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Hypertension in the elderly
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On April 25, the American College of Cardiology and American Heart Association, in collaboration with the American Academy of Neurology, Association of Black Cardiologists, American Geriatrics Society, American Society of Hypertension, American Society of Nephrology, American Society for Preventive Cardiology, and the European Society of Hypertension, released an Expert Consensus Document on Hypertension in the Elderly. I had the opportunity to co-chair the writing committee for this effort and because of the importance of this topic, I will use this column to summarize the areas that I believe are important for your practice.
With aging, there is a dramatic increase in the prevalence of hypertension, so that by age 70 years, most people have hypertension. This elderly age group is the most rapidly growing segment of our population, and the magnitude of this problem is not generally appreciated. Recall that in the Framingham Heart Study, hypertension eventually developed in more than 90% of participants with a normal BP at age 55 years. By 60 years of age, approximately 60% of the population has hypertension; by 70 years, about 65% of men and about 75% of women have hypertension. Census bureau data and projections reveal that women older than the age of 65 years will comprise more than 20% of the population by 2030. Hypertension is most prevalent among older African-American women.
Identifying characteristics
In older adults, hypertension is characterized by an elevated systolic BP with normal or low diastolic BP caused by age-associated stiffening of the large arteries. This change in structure of conduit arteries results in an increase in pulse wave velocity. So, reflected pressure waves summate with the forward pressure waves in the ascending aorta to increase the central systolic BP. Besides exposing the coronary and cerebral arteries to this high pressure, this process also increases left ventricular wall stress and myocardial oxygen requirements to worsen ischemia, which is often present in elderly patients. Additionally, the reflected blood flow waves subtract from the forward blood flow wave (ie, the stroke volume) to reduce cardiac output and, ultimately, organ blood flow. The latter is particularly deleterious for the coronary, cerebral and renal circulations.
These changes have important consequences in the elderly patient. Hypertension is a potent risk factor for CVD in the elderly. Most of the patients with incident MI, HF and stroke have a history of prior hypertension. Data from observational studies indicate that death from ischemic heart disease and stroke increases progressively and log-linearly from BP levels as low as 115 mm Hg systolic and 75 mm Hg diastolic upward. For every 20 mm Hg systolic or 10 mm Hg diastolic increase in BP, there is a doubling of mortality from both ischemic heart disease and stroke. These increased risks persist into at least the ninth decade of life.
Treatment
Numerous randomized trials have shown substantial reductions in CV outcomes in cohorts of patients aged 60 to 79 years with antihypertensive drug therapy, and the magnitude of response appears similar to that observed in younger cohorts. The effect on all-cause mortality has been modest, but in the HYVET study (treatment of hypertension in patients 80 years of age or older), antihypertensive therapy reduced all-cause mortality by more than 20% in those aged at least 80 years.
Although increases in the treatment and control of BP among older hypertensive adults have occurred in recent years, BP control rates remain suboptimal in the elderly. Data from the 2005-2006 National Health and Nutritional Examination Survey indicate that for individuals older than 60 years, BP control rates are less than 50%.
For older adults, the Consensus Document recommends that nonpharmacologic lifestyle measures should be strongly encouraged to retard the development of hypertension and as adjunctive therapy in those with established hypertension. However, most elderly hypertensive patients will require additional therapy with multiple antihypertensive drugs to reduce their BP.
Although the specific BP at which antihypertensive therapy should be initiated in the elderly is unclear, a threshold of 140 mm Hg/90 mm Hg in those aged 65 to 79 years and a threshold systolic BP of 150 mm Hg in people aged 80 years and older is reasonable until more data become available. Although the optimal BP treatment goal in the elderly has not been determined, a therapeutic target of less than 140 mm Hg/90 mm Hg in those aged 65 to 79 years was endorsed and a systolic BP of 140 mm Hg to 145 mm Hg, if tolerated, in those aged at least 80 years was considered reasonable.
Diuretics, ACE inhibitors, angiotensin receptor antagonists, calcium antagonists and beta-blockers have all shown benefit on CV outcomes in randomized trials among elderly cohorts. So the choice of specific agents is dictated by efficacy, tolerability, presence of specific comorbidities and cost. The Expert Consensus Document on Hypertension in the Elderly notes that absorption and distribution of antihypertensive drugs are unpredictable in the elderly. The half-life of most antihypertensive drugs is increased in the elderly. So, initiation of all of these drugs in the elderly should generally be at the lowest dose with gradual increments as tolerated.
The Expert Consensus Document on Hypertension in the Elderly also emphasizes that the high prevalence of CV and non-CV comorbidities among the elderly dictates a need for great vigilance if one is to avoid treatment-related side effects. Orthostatic hypotension is a particularly prevalent manifestation of the autonomic dysregulation observed in elderly hypertensive patients, and this side effect is not only lifestyle limiting but also associated with increased events.
Conclusion
In summary, hypertension is highly prevalent among the elderly and is a major, treatable risk factor for CV disease. Typically, elderly patients have systolic BP elevation with low diastolic BP (due to “stiff arteries”). Their many comorbidities make management very challenging, but the evidence gathered supports the benefits that can accrue with BP lowering among the elderly. Lifestyle modification is very helpful, even when added to drug therapy. Remember to begin with low drug doses and titrate slowly. For those aged at least 80 years, 140 mm Hg to 145 mm Hg is an acceptable systolic BP goal if tolerated.
Carl J. Pepine, MD, is Professor of Medicine, Division of Cardiovascular Medicine at the University of Florida, Gainesville. He is also Chief Medical Editor of Cardiology Today.
For more information:
- Aronow W. J Am Coll Cardiol. 2011;57:2037-2114.
- Beckett N. N Engl J Med. 2008;358:1887-1898.