Treatment of hypertension:What are the new standards of care?

Bryan Williams, MDUniversity 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

• 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

90

140ABPM(mmHg)

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

24 hour Ambulatory Blood Pressure

90

140ABPM

(mmHg)

Mean day BP: 152/98

Mean Night BP: 134/85

Mean 24hr BP: 141/92

“Hypertensive”Dipper status: normal

24 hour Ambulatory Blood Pressure

90

140ABPM

(mmHg)

Mean day BP: 148/96

Mean Night BP: 146/96

Mean 24hr BP: 147/96

“Hypertensive”Dipper status: AbnormalMore common in diabetes,CKD and secondary 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 for the Diagnosis of Hypertension

ABPM improves the sensitivity and specificity of 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

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?

± Diagnose Hypertension

Use Mean daytime BP to define hypertension

Offer Ambulatory BPMeasurement (ABPM)Days

or weeks

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

• 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

Head GA, et al. BMJ, 2010

150/95mmHg

135/85mmHg

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