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Central blood pressure: current evidence
and clinical importance
Carmel M. McEniery1*, John R. Cockcroft2, Mary J. Roman3,
Stanley S. Franklin4, and Ian B.Wilkinson1
1Clinical
Pharmacology Unit, University of Cambridge, Addenbrooke’s
Hospital, Box 110, Cambridge CB22QQ, UK; 2Department of Cardiology,Wales Heart Research Institute,
Cardiff
CF14 4XN, UK; 3Division
of Cardiology,Weill Cornell Medical College, New York, NY 10021, USA; and 4University of California, UCI School of
Medicine, Irvine, CA 92697-4101, USA
Received 29 April 2013;
revised 27 November 2013; accepted 17 December 2013; online
publish-ahead-of-print 23 January 2014
and central pressure. Therefore, basing treatment decisions on central,
rather than brachial pressure, is likely to have important implications
for the future diagnosis and management of hypertension. Such a paradigm
shift will, however, require further, direct evidence that selectively
targeting central pressure, brings added benefit, over and above that
already provided by brachial artery pressure.
Central pressure † Blood pressure † Anti-hypertensive treatment † Cardiovascular risk
Introduction
The brachial cuff sphygmomanometer was introduced into medical
practice well over 100 years ago, enabling the routine, non-invasive,
measurement of arterial blood pressure. Life insurance companies
were among the first to capitalize on the information provided by
cuff sphygmomanometry, by observing that blood pressure in
largely asymptomatic individuals relates to future cardiovascular
risk?observations that are nowsupported by a wealth of
epidemiological
data.1 The most recent Global Burden
of Disease report2
identified hypertension as the leading cause of death and disability
worldwide. Moreover, data from over 50 years of randomized controlled
trials clearly demonstrate that lowering brachial pressure,
in hypertensive individuals, substantially reduces cardiovascular
events.1,3 For these reasons, measurement of brachial blood pressure
has become embedded in routine clinical assessment throughout the
developed world, and is one of the most widely accepted ‘surrogate
measures’ for regulatory bodies.
The major driving force for the continued use of brachial blood
pressure has been its ease of measurement, and the wide variety of
devices available for clinical use. However, we have known for over
half a century that brachial pressure is a poor surrogate for aortic
pressure, which is invariably lower than corresponding brachial
values. Recent evidence suggests that central pressure is also more
strongly related to future cardiovascular events4 ? 7 than brachial
pressure, and responds differently to certain drugs.8,9 Appreciating
this provides an ideal framework for understanding the much publicized
inferiority of atenolol and some other beta-blockers,10 compared
with other drug classes, in the management of essential
hypertension. Although central pressure can now be assessed noninvasively
with the same ease as brachial pressure, clinicians are unlikely
to discard the brachial cuff sphygmomanometer without
robust evidence that cardiovascular risk stratification, and monitoring
response to therapy, are better when based on central rather
than peripheral pressure. Central pressure assessment and accuracy
will also have to be standardized, as it has been for brachial pressure
assessment with oscillometric devices. This review will discuss our
current understanding about central pressure and the evidence
required to bring blood pressure measurement, and cardiovascular
risk assessment into the modern era.
Physiological concepts
Arterial pressure varies continuously over the cardiac cycle, but in
clinical practice only systolic and diastolic pressures are routinely
reported. These are invariably measured in the brachial artery
using cuff sphygmomanometry?a practice that has changed
little
over the last century. However, the shape of the pressure waveform
* Corresponding
author. Tel: +44 1223 336806, Fax: +44 1223 216893, Email: cmm41@cam.ac.uk
Published on behalf of the European Society of Cardiology. All rights
reserved. &The Author 2014. For
permissions please email: journals.permissions@oup.com
European Heart Journal (2014) 35, 1719?1725 doi:10.1093/eurheartj/eht565
Pressure measured with a cuff and sphygmomanometer in the brachial artery
is accepted as an important predictor of future cardiovascular risk.However,
systolic pressure varies throughout the arterial tree, such that aortic
(central) systolic pressure is actually lower than corresponding brachial values, although
this difference is highly variable between individuals. Emerging evidence now
suggests that central pressure is better related to
future cardiovascular events than is brachial pressure. Moreover, anti-hypertensive
drugs can exert differential effects on brachial and
central pressure. Therefore, basing treatment decisions on central, rather than
brachial pressure, is likely to have important implications for the future diagnosis and management of hypertension. Such a
paradigm shift will, however, require further, direct evidence that selectively targeting central pressure, brings added benefit, over and above
that already provided by brachial artery pressure.As discussed earlier, a full
synthesis of the available evidence concerning
central pressure and the risk of future cardiovascular events is now required. However, it
will also be necessary to determine the clinical
relevance of differences between brachial and central pressure
for the individual patient, especially given the relatively high
correlation between the two. Emerging data support the prognostic superiority of both 24-h ambulatory blood pressure monitoring
(ABPM)79 ? 81 andhomemonitoring81 in comparison with office measurements. Interestingly, a recent
study82 demonstrated that 24-h ambulatory cuff pressures
were comparable with office central pressure
measurements in the prediction of risk, although the significance of this study awaits
confirmation.83 As yet,
there are no data comparing the predictive value ofhomemonitoring vs. central
pressure in the
prediction of risk. Ultimately, it will be necessary to evaluate the
prognostic value of 24-h ambulatory central pressure.With the recent
development of ambulatory central pressure systems,84,85 this is now
possible and it may be reasonable to hypothesize that 24-h central, rather than brachial ABPM
would be superior in terms of risk prediction.
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