Target-organ damage and cardiovascular risk profile in resistant hypertension. Influence of the white-coat effect.
ABSTRACT 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.
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).
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.
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.
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.