Response to Unmasking True Resistant Hypertension: Is the Real-World Resistance Just Revealed?

We thank Thomopoulos and Tsioufis¹ for their interest in our article² and also for their positive feedback and criticism. We will try to answer directly to the 3 points raised in their letter.

First, we would like to clarify our analyses regarding treatment posology. Although, in the protocol of the Spanish Ambulatory Blood Pressure Monitoring Registry, details of treatment posology were collected on a 3-category scheme, results from this cohort of patients with resistant hypertension indicated that only 41 patients (0.5% of the cohort) received part of their antihypertensive treatment at lunchtime, whereas the majority received all of the medication in the morning (6202 patients; 74.8%) or in a morning-evening schedule (2052 patients; 24.7%). Moreover, these 41 patients also received antihypertensive medication in the evening. Because having part of the medication at bedtime has been reported to be associated with a better blood pressure control in hypertensives,³ our analyses were restricted to the comparison of these patients versus those receiving their medication only in the morning, revealing no differences in the prevalence of white-coat–resistant hypertension.²

Second, we agree with Thomopoulos and Tsioufis¹ that sleep apnea syndrome could be an important cause of resistance, and it has been reported recently that continuous positive pressure therapy ameliorates blood pressure in resistant hypertensive patients.⁴ Unfortunately, when the registry was initiated, a systematic collection of data regarding sleep apnea diagnosis and treatment was not planned.

Third, we have performed additional analyses from our registry to provide data about the prevalence of masked resistant hypertension in our cohort. Thus, from the original cohort of 68 045 patients, we identified 2603 subjects who were treated with 3 antihypertensive drugs and had normal values for office blood pressure. Mean±SD values of systolic and diastolic blood pressures were, respectively, 127±11/75±9 mm Hg for office and 122±13/71±9 mm Hg for the 24-hour period pressure. The prevalence of masked hypertension (24-hour values ≥130 and/or 80 mm Hg) was 32% of this cohort, higher than we reported previously in the general cohort of treated patients, independent of the number of drugs used.⁵ These results are in the direction expressed by Thomopoulos and Tsioufis¹ that the prevalence of masked resistant hypertension counterbalances the pseudoresistance observed because of the white-coat phenomenon.

• © 2011 American Heart Association, Inc.