Assessment of target organ damage in patients with resistant hypertension

Background: Resistant hypertension (RH) is defined by most guidelines as blood pressure that remains above goal despite use of at least 3 antihypertensive agents of different classes, including a diuretic, prescribed at optimal doses. Few data are available on the clinical characteristics and on the prevalence of different forms of organ damage in these patients. Aim of the study was to evaluate the prevalence of RH and the presence of associated cardiovascular (CV) risk factors and target organ damage (TOD) in a group of hypertensive patients selected from a general population sample in Northern Italy (Vobarno Study). Methods: 478 subjects (mean age 58±3 yrs, 44% males, 66% hypertensives) underwent laboratory examinations and both clinic and 24 hours BP measurement (Spacelabs 90207). Left ventricular (LV) and carotid artery structure were assessed by ultrasound and carotid-femoral PWV was measured using Complior SP (Artech, Pantin, France). Results: Among treated hypertensive patients 9.5% were defined as resistant. Patients with RH were older (mean age 69±4 vs 60±9 yrs, p<0.01), had higher glucose values (115±47 vs 103±24 mg/dl, p<0.05) and were more often of female gender (female 73% vs male 27%, p<0.05); no difference in BMI and lipid levels was observed. Estimated glomerular filtration rate (MDRD) was lower in RH (72±17 mL/min/1,73 m2 vs 82±16, p<0.01). Patients with RH had greater LV mass index (47.7±10.5 vs 40.7±10.0 gr/m2.7, p<0.001), LV relative wall thickness (0.42±0.08 vs 0.38±0.05 p<0.001), intima media thickness (Meanmax 1.47±0.42 vs 1.18±0.30 mm, p=0.01) and PWV (13.3±2.8 vs 11.8±2.8 m/sec, p<0.05). Conclusions: In a group of hypertensive patients selected from a general population in Northern Italy the prevalence of RH was relatively high. Patients with RH were older, had higher glucose values and a higher prevalence of cardiac, vascular and renal organ damage.