Blood Pressure Hyperreactivity to Standing: a Predictor of Adverse Outcome in Young Hypertensive Patients

Abstract

The prognostic significance and the mechanisms of blood pressure (BP) hyperreactivity to standing remain controversial. This study aims to evaluate the association of orthostatic hyperreactivity with major adverse cardiovascular and renal events in a cohort of young hypertensive subjects. We studied 1207 untreated subjects screened for stage I hypertension with a mean age of 33.1±8.6 years. The orthostatic BP change was calculated as the difference between 6 standing and 6 supine BP readings obtained during 2 separate visits. Hyperreactivity to standing was defined as the standing-supine systolic BP difference in the top decile. The mean difference in the whole group was -2.5±7.3/4.6±5.4 mm Hg. Ambulatory hypertension evaluated with 24-hour recordings was more common in Hyperreactors than Normoreactors (90.8% versus 76.4%, P=0.001). In 630 participants in whom 24-hour urinary catecholamines were measured, epinephrine/creatinine ratio was higher in hyperreactors (118.4±185.6 versus 77.0±90.1 nmol/mol, P=0.005). During a 17.2-year follow-up, 105 major adverse cardiovascular and renal events were accrued. In a multivariate Cox model, hyperreactivity to standing was an independent predictor of major adverse cardiovascular and renal events with a hazard ratio of 1.97 (95% CI, 1.10-3.52). Hyperreactivity remained an independent predictor of adverse events even when ambulatory BP data and incident hypertension during follow-up were included in the Cox model (hazard ratio, 1.94 [95% CI, 1.10-3.44]). Our data indicate that in young-to-middle-age hypertensive subjects an exaggerated systolic BP response to standing is associated with sympatho-adrenergic hyperreactivity and is an independent predictor of major adverse cardiovascular and renal events. Orthostatic BP assessment gives the advantage of simple acquisition and provides prognostic information on top of ambulatory BP.

Keywords: blood pressure; cardiovascular diseases; catecholamines; dyslipidemias; hypertension.