[The clinical relevant factors of the myocardial ischemic threshold].
The myocardial ischemic threshold (heart rate at the onset of ischemia) was assessed in 92 patients with coronary heart disease. The highest myocardial ischemic threshold (HMIT) ranged from 83 to 163 (122 +/- 18) beats/min usually happened during activities at the daytime. The lowest myocardial ischemic threshold (LMIT) ranged from 45 to 115 (82 +/- 17) beats/min usually happened when awaken early morning or asleep at night. The differences were statistically significant (P < 0.01). The mean variability of myocardial ischemic threshold (VMIT) was 30.22% (range from 8.2 to 51.2%). The variability was correlated positively with the number of ischemic episodes, negatively with LMIT, and larger in senior-aged group than in middle-aged group (P < 0.001). The authors suggest that LMIT and VMIT may be related to the severity of coronary lesions, coronary tonus, and the patients' prognosis, etc.
Lu
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First Affiliated Hospital, Zhejiang Medical University, Hangzhou.
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000787:Angina Pectoris / Q000503:physiopathology; D002940:Circadian Rhythm; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000503:physiopathology*; D011379:Prognosis