Association between 24-hour ambulatory heart rate and arterial stiffness

Clinical and experimental studies point to a positive association between carotid-femoral pulse wave velocity (PWVcf) and casual heart rate. However, an association with 24-h ambulatory heart rate has never been investigated. Twenty-four hour ambulatory heart rate and PWVcf (automatic computerised technique) were simultaneously measured in 213 subjects with untreated mild-to-moderate essential hypertension. It was found that mean ambulatory heart rate was higher in women than in men but the difference reached statistical significance only in those below 50 years of age during night-time measurements. As well as age and blood pressure, 24-h ambulatory heart rate was also an independent factor influencing PWVcf. Independent of gender, the relationship between PWVcf and ambulatory heart rate was stronger in patients over 50 years of age. Casual heart rate was not a significant determinant of PWVcf in this population. In conclusion, ambulatory heart rate contribution to explain pulse wave velocity is more important than casual heart rate. The relationship between 24-h heart rate and pulse wave velocity is stronger for subjects older than 50 years of age independent of gender.