Routine Ambulatory BP Monitoring Benefits

AMBULATORY BP MONITORING-SHOULD IT
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TOPIC OVERVIEW
 INTRODUCTION
 MEASUREMENT OF ABP
 INTERPRETATION OF ABPM
 PROGNOSTIC VALUE OF ABPM
 WHITE COAT HYPERTENSION
 INDICATIONS FOR ABPM
 INFLUENCE ON THERAPY OF HYPERTENSION
 SUMMARY AND RECOMMENDATIONS
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INTRODUCTION
 Ever since arterial blood pressure was first measured
by Stephen Hales’ more than 250 years ago, it has been
understood that such pressure is not static, but a
constantly varying entity.
 At the same time, physicians have always been advised
that the gold standard for blood pressure
determination is a small number of clinical
measurements made at relatively infrequent intervals
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 One of the first studies questioning the validity of
clinic measurement of blood pressure was published
in 1940 by Ayman and Goldshine.
 They instructed 34 of their hypertensive patients to
take their own blood pressures or to have family
members take them at home.
 The patients were followed for an average of 22
months, during which time they averaged 21 visits each
to the authors’ clinic.
 At the end of the study more than 2,800 clinic blood
pressure measurements and more than 40,000 home
measurements had been made and recorded.
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 The authors reported that in every one of the 34 cases
the blood pressure readings taken at home were lower
than those taken in the clinic by the doctor.
 The average home readings were roughly 50 mmHg
systolic and 25 mmHg diastolic less than the average
clinic readings.
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 The development of ABPM originates with the work of
Maurice Sokolow, an internist in San Francisco, who
was impressed by the fact that many hypertensive
patients with very high blood pressures experienced a
normal life expectancy.
 In 1962 he and his colleagues Hinman et al developed
the initial semiautomatic ABPM device.
 It consisted of a blood pressure cuff that was manually
inflated by the subject, and a tape recorder on which
the Korotkoff sounds were recorded.
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MAURICE SOKOLOW
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 Sokolow et al. subsequently published a series of
classic papers establishing the clinical value of ABPM.
 These demonstrated the variability of blood pressure
during the day and its relatively poor correlation with
casual pressures taken in the office.
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 Sokolow et al. were the first to show that ambulatory
pressures correlate more closely than clinical pressures
with damage to heart and arteries caused by
hypertension.
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MEASUREMENT OF ABPM
 ABPM is determined using a device worn by the
patient that takes blood pressure(BP) measurements
over a 24 to 48 hour period, usually every 15 to 20
minutes during the daytime and every 30 to 60
minutes during sleep.
 These blood pressures are recorded on the device, and
the average day (diurnal) or night (nocturnal) blood
pressures are determined from the data by a computer.
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INTERPRETATION OF ABPM
 Unique data provided by ABPM include:
 24-hour average blood pressure (BP)daytime (awake)
BP
 Night time (asleep) BP
 Systolic blood pressure load
 Diastolic blood pressure load
 Nocturnal dipping of the BP
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Definition of hypertension
 24-hour average BP - Normotension is defined as a BP
less than 130/80 mmHg, and hypertension is defined
as a BP greater than or equal to 135/85 mmHg.
 Daytime (awake) BP - Normotension is defined as a BP
less than 135/85 mmHg, and hypertension is defined as
a BP greater than or equal to 140/90mmHg.
 Night time (asleep) BP - Normotension is defined as a
BP less than 120/70 mmHg, and hypertension is
defined as a BP greater than or equal to 125/75 mmHg
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Blood pressure load
 The BP load is defined as the percentage of
ambulatory systolic and diastolic pressures exceeding
140 mmHg and 90 mmHg during the daytime, and 120
mmHg and 80 mmHg during sleep.
 The overall BP load may also be a determinant of
cardiovascular risk.
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 The systolic BP load in normotensive subjects
increases from approximately 9 percent of readings in
young adults to as high as 80 percent in the elderly.
 The diastolic BP load does not appear to vary
significantly with age.
 Studies in untreated hypertensive subjects suggest
that the likelihood of developing cardiac abnormalities
is markedly increased when the daily BP load is 40
percent or more.
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PROGNOSTIC VALUE OF ABPM
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Prediction of cardiovascular risk
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Progression of kidney disease
 A cohort study of 217 patients suggested that elevated
blood pressure by ABPM correlated more strongly with
progression to end-stage renal disease (ESRD) than
clinic systolic blood pressure.
 In addition, night ambulatory blood pressure was a
strong predictor of the composite outcome of death
and ESRD
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Masked hypertension
 As many as 10 to 40 percent of patients who are
normotensive by conventional clinic measurement are
hypertensive by ABPM.
