Central BP thresholds proposed
medwireNews: Central blood pressure (CBP) edges closer to clinical use with the establishment of a threshold predictive for cardiovascular mortality.
The results of an observational study of more than 3000 Taiwanese people indicate that 130/90 mmHg may be the optimal CBP cutoff for hypertension, with normotension at pressures below 110/80 mmHg.
“Physiologically, with its close proximity to vital organs and the better prognostic value, CBP should be the most relevant BP relating to vascular events,” say lead researcher Chen-Huan Chen (Taipei Veterans General Hospital, Taiwan) and team in the Journal of the American College of Cardiology.
“Cuff BP is not so much a surrogate, but a compromised measure that is recorded because of technical limitations.”
The derivation cohort comprised 1272 people, aged an average of 52 years, who were free of overt cardiovascular disease. Their average cuff systolic BP was 11.6 mmHg higher than their average CBP, which was measured by a validated noninvasive method.
The researchers obtained their proposed CBP thresholds from the derivation cohort by calculating the CBP equivalents to standard cuff BP thresholds and examining their association with cardiovascular mortality over a median 15 years of follow up.
In a validation cohort of 2501 people, aged an average of 54 years and with a median 10 years of follow up, prehypertension (systolic CBP 110–129 mmHg) was associated with a nonsignificantly increased risk for cardiovascular mortality, relative to normotension (systolic CBP <110 mmHg). And hypertension (≥130 mmHg) was associated with significant risk increases of 2.14-fold for total mortality, 3.08-fold for cardiovascular mortality, and 6.12-fold for stroke mortality.
Each 10 mmHg increase in systolic CBP significantly raised the risk for all these outcomes, whereas cuff systolic BP was only associated with total and stroke mortality.
In an editorial accompanying the study, Michael Weber (State University of New York, USA) and Raymond Townsend (University of Pennsylvania, Philadelphia, USA) note that the exclusion of patients with overt cardiovascular disease “is acceptable in describing the natural history of BP values but not necessarily relevant to patients in clinical practice.”
They also observe that risk thresholds for nonfatal vascular events could be different, and stress that only intervention trials can prove the benefits of treating to any CBP target.
“Even so,” they say, “we believe we are now at a point where central BP should emerge not only as a key endpoint in research studies but as a measurement of growing interest and value to clinicians.”
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter