Circadian Variation in the Frequency of Onset of Acute Myocardial Infarction

Abstract

To determine whether the onset of myocardial infarction occurs randomly throughout the day, we analyzed the time of onset of pain in 2999 patients admitted with myocardial infarction. A marked circadian rhythm in the frequency of onset was detected, with a peak from 6 a.m. to noon (P less than 0.01). In 703 of the patients, the time of the first elevation in the plasma creatine kinase MB (CK-MB) level could be used to time the onset of myocardial infarction objectively. CK-MB-estimated timing confirmed the existence of a circadian rhythm, with a three-fold increase in the frequency of onset of myocardial infarction at peak (9 a.m.) as compared with trough (11 p.m.) periods. The circadian rhythm was not detected in patients receiving beta-adrenergic blocking agents before myocardial infarction but was present in those not receiving such therapy. If coronary arteries become vulnerable to occlusion when the intima covering an atherosclerotic plaque is disrupted, the circadian timing of myocardial infarction may result from a variation in the tendency to thrombosis. If the rhythmic processes that drive the circadian rhythm of myocardial-infarction onset can be identified, their modification may delay or prevent the occurrence of infarction.

Increased arterial stiffness in obstructive sleep apnea: a systematic review

“…69 Nevertheless, it should be noted that this effect still bears importance, as most cardiovascular events take place in the morning. 83,84 CONCLUSION To the best of our knowledge this is the first systematic review on the effect of OSA on arterial stiffness. We have reviewed results from 24 studies evaluating the effect of OSA on arterial stiffness.…”

“Summer Shift”: A Potential Effect of Sunshine on the Time Onset of ST‐Elevation Acute Myocardial Infarction

“…Therefore, we decided to investigate (Figure 2) whether the clear overall decrease of STEMI onset during summer (summer nadir) would also affect the circadian peak during the diurnal hours (second and third quarter of the day, 6:00 to 18:00) with respect to the nocturnal hours (the fourth and first quarter of the day, 18:00 to 6:00). The choice to select these 2 precise intervals (6:00 to 18:00 and 18:00 to 6:00) was motivated by the fact that this subdivision was largely accepted in previous studies, and in general, higher incidence of STEMI occurs during the second and third quarters of the day 4, 5, 6, 7, 8, 9. Hence, we decided to measure the percentage difference (Δ%) of STEMI onset during the 6:00 to 18:00 (diurnal) interval with respect to the 18:00 to 6:00 (nocturnal) interval using the following formula:$\mathrm{\Delta }\%=\frac{false(\#\text{STEMI in 6 to 18 time interval)}-false(\#\text{STEMI in 18 to 6 time interval)}}{(\#\text{STEMI in 18 to 6 time interval)}}\times 100$ …”

“…Triggers that explain this acute transition from asymptomatic coronary plaques to acute thrombosis and STEMI are still under investigation 2, 3. The fact that onset of STEMI has a circadian rhythm with a peak during diurnal hours has been well described 4, 5, 6, 7, 8, 9, 10, 11, 12. A seasonal pattern13 in the occurrence of STEMI was also found with a salient peak of cases in the winter months and a marked nadir of cases in the summer months 14, 15, 16, 17, 18, 19.…”

Prognostic significance of blood pressure measured on rising

“…This would be consistent with the observation of a higher incidence of cardiovascular complications between 7 am and 11 am in the morning. 15,16 Another possibility is that this value reflects the activity of the sympathetic system where hyperactivity is known to increase the risk of cardiovascular events. 17,18 However, in this case, the link with cardiovascular complications should be at least as strong with heart rate as with arising BP, which we did not observe in our population.…”