[Comparison of the circadian variation of the time of onset of acute myocardial infarction and of attack of vasospastic angina without significant stenosis].

Objectives: To study the involvement of vasospasm as the trigger of acute myocardial infarction without significant stenosis, the circadian variation of the time of onset of acute myocardial infarction was compared with that of vasospastic angina without significant stenosis.

Methods: The subjects consisted of 3 groups, 64 patients with acute myocardial infarction without significant stenosis, 101 patients with acute myocardial infarction with one vessel disease and 98 patients with vasospastic angina without significant stenosis. The times of onset of acute myocardial infarction and spontaneous attack of vasospastic angina were recorded and classified according to the 4 periods (0:00-6:00, 6:00-12:00, 12:00-18:00, 18:00-24:00) and the pattern of distribution was compared between the 3 groups.

Results: The time distribution of acute myocardial infarction without significant stenosis showed a double peaked pattern at 6:00-12:00 and 18:00-24:00 and was similar to the pattern of acute myocardial infarction with one vessel disease(p = 0.93). Only a single peak in 0:00-6:00 was found in the pattern of distribution of vasospastic angina without significant stenosis and differed significantly from acute myocardial infarction(p < 0.01).

Conclusions: The circadian variation of the time of onset of acute myocardial infarction was similar in patients with or without significant stenosis, and differed significantly from that in patients with vasospastic angina.