Background: It is difficult to draw definite conclusions about the prevalence and clinical characteristics of patients with resistant hypertension because of the heterogeneity of study designs described in published studies.
Objectives: To estimate the prevalence of resistant hypertension, the associated cardiovascular risk factors and the degree of target-organ damage, and to analyze the differences between true resistant hypertension (TRH) and white-coat resistant hypertension (WCRH).
Design: Cross-sectional study.
Methods: Patients who visited the Hypertension Clinic with resistant hypertension were sequentially included. Resistant hypertension was defined as an average of three measurements of systolic blood pressure, >/= 160 mmHg or a diastolic blood pressure >/= 95 mmHg, or both, in patients treated with a triple-drug regimen, over at least 2 months. Twenty-four-hour ambulatory blood pressure monitoring and M-mode bi-dimensional echocardiography were performed. WCRH was defined as a mean daytime ambulatory blood pressure </= 135/85 mmHg; patients with higher values were classified as having TRH.
Results: Of 1200 hypertensive subjects who visited the clinic, 60 patients with resistant hypertension were included [mean age 59+/-8 years; 38 women (63%)]. Office blood pressure was 173+/-14/100+/- 8 mmHg. Of 36 patients with a good quality echocardiograph, 18 had left ventricular hypertrophy. Twenty cardiovascular events were recorded in 16 patients. Obesity was present in 43% of patients, diabetes in 28%, and hypercholesterolemia in 47%. Hypoalphalipoproteinemia was detected in 18%of the patients, all of whom had TRH (P = 0.01). Nineteen subjects (32%) had WCRH. The subjects with TRH had a higher office systolic blood pressure, greater frequency of hypoalphalipoproteinemia than those who had WCRH and a greater proportion of clinical target-organ damage.
Conclusions: Resistant hypertension is uncommon in clinical practice. Resistant hypertension is associated with multiple cardiovascular risk factors, including left ventricular hypertrophy. A third of patients with resistant hypertension achieve adequate control of their blood pressure outside the physician's office. The proportion of patients with clinical target-organ damage is greater in subjects with TRH than in those with WCRH.