Turk Kardiyol Dern Ars. 2008; 36(6): 368-375

High levels of high-sensitivity C-reactive protein and impaired autonomic activity in smokers

Ömer Alyan¹, Fehmi Kaçmaz², Özcan Özdemir³, Zülküf Karahan¹, Tuncay Taşkesen¹, Hikmet İyem⁴, Sait Alan¹, Aziz Karadede¹, Erdoğan İlkay^5
1Department Of Cardiology, Dicle University, Diyarbakir, Turkey
²Bingol State Hospital, Cardiology Clinic, Bingol, Turkey
³Akay Hospital, Cardiology Clinic, Ankara, Turkey
⁴Department Of Cardiovascular Surgery, Dicle University, Diyarbakir, Turkey
⁵Mesa Hospital, Cardiology Clinic, Ankara, Turkey

OBJECTIVES
We investigated the relationship between high sensitivity C-reactive protein (hs-CRP) activity and autonomic nervous activity using heart rate variability in smokers.

STUDY DESIGN
The study consisted of 136 healthy subjects, including 66 smokers (35 women, 31 men; mean age 36 years) and 70 nonsmokers (43 women, 27 men; mean age 34 years). Serum samples were collected from all the subjects. Three-channel, 24-hr Holter monitoring was performed to derive the mean heart rate, standard deviation of normal NN intervals (SDNN), standard deviation of 5-minute mean NN intervals (SDANN), root mean square differences of successive NN intervals (RMSSD), high- (HF) and low- (LF) frequency power components, and the LF/HF ratio.

RESULTS
In smokers, the mean duration of smoking was 13.6±8.2 years (range 3 to 45 years), and the mean number of cigarettes consumed per day was 16.3±7.1 (range 5 to 40). Smokers exhibited significantly higher mean heart rate, hs-CRP and fibrinogen levels, mean platelet volume, white blood cell count, LF, and LF/HF ratio, with significantly lower SDNN, SDANN, RMSSD, and HF values. In smokers, hs-CRP was correlated with the number of cigarettes consumed per day, duration of smoking, fibrinogen level, mean platelet volume, white blood cell count, LF, and LF/HF ratio, and inversely correlated with HF, SDNN, and SDANN. Even smoking a single cigarette resulted in an acute, 0.07-fold increase in the hs-CRP level (p<0.0001). In linear regression analysis, both the number of cigarettes consumed per day (=0.52, p=0.011) and duration of smoking (=0.073, p<0.0001) had an independent effect on the hs-CRP level.

CONCLUSION
Smoking both impairs the sympathovagal balance and increases the hs-CRP activity in otherwise healthy smokers, the combination of which would probably contribute to a higher rate of cardiovascular events.

Keywords: C-Reactive protein/analysis, electrocardiography, heart rate/physiology, risk factors; smoking/adverse effects; sympathetic nervous system/physiology.

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