Abstract P641: Angiotensin Receptor Blocker Improves Pressure Natriuresis in Select African-Americans
Objective: Hypertension in ~30-60% of African-Americans (AAs) is resistant to single or combination therapy, indicating the necessity for novel screening strategies in this population. Our research supports a strategy that identifies a subset of AAs (approximately 1 in 3) who increase their retained sodium load during mental stress (MS) with an accompanying volume-mediated increase in blood pressure (BP) that remains elevated until the volume expansion diminishes. We hypothesize is due to activation of the renin-angiotensin system (RAS).
Design and Method: We conducted a double blind placebo controlled crossover trial comparing the effects of irbesartan to placebo on sodium handling and consequent BP during MS. Subjects included 213 AA adults, of which 168 (78%) completed the study. After 7 days of vehicle (placebo or irbesartan) subjects underwent a 3 hr protocol comprised of 1 hr rest, 1 hr competitive video games, and 1 hr recovery. Blood and urine were obtained after each hour and BP every 15 mins. A 1 week washout ensued before subjects crossed over to repeat with the alternate vehicle. Subjects were divided into those who exhibited expected increases in urinary sodium excretion (UNaV) (Excreters) or reduced UNaV (Retainers) during MS as defined by previous data. Statistical analysis was performed using crossover methods with a pooled analysis that assumes equal variances and the Satterthwaite test of treatment difference (Stest) that assumes unequal variances.
Results: Both statistical tests revealed that UNaV increased significantly for retainers (n=55) on irbesartan (p<0.002 and p<0.015, mean ± SD (pooled =7.15 ± 6.78, Stest =7.15)) normalizing the sodium response to MS. Irbesartan also enhanced UNaV during MS in excreters (n=113) with significant differences (p<0.001 and p<0.001, mean ± SD (pooled = 4.18 ± 9.03, Stest =4.18)). Overall SBP response was significantly reduced with treatment (p< 0.001 and p< 0.001, mean ± SD (pooled = -5.08 ± 3.19, Stest = -5.08)).
Conclusion: Agents that block the RAS are not usually considered effective in AAs. However, our results suggest identification and treatment of AAs who increase their retained sodium load during MS with these agents will reduce the percentage of AAs with hypertension resistant to standard therapy.
Author Disclosures: G.A. Harshfield: None. C. Hanevold: None. D. Stewart: None. Y. Dong: None. S. Mathur: None.
- © 2015 by American Heart Association, Inc.