Differing circadian patterns of symptom onset in subgroups of patients with acute myocardial infarction.

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<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%o) 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 ,B-blocking drugs (n = 847). Finally, in patients with a previous myocardial infarction (n = 1,104), no peaks were observed. In a subgroup of patients (n = 1,084) free of the most important modifying factors, there was a single very pronounced late morning peak (32%, 1.39 times the average percentage for the other time periods, p<0.001) without evidence of a second evening peak. It is concluded that marked differences in diurnal patterns of myocardial infarction onset occur in subgroups of patients with modifying factors, particularly non-Q wave infarction, smoking, ,B-blocker use, diabetes, prior congestive heart failure, and prior myocardial infarction. The circadian pattern observed in a given total population reflects the contributions of these subgroups. (Circulation 1989;80:267-275) A circadian variation in the frequency of onset of acute myocardial infarction has been described in a number of studies during the past 25 years.1-8 Most show an increased onset in the morning with a peak incidence between 6:00 AM and 12:00 noon, although a secondary peak in the late evening has also been reported in some studies.1-3,5-7 A circadian variation in onset of other *All editorial decisions for this article, including selection of reviewers and the final decision, were made by a guest editor. This procedure applies to all manuscripts with authors from the

Early Morning Attenuation of Endothelial Function in Healthy Humans

“…9 Insofar as plasma norepinephrine levels are able to detect changes in sympathetic activity, and in agreement with data from Schofl et al, 42 we did not observe any increase in norepinephrine, blood pressure, or heart rate in the morning. A further limitation relates to data from Hjalmarson et al, 43 who observed a lower second peak in the incidence of myocardial infarction in patients with congestive heart failure, those with non-Q-wave infarction, smokers, and diabetics. Our study was not designed to address this secondary peak, and we cannot draw inferences regarding the potential mechanism involved.…”

Effects on heart rate variability of metoprolol supplementary to ongoing ACE-inhibitor treatment in Type I diabetic patients with abnormal albuminuria

“…Several studies suggest that in Type I diabetic patients with autonomic neuropathy the impaired diurnal blood pressure variation is associated with a relative nocturnal predominance of sympathetic activity [4,5]. This might represent a risk factor for cardiovascular disease and a possible explanation for the increased incidence of myocardial infarction during the night in diabetic patients [6]. Theoretically, treatment with a drug that restrains the predominant sympathetic activity might yield protection to the heart.…”

Circadian Variation of the Onset of Acute Myocardial Infarction in the Osaka Area, 1998-1999

“…[7][8][9][10] Analysis of this circadian variations is important to clarify the triggering mechanisms of AMI.Although the precise underlying mechanisms of the circadian variation of AMI are still unclear, the morning peak appears to be associated with surges of blood pressure, 11-13 neurohumoral factors 14,15 and platelet aggregability; [16][17][18] that is, it appears to be associated with an inherent biologic rhythm. However, the second peak in the evening is more associated with socioeconomic factors, such as the timing of the evening meal, 19 mental stress 20-22 and overtime work, 23 but it is unclear which population is more susceptible to the morning surge or to the nighttime socioeconomic factors.…”

“…[7][8][9][10] Analysis of this circadian variations is important to clarify the triggering mechanisms of AMI.…”