*2.2.1 Fast resting heart rate*

Several clinical and epidemiological reports have suggested that fast resting HR, as a marker of sympathetic nervous system and RAS overactivity, not only is a powerful independent predictor of CVD, but also of all-cause mortality. Resting faster HR could be associated, through oxidative stress and subsequent inflammation, with development of atherosclerosis, progression of heart failure, and enhancement of myocardial ischemia or infarction [31]. In a cross-sectional study of Congolese aircrew from both African and Caucasian origin, the proportion of subjects with a faster resting HR was of the same magnitude as the 6.8% observed in a normative sample from the First U.S. National Health and Nutrition Examination Survey (NHANES) I data [32]. It was nearly five times more frequent in flight than in cabin crew.
