Out-of-Clinic Sympathetic Activity Is Increased in Patients With Masked Uncontrolled Hypertension
Mohammed Siddiqui, Eric K. Judd, Byron C. Jaeger, Hemal Bhatt, Tanja Dudenbostel, Bin Zhang, Lloyd J. Edwards, Suzanne Oparil, David A. Calhoun
Mohammed Siddiqui (USA)
1) Summarise your work in one sentence.
We prospectively analysed clinic and out-of-clinic sympathetic activity in masked uncontrolled hypertensive (MUCH) patients receiving antihypertensive medication(s) compared with true controlled hypertensive patients.
2) Summarise your findings in one sentence.
Patients with MUCH have evidence of heightened out-of-clinic sympathetic activity compared with true controlled hypertensive patients suggesting that heightened out-of-clinic sympathetic activity contributes to the development of MUCH
3) Which were the more important methods you used in this work? If it is not a traditional method, you can briefly explain the concept of that methodology.
This is the first study to evaluate the mechanism of MUCH while study participants were out-of-clinic, when BP levels are by definition higher, consistent with the MUCH phenotype. The study was designed to compare both in-clinic and out-of-clinic sympathetic activity in patients with MUCH versus a comparator group of patients with true controlled hypertension.
In-clinic sympathetic tone, as indexed by plasma catecholamine and metanephrine levels and spot urinary metanephrine levels, were similar in the two study groups. In contrast, out-of-clinic sympathetic tone as indexed by 24-hour urinary catecholamine and metanephrine levels were significantly higher in the MUCH patients compared to the comparator patients with true controlled hypertension.
Similarly, MUCH patients had higher out-of-clinic sympathetic tone as was evidenced by higher BP variability and lower heart rate variability, compared to patients with true controlled hypertension. Differences in out-of-clinic sympathetic tone persisted after multiple linear regression adjustment for diabetes, BMI, smoking and use of sympatholytic medications.
4) What did you learn from this paper, what was your take-home message?
These findings provide evidence of increased out-of-clinic sympathetic output as an important cause of MUCH. If confirmed, our findings suggest that treatment of masked hypertension may preferentially benefit from medications or interventional procedures that effectively target sympathetic output.