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Out-of-Clinic Sympathetic Activity Is Increased in Patients With Masked Uncontrolled Hypertension
Mohammed Siddiqui1, Eric K Judd2, Byron C Jaeger3
1From the Vascular Biology and Hypertension Program, Division of Cardiovascular Disease (M.S., T.D., S.O., D.A.C.), University of Alabama at Birmingham.
Insights
Masked uncontrolled hypertension (MUCH) involves controlled clinic blood pressure (BP) but high out-of-clinic BP. MUCH patients show increased sympathetic activity outside the clinic compared to truly controlled hypertensive individuals.
Area of Science:
- Cardiovascular Medicine
- Hypertension Research
- Autonomic Nervous System
Background:
- Masked uncontrolled hypertension (MUCH) is characterized by normal in-clinic blood pressure (BP) readings but elevated out-of-clinic BP.
- Understanding the physiological mechanisms underlying MUCH is crucial for effective hypertension management.
- Previous research suggests potential differences in sympathetic nervous system activity between MUCH and true controlled hypertension.
Purpose of the Study:
- To investigate whether patients with masked uncontrolled hypertension exhibit greater out-of-clinic sympathetic activity compared to true controlled hypertensives.
- To compare in-clinic and out-of-clinic sympathetic markers in patients with MUCH and true controlled hypertension.
Main Methods:
- Prospective recruitment of 237 hypertensive patients on medication.
- Evaluation included in-clinic automated office BP, plasma catecholamines, spot-urine/plasma metanephrines, 24-hour ambulatory BP monitoring (ABPM), and 24-hour urinary catecholamines/metanephrines.
- Analysis of 72 true controlled hypertensives and 80 MUCH patients based on BP control in-clinic and out-of-clinic.
Main Results:
- MUCH patients demonstrated significantly higher out-of-clinic BP variability and lower heart rate variability compared to true controlled hypertensives.
- Elevated out-of-clinic urinary catecholamines and metanephrines were observed in MUCH patients, indicating heightened sympathetic activity.
- No significant differences in in-clinic plasma catecholamines or spot-urine/plasma metanephrines were found between the groups.
Conclusions:
- Masked uncontrolled hypertension is associated with heightened sympathetic nervous system activity specifically during out-of-clinic conditions.
- These findings suggest that increased out-of-clinic sympathetic drive may play a role in the pathophysiology of MUCH.
- Further research is warranted to explore the clinical implications and therapeutic strategies for managing MUCH.
Abstract:
Masked uncontrolled hypertension (MUCH) is defined as controlled automated office blood pressure (BP; AOBP <135/85 mm Hg) in-clinic in patients receiving antihypertensive medication(s) but uncontrolled BP out-of-clinic by 24-hour ambulatory BP monitoring (ABPM; awake ≥135/85 mm Hg). We hypothesized that MUCH patients have greater out-of-clinic sympathetic activity compared with true controlled hypertensives. Patients being treated for hypertension were prospectively recruited after 3 or more consecutive clinic visits. All patients were evaluated by in-clinic automated office BP, plasma catecholamines, and spot-urine/plasma metanephrines. In addition, out-of-clinic 24-hour ABPM, 24-hour urinary for catecholamines and metanephrines was done. Out of 237 patients recruited, 169 patients had controlled in-clinic BP of which 156 patients had completed ABPM. Seventy-four were true controlled hypertensives, that is controlled by clinic automated office BP and by out-of-clinic ABPM. The remaining 82 were controlled by clinic automated office BP, but uncontrolled during out-of-clinic ABPM, indicative of MUCH. After exclusion of 4 patients because of inadequate or lack of 24-hour urinary collections, 72 true controlled hypertensive and 80 MUCH patients were analyzed. MUCH patients had significantly higher out-of-clinic BP variability and lower heart rate variability compared with true controlled hypertensives, as well as higher levels of out-of-clinic urinary catecholamines and metanephrines levels consistent with higher out-of-clinic sympathetic activity. In contrast, there was no difference in in-clinic plasma catecholamines and spot-urine/plasma levels of metanephrines between the 2 groups, consistent with similar levels of sympathetic activity while in clinic. MUCH patients have evidence of heightened out-of-clinic sympathetic activity compared with true controlled hypertensives, which may contribute to the development of MUCH.
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