title: Identification of a secondary peak in myocardial infarction onset 11 to 12 hours after awakening: the Cardiac Arrhythmia Suppression Trial (CAST) experience.
abstract: OBJECTIVE
  The purpose of this study was to assess the relation between the time of awakening and the time of onset of acute myocardial infarction.
  
  
  BACKGROUND
  Previous investigation has shown the onset of symptoms of acute myocardial infarction to have a primary peak 1 to 2 h after awakening. In studies not corrected for time of awakening, there appears to be a late afternoon/early evening peak, but data correlating the onset of symptoms with awakening have been limited by small numbers of patients, perhaps precluding identification of a secondary peak.
  
  
  METHODS
  In the Cardiac Arrhythmia Suppression Trial (CAST), 3,549 patients had a documented myocardial infarction and entered antiarrhythmic drug titration. Of these, 3,309 had data on the onset of symptoms relative to the time of awakening and form the basis of this report.
  
  
  RESULTS
  A total of 870 patients (26.3%) were awakened by symptoms. Of the remaining 2,439 patients who were not awakened by symptoms, 798 (32.7%) experienced the onset of symptoms in the 1st 4 h after awakening (with the highest number in the 1st h), after which the incidence of symptom onset decreased in a linear fashion, with a secondary peak 11 to 12 h after awakening. Both peaks are statistically significant. A similar pattern was seen in most of the subgroups examined (based on age, gender and various other demographic characteristics).
  
  
  CONCLUSIONS
  Analysis of the very large CAST data base confirms the relation between awakening and onset of symptoms of myocardial infarction, suggesting involvement of the morning catecholamine surge. A secondary peak in symptom onset, occurring 11 to 12 h after awakening, is a new observation and may relate to ingestion of the evening meal or other trigger factors concentrated in those hours.
authors.affiliation: Department of Medicine, Baltimore Department of Veterans Affairs Medical Center, Maryland 21218.
authors.forename: R W
authors.initials: RW
authors.lastname: Peters
authors.forename: R G
authors.initials: RG
authors.lastname: Zoble
authors.forename: P R
authors.initials: PR
authors.lastname: Liebson
authors.forename: Y
authors.initials: Y
authors.lastname: Pawitan
authors.forename: M M
authors.initials: MM
authors.lastname: Brooks
authors.forename: M
authors.initials: M
authors.lastname: Proschan
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001145:Arrhythmias, Cardiac / Q000188:drug therapy / Q000209:etiology / Q000517:prevention & control; D015982:Bias; D002395:Catecholamines / Q000502:physiology; D002940:Circadian Rhythm; D016903:Drug Monitoring; D004435:Eating; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000145:classification / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology*; D012189:Retrospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D011795:Surveys and Questionnaires; D013997:Time Factors; D014851:Wakefulness
chemical_list: D000889:Anti-Arrhythmia Agents; D002395:Catecholamines