High blood pressure (BP) is defined as having a persistently high systolic blood pressure (SBP) and/or diastolic blood pressure (DBP) reading. The diagnostic criterion outlined by the American College of Cardiology/American Heart Association (ACC/AHA) Task Force suggest using an average of two or more BP readings obtained on two or more occasions to estimate an individual’s BP.1 This recommendation stems from the fact that BP fluctuates throughout the day based on a variety of factors, including the time of day, waking vs sleeping, changes in activity, body and arm movement, smoking cigarettes, work and environmental stress, driving, use of antihypertensive medications, and other stimuli.2,3 The level of this variation can differ from person to person based on both genetic and environmental influences.
Conditions such as atrial fibrillation and other arrythmias are also associated with short-term spikes in BP.3 There is limited evidence regarding the significance of BP spikes in this population, and further investigation is needed.
Long-Term Variability
While some degree of short-term variability may be normal, long-term variability has been linked with poorer outcomes. A 2016 meta-analysis that assessed the cardiovascular (CV) significance of BP variability found no significant association between short-term variability, measured by ambulatory BP monitoring, and CV disease events or mortality.6 However, long-term variability was associated with increased risk of both CV disease events and cardiovascular disease mortality.
One study analyzing the United Kingdom Transient Ischemic Attack (UK-TIA) Trial cohort data (n=1,259) found that while low visit-to-visit variability in SBP didn’t significantly affect CV disease risk, high variability was associated with increased risk for both stroke and coronary events.7 Incidence of vascular events was similar between those with stable normotension and stable hypertension (12.9% vs 13.0%). However, those with moderate episodic hypertension (defined as at least one reading ≤140 mmHg, one reading >140 mmHg, but none exceeding 180 mmHg) had a 17.1% incidence of vascular events, and those with episodic severe hypertension (at least one reading ≤140 mmHg and at least one reading ≥180 mmHg) had a 28.5% incidence.
Sustained volitality in BP, particularly at night, is associated with an increase in CV morbidity and mortality. One study following hypertensive patients (n=2,649) over 16 years found that greater nocturnal variability in SBP increased risk for cardiac events by 0.38 per 100 person-years (p=0.024).8 Those who experienced cardiac events had a 1.8 mmHg (11.3 vs 13.1) higher standard deviation in nighttime SBP and 0.8 mmHg (9.3 vs 10.1) higher standard deviation in nighttime DBP, representing a 0.27% increase in absolute cardiacevent risk when SBP nighttime variability increased by 1 mmHg and a 0.13% increase in risk for increased DBP variability.
Severe Variability
Severe spikes in BP are known as hypertensive crises, defined as SBP ≥180 mmHg or DBP ≥120 mmHg.9 Hypertensive crises are further classified into hypertensive urgencies, which are asymptomatic and not associated with end-organ damage, and hypertensive emergencies, which are associated with new or progressive end-organ damage.
In individuals with hypertensive urgency, the rate of major adverse CV events within 6 months is less than 1%.10 In the absence of end-organ damage, there is no indication for hospitalization or referral to the emergency department. ACC/AHA guidelines state that these individuals should be managed by reinstituting or intensifying their antihypertensive medications and following up on an outpatient basis.9
In people with hypertensive emergency, manifestations of end-organ damage can include life-threatening conditions such as stroke, myocardial infarction, acute left-ventricular failure with pulmonary edema, unstable angina pectoris, and dissecting aortic aneurysm. If untreated, the one-year mortality rate is greater than 79% and the median survival is 10.4 months.9 ACC/AHA guidelines recommend admission to an intensive care unit.9
References
- Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. Jun 2018;71(6):1269-1324. doi:10.1161/HYP.0000000000000066
- O'Brien E, Parati G, Stergiou G, et al. European Society of Hypertension position paper on ambulatory blood pressure monitoring. Journal of hypertension. Sep 2013;31(9):1731-68. doi:10.1097/HJH.0b013e328363e964
- Parati G, Stergiou G, O'Brien E, et al. European Society of Hypertension practice guidelines for ambulatory blood pressure monitoring. Journal of hypertension. Jul 2014;32(7):1359-66. doi:10.1097/HJH.0000000000000221
- Chadachan VM, Ye MT, Tay JC, Subramaniam K, Setia S. Understanding short-term blood-pressure-variability phenotypes: from concept to clinical practice. Int J Gen Med. 2018;11:241-254. doi:10.2147/IJGM.S164903
- Mena LJ, Felix VG, Melgarejo JD, Maestre GE. 24-Hour Blood Pressure Variability Assessed by Average Real Variability: A Systematic Review and Meta-Analysis. J Am Heart Assoc. Oct 19 2017;6(10)doi:10.1161/JAHA.117.006895
- Stevens SL, Wood S, Koshiaris C, et al. Blood pressure variability and cardiovascular disease: systematic review and meta-analysis. BMJ. Aug 9 2016;354:i4098. doi:10.1136/bmj.i4098
- Rothwell PM, Howard SC, Dolan E, et al. Prognostic significance of visit-to-visit variability, maximum systolic blood pressure, and episodic hypertension. Lancet. Mar 13 2010;375(9718):895-905. doi:10.1016/S0140-6736(10)60308-X
- Verdecchia P, Angeli F, Gattobigio R, Rapicetta C, Reboldi G. Impact of blood pressure variability on cardiac and cerebrovascular complications in hypertension. Am J Hypertens. Feb 2007;20(2):154-61. doi:10.1016/j.amjhyper.2006.07.017
- Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. Jun 2018;71(6):e13-e115. doi:10.1161/HYP.0000000000000065
- Patel KK, Young L, Howell EH, et al. Characteristics and Outcomes of Patients Presenting With Hypertensive Urgency in the Office Setting. JAMA Intern Med. Jul 1 2016;176(7):981-8. doi:10.1001/jamainternmed.2016.1509
