ABPM Interpretation &

Hard To Manage BP

Dr Mel Lobo PhD FRCP

Director Barts Blood Pressure Clinic

Bart’s Health NHS Trust

NIHR Barts Cardiovascular Biomedical Research Unit

William Harvey Research Institute, QMUL

NIHR Bart’s and The London

Cardiovascular Biomedical Research Unit

William Harvey

Research Institute

OBSERVER

BIAS

DIGIT PREFERENCE

INATTENTION

RAPPORT

HEARING & VISION

DISTANCE

CUFF/BLADDER

CUFF CONDITION

APPLICATION

BLADDER SIZE

BLADDER POSITION

RIGHT OR LEFT?

SPHYGMOMANOMETER

HEIGHT

POSITION & TILT

LEVEL OF HG

MAINTENANCE

STETHOSCOPE

SUBJECT

ANXIETY

RECENT EXERCISE

MEAL OR TOBACCO

OBESITY

ELDERLY

ARRHYTHMIA

POSTURE

ARM LEVEL

ARM SUPPORT

LOCATION

TEMPERATURE

HUMIDITY

NOISE

CONVENTIONAL BP MEASUREMENT

BP MEASUREMENT: KEY TECHNIQUES

BP (mm Hg) if not done

Rest ≥ 5 min, quiet ↑ 12/6

Seated, back supported ↑ 6/8

Cuff at midsternal level ↑ ↓ 2/inch

Correct cuff size (undercuffing) ↑ 6-18/4-13

Bladder center over artery ↑ 3-5/2-3

Deflate 2 mm Hg/sec ↑ SBP/↓ DBP

If initial BP > goal BP: 1st reading higher

3 readings, 1 min apart “Alerting response”

Discard 1st, average last 2

Hypertension 2005; 45:142 J Hypertens 2005; 23:697 Can J Card 2007; 23:529

If the clinic blood pressure is 140/90 mmHg or higher,

offer ambulatory blood pressure monitoring (ABPM) to

confirm the diagnosis of hypertension.

Evidence ABPM is superior to clinic blood pressure

and in most studies home blood pressure monitoring

for diagnosis

ABPM is gold standard – HBPM is a less good

alternative if not available or possible

NICE 2011

Diagnosis of hypertension (1)

When using the following to confirm diagnosis, ensure:

ABPM:

– at least two measurements per hour during the

person’s usual waking hours, average of at least 14

measurements to confirm diagnosis

HBPM:

– two consecutive seated measurements, at least 1

minute apart

– blood pressure is recorded twice a day for at least 4

days and preferably for a week

– measurements on the first day are discarded –

average value of all remaining is used.

NICE 2011

Diagnosis of Hypertension(2)

Definitions

Stage 1 hypertension:

• Clinic blood pressure (BP) is 140/90 mmHg or higher and

• ABPM or HBPM average is 135/85 mmHg or higher.

Stage 2 hypertension:

• Clinic BP 160/100 mmHg is or higher and

• ABPM or HBPM daytime average is 150/95 mmHg

or higher.

Severe hypertension:

• Clinic BP is 180 mmHg or higher or

• Clinic diastolic BP is 110 mmHg or higher.

ABPM – the origins...

ABPM 2012

Case examples

Standard ABPM report – normal BP result

Daytime Mean 128/78 mm Hg

Nocturnal Mean 110/62 mm Hg

OFFICE HYPERTENSION

156/88 mmHg

White COAT HYPERTENSION20 -25% hypertensive population

AMBULATORY NORMOTENSION

128/68 mmHg

The ABPM shows marked white-coat hypertension

(205/100 mmHg) with otherwise normal 24-hour

systolic & diastolic blood pressure (128/68 mmHg

daytime and 112/54 mmHg night-time).

© 2011 dabl® Limited

OBP 156/88 mm Hg

Initial ABPM reading 205/100 mm Hg

Daytime Mean 128/68 mm Hg

Nocturnal Mean 112/54 mm Hg

White coat hypertension

Initial ABPM reading 175/95 mm Hg

Daytime Mean 133/71 mm Hg

Nocturnal Mean 119/59 mm Hg

********************

White coat effect

Initial ABPM reading 187/104 mm Hg

Daytime Mean 149/87 mm Hg

Nocturnal Mean 121/67 mm Hg

Hypertension – varying severity

D. Borderline

DM 135/57 mm Hg

NM 132/81 mm Hg

E. Moderate systo-diastolic HTN

DM 147/93 mm Hg

NM 111/66 mm Hg

F. Severe systo-diastolic HTN

DM 164/112 mm Hg

NM 157/101 mm Hg

Isolated Systolic Hypertension

Daytime Mean 176/68 mm Hg

Nocturnal Mean 169/70 mm Hg

DIPPING PATTERN

Daytime Mean 181/117 mm Hg

Nocturnal Mean 111/68 mm Hg

NON-DIPPING PATTERN

© 2011 dabl® Limited

The ABPM shows severe 24-hour systolic & diastolic hypertension

(210/134 mmHg daytime and 205/130 mmHg night-time).

Hypotension

Masked Hypertension

WHITE COAT HYPERTENSION

20 – 25%

MASKED HYPERTENSION

10 – 15%

CBPM ~ INCORRECT DIAGNOSIS

30 – 40%

Ambulatory Blood Pressure – uncovers the truth!

