the importance of physical or mental stress in triggering onset of coronary thrombosis is supported by the findings that 1 ) the frequencies of onset of myocardial infarction , sudden cardiac death , and stroke show marked circadian variations with parallel increases in the period from 6:00 am to noon , 2 ) transient myocardial ischemia shows a similar morning increase , and episodes are often preceded by mental or physical triggers , 3 ) a ruptured atherosclerotic plaque , often nonobstructive by itself , lies at the base of most coronary thrombi , 4 ) a number of physiologic processes that could lead to plaque rupture , a hypercoagulable state or coronary vasoconstriction , are accentuated in the morning , and 5 ) aspirin and beta-adrenergic blocking agents , which block certain of these processes , have been shown to prevent disease onset .
C0027051
myocardial infarction
C0004057
aspirin