OS 07-02 DIFFERENCES IN CIRCADIAN BLOOD PRESSURE VARIABILITY PATTERNS BETWEEN JAPANESE AND AMERICAN TREATMENT-RESISTANT HYPERTENSIVE POPULATIONS.

OBJECTIVE: Dynamic changes in 24-hour ambulatory blood pressure (BP) are associated with basal autonomic function and cardiovascular risk. We examined the influence of ethnicity on these parameters by comparing ambulatory BP dynamics in Japanese, African American (AA), and white populations with treatment-resistant hypertension.

DESIGN AND METHOD: Both HTN-Japan (N = 41) and SYMPLICITY HTN-3 (N = 384 white and 140 AA) enrolled patients with office systolic BP ≥ 160 mmHg and 24-hour ambulatory systolic BP ≥ 135 mmHg while on ≥3 antihypertensive medications. Indices of circadian variation in ambulatory BP, including morning dynamic surge and maximum dynamic surge, were retrospectively compared after adjusting for differences in baseline demographics.

RESULTS: The Japanese and white cohorts were of similar age (58 ± 12 vs 59 ± 11 years) but AA patients were younger (53 ± 10 years, p = 0.016 vs Japanese). All 3 cohorts had similar baseline office systolic BP (180 mmHg in Japanese vs 182 mmHg in AA vs 179 mmHg in white patients, 3-way p = 0.32), but 24-hour ambulatory BP was highest in the Japanese patients (164 mmHg vs 161 mmHg in AA vs 158 mmHg in white patients, 3-way p = 0.014). The Japanese cohort had significantly (p < 0.05) lower body mass index, less obstructive sleep apnea, and less hypercholesterolemia than AA or white patients. Baseline stroke was greatest in the Japanese (17%) compared with AA (15%) or white patients (7%), 3-way p = 0.009. The Japanese cohort had significantly greater average morning, maximum morning, and maximum nighttime systolic BP. Morning dynamic surge parameters were also greater in the Japanese patient population (Figure). These differences persisted after multivariate analysis adjusting for baseline characteristics.

CONCLUSIONS: Greater circadian variability, including dynamic surge parameters, in Japanese as compared with AA and white patients may indicate differences in the underlying autonomic mechanism of resistant hypertension in these populations. Differences in autonomic function may lead to more specific drug- and device-based therapy strategies based on ethnicity.