The 24-hour Holter ECG monitoring was performed in 79 patients with old myocardial infarction, 46 with anterior infarction and 33 with inferior infarction, and the daily profile of ventricular premature contractions (VPCs) prevalence was studied. Fifteen healthy subjects served as controls.The prevalence rate of VPCs in a day varied within a small range (mixed type) in patients with anterior infarction, while VPCs in patients with inferior infarction appeared more frequently during the daytime than at night (daytime type).The LV ejection fraction did not influence the daily profile of the VPC prevalence rate. VPCs tended to be more frequent during the night in patients under 60 years of age with anterior infarction, but the inferior infarction group of patients undergo mainly showed the daytime pattern. Complex VPCs including grade 3 or more of Lown's classificasion had a tendency to be more frequent in patients with the daytime type VPC profile than VPCs of less than grade 3 of Lown's classificasion.Grade 4 VPCs mainly appeared during daytime in both the anterior infarction and inferior infarction groups.These characteristic daily profiles of VPC prevalence suggest different mechanisms of VPCs between anterior infarction and inferior infarction, and would be of use for the medical treatment of VPCs.
24 hour Holter ECG monitoring
ventricular premature contraction