IV. Ambulatory BP Measurement

Diagnosis and Assessment

Subgroup Members: Mark Gelfer, MD; Lyne Cloutier, RN, PhD; Sheldon Tobe, MD, MSc(HPTE); Maxime Lamarre-Cliche, MD; Peter Bolli, MD; Guy Tremblay, MD; Donna McLean, RN, NP, PhD; Alain Milot, MD, MSc; Raj Padwal, MD, MSc; Karen Tran, MD
Central Review Committee: Stella S. Daskalopoulou, MD, PhD; Kaberi Dasgupta, MD, MSc; Kelly B. Zarnke, MD, MSc; Kara Nerenberg, MD, MSc; Alexander A. Leung, MD, MPH; Kevin C. Harris, MD, MHSc; Kerry McBrien, MD, MPH; Sonia Butalia, BSc, MD; Meranda Nakhla, MD, MSc
Chair: Doreen M. Rabi, MD, MSc

This information is based on the Hypertension Canada guidelines published in Leung, Alexander A. et al. Hypertension Canada’s 2017 Guidelines for Diagnosis, Risk Assessment, Prevention, and Treatment of Hypertension in Adults. Can J Cardiol 2017; 33(5): 557-576.

Guidelines

  1. Ambulatory BP monitoring can be used in the diagnosis of hypertension (Grade C). Ambulatory BP monitoring should be considered when an office-induced increase in BP is suspected in treated patients with:
    1. BP that is not below target despite receiving appropriate chronic antihypertensive therapy (Grade C);
    2. Symptoms suggestive of hypotension (Grade C); or
    3. Fluctuating office BP readings (Grade D).
  2. Ambulatory BP monitoring upper arm devices that have been validated independently using established protocols must be used (see www.dableducational.org) (Grade D).
  3. Therapy adjustment should be considered in patients with a mean 24-hour ambulatory BP monitoring SBP of ≥130 mmHg or DBP of ≥80 mmHg, or a mean awake SBP of ≥135 mm Hg and/or DBP of ≥85 mmHg (Grade D).
  4. The magnitude of changes in nocturnal BP should be taken into account in any decision to prescribe or withhold drug therapy based on ambulatory BP monitoring (Grade C) because a decrease in nocturnal BP of <10% is associated with increased risk of cardiovascular events.

Background

1. Ambulatory BP monitoring can be used in the diagnosis of hypertension (Grade C). Ambulatory BP monitoring should be considered when an office-induced increase in BP is suspected in treated patients with:

i. BP that is not below target despite receiving appropriate chronic antihypertensive therapy (Grade C);

ii. Symptoms suggestive of hypotension (Grade C); or

iii. Fluctuating office BP readings (Grade D).

ABPM is the gold standard test for diagnosing white coat hypertension and should be performed if this entity is suspected (1,2). Possible clues to the presence of white coat hypertension are apparent resistant or refractory hypertension, symptoms suggestive of hypotension and labile hypertension(2). In cases where mean office readings and mean ABPM readings are discrepant, ABPM should be used to inform treatment modifications or lack thereof. Elevated ABPM readings are a strong predictor of mortality and cardiovascular events independent of office BP, including in patients with treated hypertension (3-6).

In 688 patients followed up for a mean of 9.2 years, Khattar et al (5) found that the mean 24 h, day- time and night-time ambulatory blood pressure significantly predicted cardiovascular morbidity, whereas the clinical systolic and diastolic blood pressure did not. For 808 older patients (60 years or older) with untreated systolic hypertension followed up for a mean of 4.4 years in a substudy of the Systolic Hypertension in Europe (SYST-EUR) trial, ambulatory blood pressure was a significant predictor of cardiovascular risk over and above clinical blood pressure (6).

2. Ambulatory BP monitoring upper arm devices that have been validated independently using established protocols must be used (see www.dableducational.org) (Grade D).

Published international protocols are used to determine if new ABPM devices can validly assess blood pressure (7,8). An up-to-date list of validated devices can be found at www.dableducational.org. Devices that have not met these validation criteria are not recommended.

3. Therapy adjustment should be considered in patients with a mean 24-hour ambulatory BP monitoring SBP of ≥130 mmHg or DBP of ≥80 mmHg, or a mean awake SBP of ≥135 mm Hg and/or DBP of ≥85 mmHg (Grade D).