 This phenomenon is called masked hypertension or
isolated ambulatory hypertension.
 It has only been identified by screening clinical
studies, since patients who are normotensive by office
readings do not typically undergo ambulatory
monitoring.
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 Masked hypertension has been associated with an
increased long-term risk of sustained hypertension
and cardiovascular morbidity .
 Because of the risk associated with masked
hypertension, ambulatory blood pressure monitoring
should be considered in patients referred for possible
hypertension.
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Nocturnal blood pressure and
nondippers
 A cohort study of 7458 patients in six countries from
Europe, Asia, and South America found that both
daytime and night time BP predicted all cardiovascular
events.
 Night time blood pressure, adjusted for daytime BP,
predicted total, cardiovascular, and non cardiovascular
mortality.
 In contrast, daytime blood pressure, adjusted for
blood pressure measured during sleep, only predicted
noncardiovascular mortality AMBULATORY BP MONITORING-SHOULD IT
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 The average nocturnal BP is approximately 15 percent
lower than daytime values in both normals and
hypertensive patients.
 Failure of the BP to fall by at least 10 percent during
sleep is called nondipping.
 The underlying mechanisms of nondipping are
unknown, but intrinsic renal defects may contribute.
 There is also some evidence suggesting that melatonin
plays a role.
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 Independent of the degree of hypertension,
nondipping is a risk factor for the development of left
ventricular hypertrophy (LVH), heart failure and other
cardiovascular complications .
 Extreme "dipping" (eg, >20 percent nocturnal decline
in BP) and a large morning increase in BP are also
potentially deleterious .
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 Nondipping has also been associated with
microalbuminuria and faster progression of
nephropathy in patients with diabetes mellitus.
 Nondipping may be a risk factor for decline in
glomerular filtration rate, and ESRD and death among
patients with chronic kidney disease.
 The presence of sleep apnea should also be considered
in nondippers.
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WHITE COAT HYPERTENSION
 ANXIETY- MAIN CAUSE
 The diagnosis of white coat hypertension (also called
isolated clinic or office hypertension) is applied to
patients with office readings that average more
than 140/90 mmHg and reliable out-of-office readings
that average less than 140/90 mmHg.
 Having the BP in the office taken by a nurse or
technician, rather than the clinician, may minimize
the white coat effect.
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 In patients diagnosed as being hypertensive on a first
visit to a new clinician, there is a mean 15 and 7 mmHg
fall in the systolic and diastolic BP, respectively, by the
third visit , with some patients not reaching a stable
value until the sixth visit .
 It is recommended that a patient with mild to
moderate elevation in BP should not be diagnosed
with hypertension unless the BP remains elevated after
three to six visits, unless there is evidence of ongoing
end-organ damage
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 In cross-sectional studies, the prevalence of white coat
hypertension ranges from 10 to more than 20 percent,
and appears to be higher in children and the elderly .
 White coat hypertension can also be seen in patients
with apparently resistant hypertension.
 The likelihood of normal ambulatory pressures is low
(less than 5 percent) in patients with office diastolic
pressures ≥105 mmHg.
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 In one study of nearly 500 treated hypertensive
patients (over 60 percent on three or more
antihypertensive agents), 37 percent had normal BP on
ABPM.
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PROGNOSIS OF WHITE COAT
HYPERTENSION
 The cardiovascular risk associated with white coat
hypertension may be slightly higher compared with
persistent normotension but well below the risks
associated with either masked or sustained
hypertension.
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 In a study of 6000 subjects followed for a median of 5.4
years after having ABPM, stroke rates were
significantly higher in patients with sustained
hypertension compared with those who had persistent
normotension (0.65 versus 0.35 percent per year).
 Stroke rates were also higher in those who had white
coat hypertension (0.59 versus 0.35 percent per year),
but this was not statistically significant.
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 In a population-based cohort of 2051 adults who
underwent office, home, and ambulatory blood
pressure measurements, those with white coat
hypertension had a significantly higher rate of all-cause
mortality during 16 years of follow-up as
compared with persistent normotension (19.7 versus
6.4 percent).
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 Patients with white coat hypertension are also at high
risk for developing sustained hypertension.
 In a study of 81 patients with office hypertension
(mean BP 154/97 mmHg) and normal 12 hour
ambulatory BP (mean BP 125/77 mmHg), 60 had a
mean ambulatory BP above 140/90 mmHg after five to
six years of follow-up (74 percent).
