CHAT (Circadian Hyper-Amplitude-Tension) and CSDD-HR (Circadian Standard Deviation Deficit of Heart Rate): Separate, synergistic vascular disease risks?

Adverse vascular outcomes recorded during 6 years were related to abnormalities in the variability of blood pressure and heart rate of 297 patients. Each was monitored for 48 hours at 30-min intervals at the beginning of the study. Patients with circadian amplitude of blood pressure and a 48-hour standard deviation of heart rate within acceptable limits constituted the reference group. As compared to the reference group, patients with either too large circadian amplitude of blood pressure (CHAT) or too low a standard deviation of heart rate had an increase in cardiovascular disease risk. When both conditions coexisted, the increase in risk was larger than the addition of both risks. CHAT and reduced heart rate variability are two separate synergistic disease risk conditions, detected by a chronobiologic approach, even when they occur within the conventional normal range.