Circadian Rhythm of Heart Rate Variability in Ischemic Heart Disease with or without Diabetes Mellitus

Yukihiro Fujimoto, Yuji Hirokane, Masaharu Fukuki, Shigemasa Hirata, Akira Hoshio, Yasushi Tanaka, Chiaki Shigemasa and Hiroto Mashiba*

First Department of Internal Medicine, Faculty of Medicine, Tottori University, Yonago 683 and *Kure Kyosai Hospital, Kure 737, Japan

We evaluated the clinical significance of heart rate variability (HRV) in ischemic heart disease (IHD) patients with or without diabetes mellitus (DM). One hundred and twenty-one patients were classified into 5 groups according to the angiographic severity of IHD (groups of severe IHD with or without DM, groups of mild IHD with or without DM and control group). HRV was evaluated using the spectral variables of all frequency (AF), low frequency (LF) and high frequency (HF) components and LF/HF ratio on Holter recordings. Only the HRV (AF, LF and HF components) in the severe IHD with DM group was lower than that in the control group, but the LF/HF ratio was not significantly different among the 5 patient groups. With regard to the circadian rhythm of HRV, AF and LF components in the severe IHD with DM group were significantly decreased all day and the HF component was decreased during the daytime and around midnight, while the LF/HF ratio was lower in the early morning. In contrast, these parameters of circadian HRV in severe IHD patients without DM showed no significant decrease at any time. During the follow-up period, 3 IHD patients without DM died as a result of acute myocardial infarction with no decrease in HRV, while 3 IHD patients with DM died due to sudden death or heart failure and had decreased HRV. These results suggest that only the severe IHD with DM group had a decreased HRV which was related to cardiac death.

Key words: circadian rhythm; diabetes mellitus; heart rate variability; ischemic heart disease

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