unique circadian patterns of acute myocardial infarction onset.
- These variations in subgroups contribute to the observed overall circadian rhythm of AMI.
- Identifying these patterns may aid in understanding AMI pathophysiology and timing of interventions.
Abstract:
Circadian variation of the onset of acute myocardial infarction has been noted in many studies and may carry important pathophysiologic implications. However, only a few previous studies have attempted subgroup analyses. In 4,796 patients with documented acute myocardial infarction, the time of symptom onset was recorded. As in other studies, the peak of onset occurred in the morning from 6:01 AM to 12:00 noon, and 28% of the population (1.16 times the average percentage for the other time periods) experienced symptom onset in that period (p less than 0.001). There was a second, lower peak (25%) in the evening between 6:01 PM and 12:00 midnight, which was also observed in some previous studies. We sought to determine whether or not the presence of subgroups with specific clinical characteristics would exhibit different patterns and thereby contribute to these peaks in the overall population. In patients with a history of congestive heart failure (n = 606) or with non-Q wave infarction (n = 832), a pronounced peak (29%) occurred only in the evening. Two nearly equal peaks were observed in patients older than 70 years of age (n = 1,422), smokers (n = 2,057), diabetics (n = 767), women (n = 1,213), and patients taking beta-blocking drugs (n = 847). Finally, in patients with a previous myocardial infarction (n = 1,104), no peaks were observed.(ABSTRACT TRUNCATED AT 250 WORDS)