Background and aim: Clinical characteristics of resistant hypertensive patients in comparison to controlled patients have not been fully investigated in large cohorts. The aim of the study was to evaluate clinical differences, target organ damage and ambulatory blood pressure monitoring in resistant hypertensive patients and patients controlled on three or less drugs.
Methods: In December 2010, from the Spanish Ambulatory Blood Pressure Monitoring Registry, we identified 14 461 patients fulfilling criteria of resistant hypertension and 13 436 hypertensive patients controlled on three or less drugs. Clinical characteristics were compared between these two groups.
Results: Compared to controlled patients, those having resistant hypertension were older, more obese and had longer hypertension duration. They also had more frequently diabetes, dyslipidemia, reduced renal function, microalbuminuria, left-ventricular hypertrophy and previous history of cardiovascular events. In multivariate analyses, hypertension duration, obesity, abdominal obesity, left-ventricular hypertrophy, reduced estimated glomerular filtration rate, and microalbuminuria were independently associated with resistant hypertension. Resistant hypertensive patients had higher ambulatory blood pressures, but differences between office and ambulatory blood pressure (white-coat effect) were also more pronounced in this group, revealing a proportion of 40% of patients with normal 24-h blood pressure. On the contrary, values of 24-h blood pressure above 130 and/or 80 mmHg (masked hypertension) were present in 31% of apparently controlled patients.
Conclusion: Resistant hypertension is associated with obesity, longer hypertension duration and kidney and cardiac damage. Ambulatory blood pressure monitoring reveals that white-coat hypertension is common among resistant hypertensive patients, as well as is masked hypertension among apparently controlled patients.