Abstract 19101: Increased Sympathetic Nervous System Activity in Refractory Hypertensive Patients in Contrast to Controlled and True Resistant Hypertensive Patients
Within the population of patients with resistant hypertension (RHTN), a unique phenotype with unexplained mechanisms of treatment failure has been identified. This phenotype remains uncontrolled despite optimal medical therapy who we refer to as having refractory hypertension (RefHTN) in contrast to true or controlled RHTN. The current study prospectively compared biochemical parameters, indices of arterial compliance, endothelial function and cardiohemodynamics in patients with RefHTN and a matched cohort of controlled and true resistant hypertensive patients. From 2009 to 2012, refractory patients were identified in a referral hypertension clinic using the following criteria: uncontrolled blood pressure (BP) on 5 or more antihypertensive medications (including chlorthalidone and spironolactone) after ≥ 3 visits within a minimum 6-month follow-up period. All 40 patients underwent measurement of 24-hr BP, heart rate (HR); pulse wave analysis (PWA); augmentation index (AIx75); aortic pulse pressure (APP); pulse wave velocity (PWV); arterial flow-mediated dilation (FMD), electrocardiogram, and impedance cardiogram. Baseline characteristics were similar; although, refractory patients were younger and were treated with an average of 7 different antihypertensive classes. ABPM confirmed a difference in systolic (177±29 vs 133±6 mm Hg, p<0.001) and diastolic BP (101±17 vs 79±10 mm Hg, p< 0.001) in the true or controlled vs refractory groups. Average 24-hr HR was higher in patients with RefHTN (78±8 vs 69±7 bpm, p=0.039) despite being on more β-blockers. PWV was greater(12±3 vs 10±3 m/s, p=0.044), as was AIx75 (31±7 vs 17±12 %). Brachial artery FMD was more reduced in patients with RefHTN (6.6 vs 9.4%). Impedance electrocardiogram showed significantly increased systemic vascular resistance(supine 3876.4 vs 1372.9 , p<0.001 and standing 1980.1 vs 1197.7 dyne sec cm-5,p=0.037). Patients with RefHTN have increased arterial stiffness, central blood pressure,systemic vascular resistance, and endothelial dysfunction compared to patients with controlled and true RHTN, consistent with higher sympathetic activity in his group suggesting that increased adrenergic output contributes importantly to antihypertensive treatment failure.
- © 2012 by American Heart Association, Inc.