This article is more than 5 years old. Information may no longer be current.
Blog: Masked Hypertension and White-Coat Hypertension–Therapeutic Navigation between Scylla and Charybdis
Click Here to Manage Email Alerts
BP is a labile hemodynamic parameter; it varies from heartbeat to heartbeat, from morning to evening, from winter to summer, from sleeping to awake and from sitting to standing. The same holds true for any other CV hemodynamic parameter such as heart rate, cardiac output, ejection faction or pulmonary wedge pressure. However, the information that is based on invasively obtained measurements is often considered more reliable than information based on simple BP recording.
Numerous studies have documented that BP, when measured carefully under standardized conditions in physicians’ offices, is a powerful and reliable predictor of morbidity and mortality. Recent studies have documented that 24-hour ambulatory BP monitoring is even a closer surrogate endpoint for heart attack and stroke than is office BP. Because the correlation between 24-hour ambulatory BP measurement and office BP measurement is moderate at best, it’s not unexpected that there will be a significant number of people who are truly hypertensive but in whom the diagnosis is missed by BP measurement in the office setting (masked hypertension). Conversely, BP may be elevated in the office but not on ambulatory BP monitoring — an entity known to most clinicians as white-coat hypertension.
Distinct differences
White-coat hypertension is a well-known clinical entity familiar to most physicians. A variety of studies have shown that the risk in patients with white-coat hypertension is somewhat elevated but distinctly lower than in patients who have sustained hypertension. Despite its commonness, little is known how to best manage white-coat hypertension. Out of fear of over-treatment, some physicians are taking a “wait and see approach” in patients with white-coat hypertension. Conversely, out of fear of litigation, some physicians may take an over-aggressive therapeutic approach, which may lead to hypotension and orthostatic symptoms.
Franz H. Messerli
In stark contrast, masked hypertension is a much less well-known (but not necessarily a less common) entity, which seems to carry a distinctly more serious prognosis. This was documented by Pickering and colleagues, who were the group that proposed the term “masked hypertension.” The same entity has been described occasionally as “reversed white-coat hypertension.” It was initially regarded as rare but was recently found to be present (to some extent) in about one-third of the hypertensive population. Risk factors for masked hypertension include alcohol, tobacco, caffeine and physical inactivity.
In the PAMELA population, patients with masked hypertension have a prevalence of echocardiographic left ventricular hypertrophy that was much greater than that of normotensive patients. Inappropriate target organ disease (ie, inappropriate for office BP) should, therefore, trigger suspicion of masked hypertension and motivate physicians to expose a susceptible patient to 24-hour ambulatory BP monitoring.
Difficulties detecting masked hypertension
The clinician should remember that it’s much easier to suspect the diagnosis of white-coat hypertension, as patients will usually tell that the BP is normal at home. In contrast, masked hypertension needs to be looked for, and there are few clinical hints as to its presence. Normal BP in the clinical setting does not mean that a patient is not at risk for an elevated BP, which can occur at other times of the day.
This is particularly true in patients who are treated with antihypertensive drugs that are not covering a full 24-hour period such as atenolol (Tenormin, AstraZeneca), losartan (Cozaar, Merck) and hydrochlorothiazide. Because the patient takes the medication in the morning, BP values in the physician’s office most often are normal but may be substantially elevated at the end of the dosing interval (ie, during the night and early morning hours). Thus, in many hypertensive patients, clinic BP is seemingly well-controlled, but morning BP, before taking the medication, may be elevated, thereby exposing the patient to a high risk of CV events. Unfortunately, masked hypertension has become a blind spot in the current management of this disease.
Although we certainly cannot make a sweeping recommendation that all patients with high BP (or normal BP) should undergo 24-hour ambulatory BP monitoring, we think that the presence of inappropriate target organ disease such as LV hypertrophy or microalburminuria should raise suspicion of masked hypertension and motivate physicians to initiate a further work-up.
As to the therapeutic approach, we should remember that white-coat hypertension has a benign prognosis and can only be over-treated; therefore, a conservative approach is probably justified. Quite in contrast, masked hypertension has a much more serious prognosis and can only be undertreated; it deserves, therefore, a much more aggressive therapeutic approach.
For more information:
Clement D. N Engl J Med. 2003;348:2407-2415.
Hansen T. Hypertension. 2005;45:499-504.
Messerli F. J Am Coll Cardiol. 2002;40:2201-2203.
Ohkubo T. J Am Coll Cardiol. 2005;46:508-515. The sixth report of the Joint National Committee on prevention, detection, evaluation, and treatment of High blood pressure. Arch Intern Med. 1997;157:2413-2446.