These widely accepted 24-hour ambulatory blood pressure thresholds have been derived from prognostic studies examining cardiovascular morbidity and mortality endpoints (9-13).

Table 1. Standardized protocol for amulatory BP monitoring (Grade D)
The appropriate sized cuff should be applied to the nondominant arm unless the SBP difference between arms is >10 mm Hg, in which case the arm with the highest value obtained should be used.
The device should be set to record for a duration of at least 24 hours with the measurement frequency set at 20 – 30 minute intervals during the day and 30-60 minutes at night.
A patient-reported diary to define daytime (awake), night-time (sleep), activities, symptoms and medication administration is useful for study interpretation.
Daytime and night-time should preferentially be defined using the patient’s diary. Alternatively, pre-defined thresholds can be used (e.g. 08:00 to 22:00 for daytime and 22:00 to 8:00 for night-time).
The ABPM report should include all of the individual BP readings (numerically and graphically), the percentage of successful readings, the averages for each time frame (daytime, night-time, 24 hours) and the “dipping” percentage (the percentage the average BP changed from daytime to night-time).
Criteria for a successful ABPM study are:

  • At least 70% of the readings are successful AND
  • At least 20 daytime readings and 7 night-time readings are successful

4. The magnitude of changes in nocturnal BP should be taken into account in any decision to prescribe or withhold drug therapy based on ambulatory BP monitoring (Grade C) because a decrease in nocturnal BP of <10% is associated with increased risk of cardiovascular events.

Patients who fail to exhibit a nocturnal decline in systolic or diastolic blood pressure of 10% or more during sleep are characterized as ‘non-dippers’ (14). Non-dipping portends an increased risk of cardiovascular morbidity and mortality (15-18) and is more common in patients with advanced age, obesity, diabetes, high salt intake, secondary hypertension, prior cardiovascular disease and pre-existing chronic kidney disease (19).

This recommendation advises clinicians to consider non-dipping status when assessing risk status and if debating whether or not pharmacotherapy should be initiated. A firmer recommendation to prescribe antihypertensive therapy in all non-dippers or to convert patients from non-dippers to dippers by prescribing antihypertensive therapy at bedtime cannot be made at this time. Although one relatively large RCT (n=2156) from Spain found that bedtime administration of one or more antihypertensive drugs substantially reduced cardiovascular morbidity and mortality, methodological concerns precluded a recommendation based on this study (20). Further confirmation from additional rigorously performed RCTs is needed.

