1. Review 19
Is there a strong rationale for deferring elective surgery in
patients with poorly controlled hypertension?
Barbara Casadei and Hala Abuzeid
Hypertension remains one of the most common avoidable
medical indications for deferring elective surgery, thereby
increasing both the financial and emotional burden of
having an operation. Although the evidence supporting the
current guidelines on management of hypertension is
among the best available in any field of medicine, our
knowledge on whether high blood pressure (BP) is an
independent perioperative risk factor is plagued by much
uncertainty. Indeed, it is still unclear whether postponing
surgery on the ground of elevated preoperative BP
measurements will lead to a reduction in perioperative
cardiac risk. Similarly, the importance of multiple versus
isolated BP measurements in predicting perioperative
complications has not yet been assessed. As most studies
have evaluated the predictive value of diastolic BP, the risk
of perioperative cardiovascular events associated with
isolated systolic hypertension remains uncertain. With no
controlled evidence to address these issues, no firm
recommendations can be made to improve patients’ safety.
These important issues now need to be addressed by
modern clinical trials. J Hypertens 23:19–22 & 2005
Lippincott Williams & Wilkins.
Journal of Hypertension 2005, 23:19–22
University Department of Cardiovascular Medicine, John Radcliffe Hospital,
Oxford, UK.
Sponsorship:We are grateful for the generous support of the British Heart
Foundation.
Correspondence and requests for reprints to Dr Barbara Casadei, University
Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford OX3
9DU, UK.
Tel: +44 1865 220132; fax: +44 1865 768844;
e-mail: barbara.casadei@cardiov.ox.ac.uk
Received 12 July 2004 Revised 12 August 2004
Accepted 18 August 2004
Introduction
Arterial hypertension is undoubtedly one of the most
important risk factors for cerebrovascular and coronary
heart disease (CHD). Robust epidemiological evidence
indicates that there is a log-linear relationship between
arterial blood pressure (BP) and incidence of stroke and
CHD across a wide range of BPs [1], and a number of
large controlled clinical trials have demonstrated that
lowering BP with antihypertensive medications de-creases
cardiovascular morbidity and mortality [2].
Does this evidence have a bearing in the
perioperative risk assessment of surgical
patients?
This question is of great importance since cardiac
events, such as myocardial infarction or cardiac death,
are relatively frequent perioperative complications, oc-curring
in 1–5% of unselected patients undergoing
non-cardiac surgery [3,4]. Similarly, hypertension is a
common finding in the middle-aged/elderly population
presenting for major non-cardiac surgery, and the rate
of control, particularly of systolic BP, remains poor in
spite of ‘best’ available treatment strategies [5–7].
Anaesthetists are therefore often faced with patients
with poorly controlled hypertension and with the
unresolved question as to whether they should proceed
with anaesthesia, or delay surgery until additional BP-lowering
treatment is instituted. As the evidence for
either course of action is limited, it is not surprising to
observe wide variation in practice [8]. However, the
important fact is that hypertension remains the most
common avoidable medical indication for deferring
elective surgery [9,10].
Admission BP versus BP-related target organ
damage
While the evidence supporting the current guidelines
on management of hypertension [11,12] is amongst the
best available in any field of medicine, our knowledge
of hypertension as a perioperative risk factor is largely
based on small, mostly single-centre, observational
studies.
