Night-to-Day Ratio Specified by 24-hour Blood Pressure Monitoring, Arterial Stiffness and Cardio-Ankle Vascular Index as Predictive Factors of Cardiovascular Risk

This study compares the interrelationships among different methods of determining predictive factors of cardiovascular risk: the Night-to-Day ratio (ND-R), Ambulatory Arterial Stiffness Index (AASI), Cardio-Ankle Vascular Index (CAVI), and Ankle-Brachial Index (ABI). A total of 8120 blood pressure measurements were obtained from 280 24h-ABPM records (29 values per daily record) of 20 patients who each provided two 7-day/24-hour monitoring sessions. For each of the two 7-day-24h-ABPM records, the ND-R and AASI were determined. CAVI and ABI were always examined at the beginning of each 7-day-24h-ABPM session. All 20 patients (12 men; 8 women; mean age 57±2.1 yrs; mean BMI 29.3±1.69 kg/m²; mean left ventricle ejection fraction 53±3.8 %) had chronic ischemic coronary artery disease. The correlation coefficients did not exceed 0.318. ND-R of SBP showed the highest methodological sensitivity, identifying 65 % of patients at increased risk, compared to 57.5 % for ND-R of DBP, 23.7 % for CAVI, and 2.5 % for AASI (up to 27.5 % by evaluating individual days). The different cardiovascular risk assessment methods (ND-R, AASI, CAVI and ABI) cannot be substituted for one another. No risk was demonstrated using ABI. Repeating the 7-day-24h-ABPM approximately 1 year apart (unless there is a change in medication or in clinical symptoms) revealed a significantly different results of the ND-R and AASI, which can be expected in approximately 25 % of patients.