Standardising ABPM reporting

Report (requires 14 day time readings to be completed)

• Record name of patient and date of study

• Daytime Mean and heart rate then night time mean and heart rate

• Comment on presence/absence of nocturnal dipping

• Presence/absence of white coat effect (note the highest WC BP)

• Comment on BP variability (SD of mean)

• The 24 hr ABPM on Mr XX was done on 1.8.2014 and showed a daytime mean of

132/78 mm Hg with a heart rate of 85 bpm. There was well preserved nocturnal

dipping to an ideal mean of 119/72 mm Hg with HR of 65 bpm. There was

pronounced white coat effect with an initial reading of 178/105 mm Hg. The study

demonstrated physiological variability of ABP and DBP during the day and night.

• Conclusion – this study demonstrates white coat hypertension with high resting HR

A few words about

hard to manage BP

Global definitions of RHTN

Messerli and Bangalore. European Heart Journal (2013) 34;1175-1177

Epidemiology of Resistant Hypertension

• Incidence of resistant hypertension is 0.7 per 100 patient years

• Estimated prevalence rates are varied

Due to different definitions of resistant hypertension

Up to 35% in post-hoc analyses of major outcome trials (LIFE, ALLHAT, ASCOT)

8-20% in cohort studies

Daugherty SL et al., Circulation 2012; 125: 1635-1642

Daugherty SL et al., Circulation 2012; 125: 1635-1642de la Sierra A et al., Hypertension 2011; 57: 898-902Persell SD, Hypertension 2011; 57: 1076-1080

Epidemiology of Hypertension in the UK

£1 billion/pa direct drug costs

12% of all primary care consultations are regarding HTN

12 million hypertensive adults in the UK

8 million are diagnosed

7 million are treated

4 million are treated <140/90 mmHg

2.8 million are treated but not to target

~0.5-0.8 million are resistant (6-10% of treated HTN)

Health Survey England, 2011; hscic.gov.uk/pub09300NICE CG127, 2011; guidance.nice.org.uk/cg127

Increased Cardiovascular Risk in RHTN

Pierdomenico SL et al., Am J Hyp 2005; 18: 1422-1428

***

CV EVENTS:

Fatal/non-fatal MI

Coronary revascularisation

Peripheral revascularisation

Hospitalised heart Failure

Fatal/non-fatal stroke

CKD requiring dialysis

Strategies for medical evaluation

Before committing your patient to further investigation and

additional antihypertensive medication decide:

• Is this true RHTN or is this pseudoresistance?

• Risk factors for RHTN» Older age >75 yrs

» Females

» Black ethnicity

» Higher baseline BP and chronic uncontrolled HTN

» Diabetes

» Obesity

» Atherosclerotic vascular disease and aortic stiffening

» Existing target organ damage: LVH, CKD, retinopathy

» Excessive salt intake

Factors associated with Pseudo- Resistant Hypertension

Inappropriate BP measurementUnder-cuffingUse of automated methods in arrhythmiasLack of ABP to r/o WCH

Physician inertia

Inappropriate medication classes/doses

Suboptimal consultations

White coat effect

Non-adherence to therapy

Poor concordanceMedication intolerance

Lifestyle issues

Costs of drugs

Physician-related Patient-related

Myat et al. BMJ 2012;345:e7473

Clinic reading 168/92 mm Hg

Daytime Mean 117/77 mm Hg

Investigation for secondary causes

• Investigate pts with resistant hypertension for secondary

causes

• Choices of investigation modalities used to be very much

centre-oriented – less so now

• Detailed assessment is best undertaken in dedicated specialist

centres (BHS Hypertension Centres of Excellence)

Medical treatment strategies (1)

Effect for lifestyle interventionsIntervention Average

red’n in

SBP &

DBP

% with

10mmHg

red’n in SBP

(<1 year)

Other comments

(from NICE guideline 2006)

Diet

(healthy, low-calorie)

5-6mmHg ~40% Average weight changes were

from 2-9 Kg

Exercise

(Aerobic 30-60 min, 3-5x wk)

2-3mmHg ~30%

Relaxation therapy

(structured)

3-4mmHg ~33% Cost in primary care unknown.

Availability?

Multiple interventions 4-5mmHg ~25% Education alone unlikely to be

effective

Alcohol reduction

(structured)

3-4mmHg ~30% <21 units/wk men, 14 units/wk

women raised BP, poorer

health

Salt reduction

(<6g/day)

2-3mmHg ~25% Effects diminish over time (2-3

years)

Other: Caffeine (5 cups coffee) increase BP by ~2/1 mmHg; Smoking (per se) has no effect on

BP; Mineral supplements — no robust evidence

Salt restriction is highly effective in RHTN

• 12 subjects with RHTN in a randomised cross-over study

• Low salt (3g daily) vs high salt (15 g daily) diet for 7 days separated by 2/52 washout

Pimenta et al., Hypertension 2009;54:475-481

High salt Low salt *Mean

change

Comparison of ABPM values

* All changes highly significant

NIHR Barts and The London CVBRU

Centre for Advanced Cardiovascular Imaging

NIHR Barts and The London

Cardiovascular Biomedical Research Unit

William Harvey

Research Institute

In conclusion...

• Hypertension diagnosis now requires ABPM or HBPM

• Standardise reporting of ABPM – it will be easier to interpret!

• Patients are keen to adopt HBPM but need to be properly educated

in BP measurement

• Difficult hypertension can be treated with α/β-blockers/spironolactone but

best to refer to specialist clinic