A Review of the Complexities of Morning Hypertension

Dr. Page is an associate professor of clinical pharmacy and physical medicine and a clinical specialist, Division of Cardiology, University of Colorado Health Sciences Center, Schools of Pharmacy and Medicine.

As with most biologic processes, blood pressure (BP) demonstrates a distinct circadian rhythm, characterized by a substantial reduction during sleep (the nocturnal dip) followed by a moderate to marked increase around the time of awakening (the morning surge). It is not surprising that the onset of acute cardiovascular (CV) events (eg, myocardial infarction, sudden cardiac death, and stroke) also shows a circadian pattern, with peak occurrence during the early morning hours.^1,2 In patients with hypertension, this surge in BP (eg, above 135/85 mm Hg) during the first 2 hours after waking, but not in the evening (the last 2 hours before going to bed) has been defined as morning hypertension.³ This morning BP surge has pathological significance as it is positively related to degree of target-organ damage, such as carotid intima-media thickness and left ventricular hypertrophy.^4-6 The magnitude of the morning surge also is an independent predictor of cerebrovascular and cardiac events.⁷

Nondippers Versus Extreme Dippers

Two types of morning hypertension exist.^8-10 The patients who demonstrate a nocturnal decrease in BP that is <10% of their daytime BP are known as nondippers. The other type of patients are the extreme dippers who exhibit a 20% or more decrease in nocturnal BP, compared with daytime BP. Finally, a patient can be an inverted dipper/riser in which their BP does not decrease or actually may increase at night. Nondippers and risers typically do not show a surge in BP on awakening but usually have sustained early morning hypertension. An excessive morning surge is common in extreme dippers.^8-10

What Causes Morning Hypertension?

The morning surge in BP is influenced by many pathophysiological factors, such as activity of the autonomic and renin-angiotensin- aldosterone systems and dietary sodium intake. Other alterations that occur during the early morning that can have a significant impact on increasing CV risk in this population include increased heart rate, vascular tone, blood viscosity, and platelet aggregability. With the advent of ambulatory blood pressure monitoring (ABPM), this technology has improved identification of patients with excessive morning surges and has facilitated assessment of antihypertensive agents that may be particularly effective in this subgroup of the hypertensive population.^11,12

In the Japan Morning Surge-1 study, Ishikawa and colleagues used ABPM in 611 patients with morning hypertension to determine important patient-specific characteristics.¹³ The analysis showed that patients with morning hypertension are more likely to be of older age, as well as have a longer duration of hypertension and antihypertensive medication use, display a higher prevalence of left ventricular hypertrophy with an elevated B-type natriuretic peptide concentration, and exhibit a lower glomerular filtration rate.

As for pharmacotherapy, choice of an agent is dependent upon the pharmacokinetics and formulation of the drug, published evidence, and timing of administration. Medications with long half-lives, such as telmisartan, amlodipine, chlorthalidone, and bisoprolol, have demonstrated efficacy in controlling early morning BP. Bedtime administration of chronotherapeutic preparations as well as alphablockers such as doxazosin have also been effective, particularly when used in combination with ABPM.^14-24

This communication on the importance of home blood pressure monitoring is supported by Omron Healthcare, Inc. It is intended to help pharmacists and their staff understand the importance of home blood pressure monitoring.

References

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