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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.
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
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).
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
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