PS-C28-5: ROLE OF SYMPATHETIC NERVOUS SYSTEM IN ATTENDED AND UNATTENDED BP LEVELS IN ESSENTIAL HYPERTENSION

Abstract

Objective: It has been hypothesized that unattended blood pressure (BP) measurement may provide complementary clinical information to conventionally attended BP measurement. The role of sympathetic nervous system activation during attended and unattended BP measurements is largely undetermined. Design and method: We studied 161 untreated hypertensive patients undergoing attended and unattended office BP measurements. Patients were divided into two groups - group A, unattended systolic BP greater than the attended systolic BP (n = 79), and group B, unattended systolic BP equal or lower than the attended (n = 82). All participants underwent muscle sympathetic nerve activity (MSNA) estimation by microneurography. Unattended and attended BP measurements were performed with the same device in a random order for each patient on the day of MSNA recording. MSNA levels were compared between the two groups. Results: We examined 161 hypertensive patients [54% men, mean age 56 ± 12 years, BMI 29 ± 5 kg/m2, mean attended BP 140 ± 17 / 87 ± 13 mmHg, mean unattended BP 141 ± 20 / 85 ± 12 mmHg]. Group A and group B had statistically significant differences between attended systolic BP (136.7 ± 17.8 vs 143.7 ± 15.7 mmHg respectively, p = 0.009), attended diastolic BP (85.5 ± 14.7 vs 89.7 ± 11.4 mmHg respectively, p = 0.004), unattended systolic BP (145.5 ± 19 vs 135.7 ± 19.9 mmHg respectively, p = 0.002) and unattended diastolic BP (86.9 ± 13 vs 83.2 ± 11.2 mmHg respectively, p = 0.05). However, the two groups did not differ as regards MSNA levels (42.5 ± 10 vs. 41.6 ± 7.8 bursts per minute respectively, p = 0.5). MSNA levels did not correlate to attended and unattended systolic/diastolic BP in both groups. Conclusions: In conclusion, sympathetic nervous system activity may not contribute significantly to the differential BP levels during attended or unattended BP measurements.