Classic investigations in the early 1970s showed a
higher incidence of intraoperative arrhythmias and
cardiovascular ischaemia in patients with severely ele-vated
diastolic BP (. 120 mmHg) [13], providing the
first rationale for deferring elective surgery on the basis
of preoperative BP measurements alone. These studies
also highlighted the risk associated with enhanced
reflex sympathetic and BP surges in hypertensive pa-tients
in response to noxious stimuli, such as tracheal
intubation [14,15], and pioneered the perioperative use
of beta-blockers. Later studies showed that uncon-trolled
(mostly systolic) hypertension was associated
with a greater incidence of pre- and postoperative
myocardial ischaemia in patients presenting for elective
non-cardiac surgery [16,17], supporting the notion that
severe hypertension may pose an immediate risk to
surgical patients. From these data it was inferred that
0263-6352 & 2005 Lippincott Williams & Wilkins
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2. 20 Journal of Hypertension 2005, Vol 23 No 1
deferring surgery in order to lower BP, even in the
short term, may lead to a reduction in perioperative
cardiovascular complications. More recently, investiga-tions
have indicated that a history of hypertension is a
predictor of perioperative cardiac death in elective
cardiac and non-cardiac surgery [18,19]. Interestingly,
however, these studies have not been able to demon-strate
a direct relationship between high BP measure-ments
taken at the time of hospital admission and
perioperative cardiac complications [20,21] (Fig. 1),
suggesting that target organ damage associated with
long-standing hypertension may have a stronger prog-nostic
predictive value than the BP level per se [22]. A
similar conclusion can be derived from an earlier study
by Goldman and Caldera [23], who showed that most
of the perioperative complication in patients with a
previous diagnosis of hypertension occurred in the
treated/controlled group, casting some doubt on the
prognostic significance of admission BP measurements,
as these are unlikely to reflect the patient’s ‘usual’ BP.
As there is now compelling evidence indicating that
multiple BP readings by means of ambulatory or home
BP monitoring are better predictors of cardiovascular
events than isolated ‘office’ BP measurements [24–30]
(Fig. 2), it would be important to evaluate whether the
BP burden assessed using these techniques will prove
to be a more accurate predictor of cardiovascular
complications in surgical patients.
Although the potential predictive value of ‘white-coat’
hypertension in surgical patients has never been investi-gated,
%!!

3. %!!

4. Incidence of cardiovascular events according to office and 24-h
systolic blood pressure (BP). In each range of office systolic BP, a 24-h
ambulatory systolic BP 135 mmHg predicted a higher incidence of
cardiovascular events than a 24-h ambulatory systolic blood pressure
, 135 mmHg (from ref. 29, with permission).
the aforementioned absence of a relationship
Fig. 2

5. !

6. !
!
#$ %!
between elevated admission BP and cardiac complica-tions
[20,21], would support the idea that these patients
may have a significantly lower surgical risk than ‘true’
hypertensive subjects, reflecting their lower ‘usual’ BP
and hypertension-related target organ damage. How-ever,
it could equally be reasoned that these subjects’
hyper-reactivity to stress and reduced ability to control
surges in sympathetic activity may be particularly hazar-dous
in the context of anaesthesia and surgery [31].
Systolic or diastolic BP?
If hypertension-related target organ damage (rather
than the BP level at the time of hospital admission)
were a better predictor of perioperative complications,
we may expect different types of hypertension to have
a different impact on the perioperative risk of surgical
patients. For instance, there are epidemiological data
indicating that systolic BP is a more accurate predictor
of cardiovascular events than diastolic BP, particularly
in older subjects [32,33]. Isolated systolic hypertension
and high pulse pressure are well-established markers of
stiffness of the large arterial vessels and important
determinants of left ventricular afterload [34]. Recent
controlled trials have confirmed that antihypertensive
treatment in these patients is highly effective in redu-cing
the risk of stroke, dementia and heart failure [35–
40]; however, the percentage of patients achieving a
‘normal’ systolic BP in response to treatment is rela-tively
low (c. 40–50% versus . 90% control rate for
diastolic BP [6,7,41]). Thus, risk stratification of pa-tients
on the basis of diastolic BP values alone in earlier
250
200
150
100
50
Cases:
systolic
pressure
Controls:
systolic
pressure
Cases:
diastolic
pressure
Controls:
diastolic
pressure
Fig. 1
Arterial pressure (mmHg)
Admission systolic and diastolic pressures of patients who died of a
cardiovascular cause within 30 days of anaesthesia and surgery
(Cases) and matched patients who did not die of a cardiovascular
cause in the perioperative period (Controls). The boxes indicate the
median values and 25th and 75th centiles. There were no significant
differences between admission blood pressure in the two groups (from
ref. 20, with permission).
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7. Deferring elective surgery in hypertensive patients Casadei and Abuzeid 21
studies might have been potentially misleading, parti-cularly
in older patients where isolated systolic hyper-tension
is common. Indeed, in a recent study, systolic
hypertension (. 180 mmHg) alone was found to be a
strong predictor of adverse cerebral outcome and
cardiovascular complications in patients undergoing
coronary bypass surgery [42].
