Young and middle-aged adults with a systolic BP response to standing greater than 6.5 mm Hg had almost double the risk of major adverse cardiovascular events (MACE) during follow-up compared with other participants.
An exaggerated BP response remained an independent predictor of MACE, even after adjusting for traditional risk factors, including 24-hour BP (hazard ratio [HR], 1.94; 95% CI, 1.10 to 3.44), the study showed.
"The clinical implication is important because now doctors measure blood pressure in young people in the upright posture, but what we say is it must be measured also while standing," said Paolo Palatini, MD, a professor of internal medicine at the University of Padova, Italy, who led the study.
Previous studies have found that an exaggerated BP response to standing is a predictor of future hypertension, CV events, and mortality particularly in older patients, but few prognostic data exist in those who are young to middle age, he noted.
The study, published today in Hypertension, included 1207 participants ages 18 to 45 years with untreated stage 1 hypertension (systolic BP 140 to 159 mm Hg or diastolic BP 90 to 100 mm Hg) in the prospective multicenter HARVEST study that began in Italy in 1990. The average age at enrollment was 33 years.
BP was measured at two visits 2 weeks apart, with each visit including three supine measurements taken after the patient had lain down for a minimum of 5 minutes, followed by three standing measurements taken 1 minute apart.
Based on the average of standing-lying BP differences during the two visits, participants were then classified as having a normal or exaggerated (top decile, lower limit > 6.5 mm Hg) systolic BP response to standing.
The 120 participants classified as "hyperreactors" averaged an 11.4 mm Hg systolic BP increase upon standing, whereas the rest of the participants averaged a 3.8 mm Hg fall in systolic BP upon standing.
At their initial visit, hyperreactors were more likely to be smokers (32.1% vs 19.9%) and coffee drinkers (81.7% vs 73%) and to have ambulatory hypertension (90.8% vs 76.4%).
They were, however, no more likely to have a family history of cardiovascular events and had a lower supine systolic BP (140.5 mm Hg vs 146.0 mm Hg), lower total cholesterol (4.93 mmol/L vs 5.13 mmol/L), and higher HDL cholesterol (1.42 mmol/L vs 1.35 mmol/L).
Age, sex, and body mass index were similar between the two groups, as was BP variability, nocturnal BP dip, and the frequency of extreme dippers. Participants with a normal systolic BP response were more likely to be treated for hypertension during follow-up (81.7% vs 69.7%; P = .003).
In 630 participants who had catecholamines measured from 24-hour urine samples, the epinephrine/creatinine ratio was higher in hyperreactors than normal responders (118.4 nmol/mol vs 77.0 nmol/mol; P = .005).
During a median follow-up of 17.3 years, there were 105 major cardiovascular events, broadly defined to include acute coronary syndromes (48), any stroke (13), heart failure requiring hospitalization (3), aortic aneurysms (3), peripheral vascular disease (6), chronic kidney disease (12), and permanent atrial fibrillation (20).
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