A Leading Role or Walk-on for Ambulatory BP Monitoring?

Q: Under what circumstances is 24-hour ambulatoryblood pressure monitoring (ABPM) appropriate?A: ABPM is especially helpful in the following settings:Suspected "white coat" hypertension in patientswith stage 1 hypertension and no evidence of targetorgan damage. More than 20% to 25% of adults mayexperience blood pressure (BP) readings in the clinic oroffice setting that are significantly higher than out-of-officereadings. Suspect white coat hypertension in a patientwith significant BP elevations in the office who has no evidenceof target organ damage on initial evaluation. A historyof normal BP readings outside the office can confirmthe diagnosis.A diagnosis of white coat hypertension can also beestablished by having the patient self-monitor BP at homeover a period of 2 to 3 weeks using an inexpensive automatedoscillometric device. These devices can also facilitatelong-term out-of-office monitoring of BP.Apparent drug resistance. Among the many possiblecauses of resistant hypertension are inappropriatedosing and/or timing of antihypertensive medications.There is a normal diurnal variation in BP over a 24-hourperiod, and some antihypertensive agents--particularly atlower dosages--may not provide optimal control for theentire period. Depending on the timing, BP may be elevatedwhen measured in the office but lower at other timesof the day. ABPM may help you establish the appropriatedosing and timing of antihypertensive medications.Hypotensive symptoms with antihypertensive medications.Patients are asked to maintain a log in which theylist symptoms and the times that they occur. These can becorrelated with BP at or closest to those times. Hypotensivesymptoms may or may not be related to the timing ofmedications. This diagnosis can be particularly difficult toestablish in patients who also have an element of whitecoat hypertension, because aggressive treatment of officeBP may result in hypotensive symptoms.ABPM also allows evaluation of nocturnal BP, whichtends to be lower than daytime BP. Evidence suggests thatdifferentiating "dippers" from "nondippers" with ABPMmay allow earlier identification of patients at increased riskfor target organ damage.¹Episodic hypertension. Documentation of episodicincreases in BP can be very difficult without ABPM. Inthis setting, the patient's logging of signs or symptoms at the time of a hypertensive episode can be extremely helpfulin establishing a diagnosis. Episodic increases in BPcan occur during stress or anxiety, but such increases mayalso result from conditions such as pheochromocytoma.Autonomic dysfunction. Patients with autonomic disorders, such as Shy-Drager syndrome, can experienceepisodes of sudden hypotension associated with lightheadednessor syncope. ABPM measurements of BP andheart rate during these episodes can be especially helpfulin making a presumptive diagnosis.A final caveat: cost considerations. ABPM can becostly for the patient because most insurance carriers donot routinely reimburse for this procedure, except for specificdiagnoses, such as refractory hypertension. Evenfor patients with this condition, however, insurance coverageis not universal.Recently, Medicare started to reimburse for ABPM.However, in addition to being limited to Medicare-eligiblepersons, this coverage is restricted to a very small groupof patients with labile and/or white coat hypertension whoare not taking antihypertensive medications. For a patientto be eligible for reimbursement, the medical record mustinclude documentation of hypertensive BP readings onseveral occasions in the office together with documentednormal readings on multiple occasions outside the office.If you have considered the purchase of ABPM equipmentfor your practice, keep in mind that each monitorcosts several thousand dollars, besides the cost of the computerprogram for analysis and printing of reports. Aninexpensive alternative is to have patients purchase an oscillometricdevice for home use. With periodic calibrationin the office, these devices have a prolonged life and arequite reliable. In addition to helping distinguish sustainedfrom white coat hypertension and assessing a responseto therapy, home monitoring may improve adherence totreatment and reduce the cost of care.

References:

REFERENCE:

1.

Cuspidi C, Macca G, Sampiere L, et al. Target organ damage and non-dippingpattern defined by two sessions of ambulatory blood pressure monitoring in recentlydiagnosed essential hypertensive patients.

J Hypertens

. 2001;19:1539-1545

FOR MORE INFORMATION:

• McAlister FA, Straus SE. Evidence-based treatment of hypertension. Measurementof blood pressure: an evidence-based review. BMJ. 2001;322:908-911.
• Pickering TG, for an American Society of Hypertension Ad Hoc panel. Recommendationsfor the use of home (self) and ambulatory blood pressure monitoring.Am J Hypertens. 1996;9:1-11.

• Staessen JA, Byttebier G, Buntinx F, et al. Antihypertensive treatment based onconvention or ambulatory blood pressure measurement. A randomized controlledtrial. Ambulatory Blood Pressure Monitoring and Treatment of Hypertension Investigators.JAMA. 1997;278:1065-1072.