Guidelines
Several guidelines suggest that anaesthesia and surgery
should be deferred in patients with moderate to severe
hypertension (diastolic BP . 110 mmHg) to allow BP
to be treated. Is this course of action associated with a
reduced number of perioperative cardiac complications?
There is surprising little evidence to support this well-accepted
practice. Randomized, placebo-controlled
studies have shown that perioperative treatment with
beta-adrenergic receptor blockers is associated with a
reduction in the incidence of cardiac death or myocar-dial
infarction in high-risk patients undergoing major
non-cardiac [43] or vascular surgery [44]. Although
hypertension was common in this cohort (present in
c. 70% of patients in the study carried out by Mangano
et al. [43]); the possibility that a reduction in BP might
have accounted for at least part of the favourable effect
of beta-adrenoceptor blockade on outcome was not
taken into account, and the protective effect of beta-blockers
was attributed to their preventive effect on
perioperative ischaemia. Nevertheless, perioperative
silent ischaemia has been shown to be more common
in patients with a diagnosis of hypertension, and Stone
et al. [45] demonstrated a significant reduction in
the incidence of postoperative myocardial infarction
in uncontrolled hypertensive subjects (160–200/90–
100 mmHg) treated with beta-blockers. These findings
therefore do not exclude that part of the beneficial
effect of beta-blockers in patients at high risk of
perioperative cardiovascular complications may result
from their BP-lowering effect.
Should all patients with a diagnosis of hypertension
who need major elective surgery be treated with beta-blockers?
Mangano et al. [43] considered beta-blocker
treatment for all patients who met at least two of the
following criteria: older than 65 years, hypertensive,
current smoker, cholesterol . 6 mmol/l or diabetes; that
is, in patients with a 10-year predicted risk of CHD
greater than 15%. Although in-hospital mortality was
similar (3%) in both groups, a 67% reduction in cardiac
events and a 50% reduction in all-cause mortality
become apparent in patients treated with beta-blockers
at 1 year and 2 years of follow-up, respectively.
It is significant that, of all the parameters that have
been tested as predictors of cardiac morbidity in
surgical patients, the most robust are a recent myocar-dial
infarction, a history of cerebrovascular disease and
a diagnosis of heart failure [22]. This suggests that the
main determinant of poor outcome in the perioperative
period is the a priori probability of that outcome. If this
were the case, one could argue that lowering BP shortly
before surgery may not be sufficient to yield a lower
perioperative risk, unless BP were high enough to
constitute an immediate risk to the patient, indepen-dent
of surgery. Furthermore, it is not clear whether
some antihypertensive agents or preparations (e.g. oral
beta-adrenoceptor blockers) would be more effective
than others (e.g. diuretics or calcium antagonists or i.v.
administration of short-acting agents) in preventing
cardiovascular events in the perioperative period.
Summary
The management of hypertension in surgical patients is
a surprisingly dark corner in a field that is illuminated
by some of the strongest and most compelling evidence
available in clinical practice. To date it remains unclear
whether the BP level or BP-related target organ
damage at the time of surgery predicts perioperative
cardiovascular complications in patients undergoing
major surgery, and thus whether deferring surgery in
order to improve BP control will lead to a reduction in
perioperative cardiac risk. Obtaining a reliable assess-ment
of the patients BP by using 24-h home BP
monitoring may help in establishing the importance of
‘usual’ BP as a surgical risk factor. Although the use of
beta-blockers preoperatively has been associated with a
reduced risk of cardiac death, it is unclear whether the
reduction in BP elicited by these agents might have
played a significant part in this outcome.
Thus, in the absence of controlled evidence, no firm
recommendations can be made to improve patients’
safety and reduce the financial burden of postponing
surgery on the grounds of elevated preoperative BP
measurements. As suggested by Fleisher [46] in a
recent editorial, the practice of postponing surgery for
6–8 weeks in patients with a diastolic BP . 110 mmHg
‘must be balanced against the urgency of the surgery
and the acknowledgement of lack of data to determine
if such practices will improve outcome’. These impor-tant
issues now need to be addressed by modern
clinical trials.
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