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 Optimal approach to patients with white coat
hypertension is uncertain.
 Careful monitoring is indicated for the possible
development of worsening hypertension or of end-organ
damage, while the patient is encouraged to
modify unhealthy lifestyle habit.
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INDICATIONS FOR ABPM
 In accordance with published practice guidelines and
expert panel recommendations, ambulatory
monitoring should be considered in the following
circumstances :
 Suspected white coat hypertension
 Suspected episodic hypertension
(pheochromocytoma)
 Hypertension resistant to increasing medications
 Hypotensive symptoms while taking antihypertensive
medications
 Autonomic dysfunction
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OTHER POTENTIAL INDICATIONS
 To establish nondipper status or nocturnal
hypertension
 Large variations in self-measured blood pressure
values
 To evaluate whether antihypertensive therapy is
moderating the early morning blood pressure surge
 Elevated office blood pressure in pregnant women,
with preeclampAMsBiUaL AsTOuRsY pBP eMcONtIeTOdRING-SHOULD IT
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 If there is significant hypertension on ABPM, or
resistance to antihypertensive therapy, an
echocardiogram to screen for left ventricular
hypertrophy (LVH) may be indicated, as LVH may be
an early sign of end-organ damage which is otherwise
undetectable.
 Due to issues of cost and inconvenience, ABPM is not
recommended for the evaluation of patients with
uncomplicated hypertension or to screen for
hypertension.
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INFLUENCE ON THERAPY OF
HYPERTENSION
 Therapeutic decisions can be made according to the
ambulatory blood pressure (BP) findings.
 Ambulatory or self-recorded home readings may
detect the early morning BP surge that may contribute
to the increased incidence of sudden death,
myocardial infarction, and stroke in the early morning
hours.
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 Modulation of this early morning surge in BP may not
occur with supposedly long-acting, "once-daily" agents
which do not provide 24-hour coverage.
 Such drugs, including atenolol or enalapril, may lose
much of their effect during the early morning hours,
and therefore may need to be taken twice daily.
 Preferably, long-acting medications with effects that
truly last for 24 hours should be substituted.
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 In those with nocturnal hypertension or nondipping,
ABPM may helps determine the best timing of
administration of antihypertensive agents.
 In one study, valsartan taken before bedtime
reestablished the nocturnal reduction in BP.
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HOME BP MEASUREMENTS
 In view of the cost and limited availability of
ambulatory monitoring, increasing attention is being
given to home monitoring with inexpensive semi-automatic
devices.
 Casual blood pressure (BP) measurements taken at
home or work correlate more closely with the results of
24-hour or daytime ambulatory monitoring than with
the BP taken in the clinician's office .
 Home BP measurements are more predictive of
adverse outcomes (eg, stroke, end-stage renal disease)
than clinic blood pressures.
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GUIDELINES FOR MEASURING
HOME BP  While seated, the patient should take two measurements
(separated by one to two minutes) in the morning and in
the evening (ie, four measurements per day) for at least
three, and preferably seven, consecutive days. These
measurements should be recorded.
 Measurements from the first day should be discarded; the
home blood pressure is defined as the average of all
remaining measurements.
 In stable hypertensive patients with controlled BP, this
same procedure of 12 to 14 measurements taken over one
week should be repeated approximately every three
months to determine whether the BP remains controlled .
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SUMMARY AND
RECOMMENDATIONS
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 The diagnosis of hypertension based upon ABPM
depends upon the time span over which it is
interpreted :
 A 24-hour average above 135/85 mmHg
 Daytime (awake) average above 140/90 mmHg
 Nighttime (asleep) average above 125/75 mmHg
 Cardiovascular complications correlate more closely
with 24-hour or daytime ABPM than with the office
BP.
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 White coat hypertension may be associated with an
increased risk of stroke, possibly related to later
development of sustained hypertension.
 The risk of cardiovascular complications associated
with masked hypertension is similar to that seen with
persistent hypertension.
 Failure of the BP to fall by at least 10 percent during
sleep (nondipping), may also be associated with
increased cardiovascular risk.
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 ABPM may facilitate achieving blood pressure control and reduce
unnecessary treatment.
 ABPM should be considered in the following situations :
 Suspected white coat hypertension
 Suspected episodic hypertension
 Hypertension resistant to increasing medication
 Hypotensive symptoms while taking antihypertensive medications
 Autonomic dysfunction
 Self-recorded home BP measurements are an excellent alternative if
ABPM is not available or cost is a concern.
 Home BP monitoring may also improve hypertension control.
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THANK YOU
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Routine Ambulatory BP Monitoring Benefits

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