1. Treatment of hypertension: What are the new standards of care?
Bryan Williams, MD
University of Leicester
Leicester, United Kingdom

2. 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

3. 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

4. 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”

5. 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

6. 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;

7. Analysis of ABPM Mean 24 hour blood pressure
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

8. 24 hour Ambulatory Blood Pressure
Mean day BP: 122/84
Mean Night BP: 117/72
Mean 24hr BP: 119/78
“Normotensive”
Day
Night
Morning Surge
140
ABPM
(mmHg) 90

9. 24 hour Ambulatory Blood Pressure
Mean day BP: 152/98
Mean Night BP: 134/85
Mean 24hr BP: 141/92
“Hypertensive”
Dipper status: normal
140
ABPM
(mmHg) 90

10. 24 hour Ambulatory Blood Pressure
Mean day BP: 148/96
Mean Night BP: 146/96
Mean 24hr BP: 147/96
“Hypertensive”
Dipper status: Abnormal
More common in diabetes,
CKD and secondary hypertension
140
ABPM
(mmHg) 90

11. 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”;

12. ABPM improves the sensitivity and specificity of diagnosis of hypertension

13. 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:

14. 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;

15. The Lancet, August 2011

16. How should hypertension be diagnosed?
New Guidance 2011
Days or
weeks
Screening BP – High?
CVD Risk
&
TOD
Assessment
Offer Ambulatory BP
Measurement (ABPM)
Use Mean daytime BP to define hypertension
± Diagnose Hypertension

17. ABPM - Methodology Timing of blood pressure measurements
Day (usually): 0800hrs hrs
Day measurements: every 30 minutes
Average of at least 14 measurements to
define Daytime ABPM average

18. ABPM and Target Organ Damage
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”

19. Webb AJS, et al. Lancet 2010.

20. 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

21. 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:

22. ABPM: Normal vs. Abnormal
Kikuya M, et al. Circulation 2007; 115: 2145–52

24. ABPM Thresholds and targets
Systolic/Diastolic ABPM values predicted from seated clinic BP levels
150/95mmHg
135/85mmHg
Head GA, et al. BMJ, 2010

25. 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