References

  1. Muxfeldt ES, Bloch KV, Nogueira AR, Salles GF. Twenty-four hour ambulatory blood pressure monitoring pattern of resistant hypertension. Blood Press Monit 2003;8:181-185.
  2. O’Brien E, Parati G, Stergiou G, Asmar R, Beilin L, Bilo G, Clément D, de la Sierra A, de Leeuw P, Dolan E, Fagard R, Graves J, Head G, Imai Y, Kario K, Lurbe E, Mallion JM, Mancia G, Mengden T, Myers M, Ogedegbe G, Ohkubo T, Omboni S, Palatini P, Redon J, Ruilope LL, Shennan A, Staessen JA, vanMontfrans G, Verdecchia P, Waeber B, Wang J, Zanchetti A, Zhang Y. European Society of Hypertension position paper on ambulatory blood pressure monitoring. J Hypertens 2013;31:1731-1768.
  3. Clement DL, De Buyzere ML, De Bacquer DA, et al. Prognostic value of ambulatory blood- pressure recordings in patients with treated hypertension. N Engl J Med 2003;348:2407-15.
  4. Verdecchia P, Porcellati C, Schillaci G, Borgioni C, Ciucci A, Battistelli M, et al. Ambulatory blood pressure. An independent predictor of prognosis in essential hypertension. Hypertension 1994;24:793-801.
  5. Khattar RS, Swales JD, Banfield A, Dare C, Senior R, Lahiri A. Prediction of coronary and cerebrovascular morbidity and mortality by direct continuous ambulatory blood pressure monitoring in essential hypertension. Circulation 1999;100:1071-6.
  6. Staessen ]A, Thijs L, Fagard R, et al. Predicting cardiovascular risk using conventional vs. ambulatory blood pressure in older patients with systolic hypertension. Systolic Hypertension in Europe Trial Investigators. JAMA 1999;282:539-46.
  7. Association for the Advancement of Medical Instrumentation. ANSI/AAMI/ISO 81060-2:2013 Non-invasive sphygmomanometers – Part 2: Clinical investigation of automated measurement type. 2013.
  8. O’Brien E, Atkins N, Stergiou G, Karpettas N, Parati G, Asmar R, Imai Y, Wang J, Mengden T, Shennan A, Working Group on Blood Pressure Monitoring of the European Society of Hypertension. European Society of Hypertension International Protocol revision 2010 for the validation of blood pressure measuring devices in adults. Blood Press Monit 2010;15:23-38.
  9. Verdecchia P, Reboldi G, Porcellati, et al. Risk of cardiovascular disease in relation to achieved office and ambulatory blood pressure control in treated hypertensive subjects. J Am Coll Cardiol 2002;39:878-85.
  10. Ohkubo T, Imai Y, Tsuji I. Prediction of mortality by ambulatory blood pressure monitoring versus screening blood pressure measurements: a pilot study in Ohasama. J Hypertens 1997;15:357-64.
  11. Verdecchia P, Porcellati C, Schillaci G, Borgioni C, Ciucci A, Battistelli M, et al. Ambulatory blood pressure. An independent predictor of prognosis in essential hypertension. Hypertension 1994;24:793-801.
  12. O’Brien E, Parati G, Stergiou G, Asmar R, Beilin L, Bilo G, Clément D, de la Sierra A, de Leeuw P, Dolan E, Fagard R, Graves J, Head G, Imai Y, Kario K, Lurbe E, Mallion JM, Mancia G, Mengden T, Myers M, Ogedegbe G, Ohkubo T, Omboni S, Palatini P, Redon J, Ruilope LL, Shennan A, Staessen JA, vanMontfrans G, Verdecchia P, Waeber B, Wang J, Zanchetti A, Zhang Y. European Society of Hypertension position paper on ambulatory blood pressure monitoring. J Hypertens 2013;31:1731-1768.
  13. Ohkubo T, Imai Y, Tsuji I, etal. Reference values for 24-hour ambulatory blood pressure monitoring based on a prognostic criterion: the Ohasama Study. Hypertension 1998;32:255-9.
  14. O’Brien E, Sheridan J, O’Malley K. Dippers and non-dippers. Lancet 1988;ii:397.
  15. Ohkubo T, Hozawa A, Yamaguchi J, Kikuya M, Ohmori K, Michimata M,
    et al. Prognostic significance of the nocturnal decline in blood pressure in subjects with and without high 24-hour blood pressure: the Ohasama study. J Hypertens 2002; 20:2183–2189.
  16. Staessen JA, Thijs L, Fagard R, O’Brien ET, Clement D, de Leeuw PW, et al. Predicting cardiovascular risk using conventional versus ambulatory blood pressure in older patients with systolic hypertension. JAMA 1999; 282:539 – 546.
  17. Verdecchia P, Porcellati C, Schillaci G, Borgioni C, Ciucci A, Battistelli M, et al. Ambulatory blood pressure. An independent predictor of prognosis in essential hypertension. Hypertension 1994; 24:793–801.
  18. Verdecchia P, Porcellati C, Schillaci G, Borgioni C, Ciucci A, Battistelli M, et al. Ambulatory blood pressure. An independent predictor of prognosis in essential hypertension. Hypertension 1994;24:793-801.
  19. de la Sierra A, Redon J, Banegas JR, Segura J, Parati G, Gorostidi M, de la Cruz JJ, Sobrino J, Llisterri JL, Alonso J, Vinyoles E, Pallare ́s V, Sarría A, Aranda P, Ruilope LM, on behalf of the Spanish Society of Hypertension Ambulatory Blood Pressure Monitoring Registry Investigators. Prevalence and factors associated with circadian blood pressure patterns in hypertensive patients. Hypertension 2009;53:466–472.
  20. Hermida RC, Ayala DE, Mojón A, Fernández JR. Influence of circadian time of hypertension treatment on cardiovascular risk: results of the MAPEC study. Chronobiol Int 2010;27:1629-1651.