A Timely Update on Ambulatory Blood Pressure Monitoring
From the get-go, it struck me that a series of blood pressures measured throughout the day and night would be more valuable than a random snapshot taken in my exam room. Additional evidence seemed to support my intuition. Nocturnal blood pressures (obtained by 24-hour readings) are “strongly associated” with heart disease.1 If we study a cohort of patients with similar office blood pressure readings, further augmented by data from ambulatory measurements, those with higher ambulatory values in the same cohort sustain greater target organ damage (left ventricular hypertrophy for example).1
That said, financial reimbursement for measurements of ambulatory blood pressures in the United States (not in the United Kingdom) are still a significant problem1—despite notable consensus for offering ambulatory blood pressure monitoring (ABPM) as a cost-effective technique to all people suspected of having hypertension.2 Many position papers have deliberated the medical and financial value of ABPM in identifying people at increased risk of developing hypertension, including this timely “Top Paper,”1 which looks at data and future directions of what seems to be an important addition to the diagnosis and treatment of hypertension.
Point A: What do ambulatory readings add to a hypertensive patient’s profile?
During sleep, blood pressure should normally “dip” approximately 10% to 20%. So-called “nondippers,” that is those individuals who do not experience that drop in blood pressure, are victims of increased cardiovascular morbidity and mortality. This prognostic information cannot be obtained with office readings.
Office and ambulatory blood pressures were recorded for 1000 patients. Ambulatory values were an independent prognostic risk factor. The same clinical research group also demonstrated that these ambulatory “hypertensives” incurred serious target organ injury from their “hidden” hypertension. Regarding one troublesome target organ complication—left ventricular hypertrophy—ambulatory blood pressures better predicted regression with treatment than office readings.
Other significant findings include:
• Fifteen to 30% of “white-coat hypertensives” (elevated blood pressures in the office/below target outside the office) are correctly identified as not being hypertensive and spared unnecessary therapy only by ambulatory readings.
• Some patients with resistant hypertension (failure to control on an appropriate 3-drug antihypertensive combination including a diuretic) are not genuinely “resistant” when monitored by ambulatory values.
• Masked hypertensives” (those individuals with normal office blood pressures, but elevated values otherwise) have the same risk of left ventricular hypertrophy and carotid plaque disease as bona fide hypertensives. These individuals can only be identified and appropriately treated after ambulatory monitoring.
“But” is the magic word!
The only reimbursable indication for ambulatory blood pressure readings from Medicare’s perspective is “suspected white coat hypertension.”1 Indications from other carriers are variable. Data is needed to prove that an “ounce of prevention” is the way to go with ABPM. More reimbursable indications may materialize when end organ complications are decreased by data unavailable from office readings, obtained only from ambulatory readings.
The future of ABPM in the United States is likely to change in the future so stay tuned! ■
Gregory W. Rutecki, MD, is a physician at the National Consult Service at the Cleveland Clinic. He is also a member of the editorial board of Consultant. Dr Rutecki reports that he has no relevant financial relationships to disclose.
References:
1. Turner JR, Viera AJ, Shimbo D. Ambulatory blood pressure monitoring in clinical practice: a review. Am J Med. 2015;128(1):14-20.
2. National Institute for Health and Clinical
Excellence. Hypertension: the clinical management of primary hypertension in adults. Clinical Guideline 127. 2011. www.nice.org.uk/guidance/CG127. Accessed February 2015.