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Treatment of hypertension:
What are the new standards of care?
Bryan Williams, MD
University of Leicester
Leicester, United Kingdom
Clinic vs. ABPM
Clinic BP
• Single reading in controlled time
• Provides a Snapshot
• Predicts Risk
• Tells us nothing about temporal patterns of blood pressure
• Tells us nothing about “quality” of BP control over 24hrs
Clinic BP
• We measure BP in an artificial setting
• We measure BP based on a single heart beat in this
setting, once or twice a year and define the quality of BP
control!
• Patients with “normal office BP” still have strokes and
heart attacks
• But.. Not usually on the doctor’s office!
• We have a poor appreciation of what their usual BP is in
their normal daily life
ABPM
• More readings in a usual setting
• Details of temporal patterns of blood pressure
• Details of impact of treatment on BP parameters over 24hrs
• Better correlated with target organ damage vs. office BP
• Better correlated with Clinical outcomes vs. office BP
• Preferred in Clinical Trials – “regression to the mean and
placebo effect of treatment”
ABPM: Patterns
• Hypertension: 24hr BP load abnormal
• “White Coat Hypertension”: Office BP abnormal, ABPM
normal, no TOD.
• “Masked Hypertension”: Office BP normal, ABPM
abnormal.
• Abnormal nocturnal dipping
• “Nocturnal Hypertension”: Daytime BP normal, nocturnal
BP elevated
ABPM vs. Office BP
• ABPM better correlated with target organ damage and its
response to treatment;
• ABPM has a steeper relationship with CV events;
• ABPM provides a more accurate measure of the response
to treatment – absence of “white coat” and placebo effect;
• Blunted nocturnal dip in BP associated with more target
organ damage and worse clinical outcome;
• BP variability linked to TOD and worse prognosis –
especially for stroke;
Analysis of ABPM
• Mean 24 hour blood pressure
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Mean Daytime blood pressure
Mean Nocturnal Blood Pressure
Day / Night Variability (“Dipper” status)
Blood Pressure “Load”
Morning BP surge*
Blood Pressure Variability*
Ambulatory Stiffness Index (AASI)*
* Emerging indices
24 hour Ambulatory Blood Pressure
Mean day BP: 122/84
Mean Night BP: 117/72
“Normotensive”
Mean 24hr BP: 119/78
Day
ABPM 140
(mmHg)
90
Night
Morning Surge
24 hour Ambulatory Blood Pressure
Mean day BP: 152/98
“Hypertensive”
Mean Night BP: 134/85
Dipper status: normal
Mean 24hr BP: 141/92
140
ABPM
(mmHg)
90
24 hour Ambulatory Blood Pressure
Mean day BP: 148/96
140
ABPM
(mmHg)
90
“Hypertensive”
Mean Night BP: 146/96
Dipper status: Abnormal
Mean 24hr BP: 147/96
More common in diabetes,
CKD and secondary hypertension
ABPM for the Diagnosis of Hypertension
• ABPM is a better predictor of clinical outcomes than
clinic BP;
• ABPM is the reference standard used in clinical
practice when there is uncertainty about the diagnosis;
• ABPM improves the specificity and sensitivity of
diagnosis versus clinic and home BP measurement;
• Avoids treatment in people who are not
hypertensive – as many as 25% with “white coat
hypertension”;
ABPM improves the sensitivity and
specificity of diagnosis of hypertension
ABPM for the Diagnosis of Hypertension
• Was cost effective (cost saving to the NHS) versus
clinic and home BP measurement;
• Home BP is an alternative for those who do not tolerate
ABPM but it is not as good as ABPM;
• Automated devices cannot be used for people with
significant pulse irregularity – e.g. Atrial fibrillation – use
manual auscultation in such patients:
ABPM for the diagnosis of hypertension
• No convincing evidence that night-time BP or 24hr BP
is superior to daytime BP averages in predicting risk –
more data needed;
• When using ABPM to confirm a diagnosis of
hypertension, ensure that at least two measurements
per hour are taken during normal waking hours (for
example, daytime between 08:00 and 22:00);
• Use the average of these waking hours blood pressure
measurements to confirm a diagnosis of hypertension;
The Lancet, August 2011
How should hypertension be diagnosed?
New Guidance 2011
Screening BP – High?
Days
or
weeks
Offer Ambulatory BP
Measurement (ABPM)
Use Mean daytime BP to define
hypertension
± Diagnose Hypertension
CVD Risk
&
TOD
Assessment
ABPM - Methodology
Timing of blood pressure measurements
• Day (usually): 0800hrs - 2200hrs
• Day measurements: every 30 minutes
• Average of at least 14 measurements to
define Daytime ABPM average
ABPM and Target Organ Damage
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Left Ventricular Mass
Systolic and diastolic cardiac dysfunction
Carotid IMT
Cerebral infarction by MRI
Presence of microalbuminuria
Changes in retinal vasculature
Total Target Organ Damage score
“ABPM is superior to office BP at predicting
cardiovascular/renal target organ damage”
Webb AJS, et al. Lancet 2010.
Group distribution (SD and CV) of measures of SBP at
baseline and at each follow-up visit in the
two treatment groups
Rothwell P, et al. Lancet 2010
• 24-hour ABPM in 5682 participants (mean age 59.0 years; 43.3% women);
• Prospective population studies in Europe and Japan;
• Determined ABPM thresholds, which yielded 10-year cardiovascular risks
similar to those associated with optimal (120/80 mm Hg), normal (130/85
mm Hg), and high (140/90 mm Hg) blood pressure on office measurement.
Circulation. 2007;115:2145-2152.
ABPM: Normal vs. Abnormal
Kikuya M, et al. Circulation 2007; 115: 2145–52
ABPM Thresholds and targets
Systolic/Diastolic ABPM values predicted from seated clinic BP levels
150/95mmHg
135/85mmHg
Head GA, et al. BMJ, 2010
Conclusions
• New NICE guidelines recommend the routine use of
ABPM to confirm the diagnosis of hypertension
• The biggest change to the diagnosis of hypertension for
more than 100 years
• ABPM improves the specificity and sensitivity of
diagnosis
• This approach is highly cost-effective
• New technologies are being developed that will improve
the acceptability of ABPM
• Costs of devices is likely to fall