How Low Do We Go? Update on Hypertension

Transcription

1 How Low Do We Go? Update on Beth L. Abramson, MD, FRCPC, FACC As presented at the University of Toronto s Saturday at the University Session (September 2003) Arecent World Health Organization report states hypertension is a leading risk for death worldwide, in both developed and developing nations. Long-term studies show an increasing death rate in patients with increasing systolic and diastolic blood pressure (BP). Hypertensive heart disease, as manifested by left ventricular hypertrophy (LVH) on electrocardiography (ECG), is also associated with higher death rates in men and women. Cardiovascular (CV) disease is the leading cause of death in Canadian men and women. Recent studies show a negative impact of high to normal BP and an increased risk of CV disease in the general population. These phenomena have led to newer, broader, and more aggressive guidelines about the diagnosis and treatment of hypertension. Otherwise healthy people with a BP < 130/85 mmhg have a higher long-term chance of CV events than those with optimal BP < 120/70 mmhg. American guidelines now include a prehypertension stage (systolic BP 120 mmhg to 139 mmhg, and diastolic BP 80 mmhg to 89 mmhg) which should be addressed by lifestyle changes. In the U.S., as in Canada, there is poor awareness, treatment, and control of hypertension. In Canada, over 20% of the population between 18 to 70, and half of Canadians over The Canadian Journal of Diagnosis / February

2 Gail s case Gail, 67, comes to your office for a general checkup. Functionally, she has no complaints. She has a history of fibroids and osteoarthritis. Results of the physical exam show: Heart rate: 74 beats/ minute Blood pressure: 162/84 mmhg (elevated) Waist circumference: 110 cm No bruits on vascular exam Peripheral pulses: Palpable Heart sounds: Normal What is your approach to this patient? Are further tests required? Should you treat the elevated blood pressure and, if so, with what? For a followup on Gail, go to page 93. Table 1 Additional tests 1. Urinalysis 2. Complete blood count 3. Blood chemistry (potassium, sodium, creatinine) 4. Fasting glucose 5. Fasting total cholesterol, HDL-C, LDL-C, and TG 6. Standard 12-lead ECG HDL-C: High-density lipoprotein cholesterol LDL-C: Low-density lipoprotein cholesterol TG: Triglycerides ECG: Electrocardiogram Dr. Abramson is an assistant professor of medicine, University of Toronto, and director, cardiac prevention centre, division of cardiology, St. Michael s Hospital, Toronto, Ontario. Frequently Asked Questions 1. Should an echocardiogram be performed? Routine assessment with echocardiography is not recommended, as it is unlikely to change your management. However, in certain cases, where assessment of left ventricular dysfunction or hypertrophy is suspected, it may influence management. 2. Which class of drug should I use? In general, for a patient with no comorbidity, use whatever works. Most large trials have not found a significant overall advantage of one class of drug over another in the general hypertensive population. 3. Do I have to look for unusual conditions if my patient isn t controlled after switching classes of drugs? No. Although blood pressure control is achievable, recent studies suggest most patients need more than one drug to achieve this. Instead of switching classes, try adding medication to the patient s prescription. 4. What can I do to increase patient compliance? Patient education may help. Having a patient take a stroke-prevention pill rather than a blood pressure pill may be part of the answer. 90 The Canadian Journal of Diagnosis / February 2004

3 65 have hypertension. The challenge in Canada is effective diagnosis and treatment. How is hypertension diagnosed? The first step in the diagnosis is a proper assessment. The Canadian Education Program recommends going back to basics as a good technique. The patient should rest for five minutes, and use of an appropriate cuff size is necessary. The program recommends a mercury manometer, a recently calibrated aneroid, or a validated electronic device. To exclude the possibility of auscultatory gap, cuff pressure should be increased rapidly to 30 mmhg above the level of disappearance of radial pulse, and the pressure dropped by 2 mmhg/beat. It is recommended to take two BP measurements, one minute apart. If the BP is very high (> 180/105 mmhg), or if there is target organ damage, treatment should be started after three visits. In all patients with hypertension, additional tests need to be ordered to evaluate and treat other aspects of CV disease (Table 1). What is the threshold for initial treatment? After the diagnosis is made, the issue of when to treat and addressing how low to go is important. Current Canadian guidelines have been simplified, and are listed in Table 2. In cases of isolated systolic hypertension, current recommendations are to treat if the systolic BP is > 160 mmhg, and to aim for a target BP of < 140 mmhg. How do lifestyle changes help? Although it s often easier to take a pill than to make a lifestyle change, all medications should be given with dietary counselling. Exercise should also be encouraged (Table 3). Salt restriction has come into favour again, with the validation of the Dietary Approaches to Stop (DASH) diet. The Canadian Journal of Diagnosis / February

4 Table 2 Threshold for initiation of treatment and target values Initiation Target Condition (SBP/DBP mm/hg) (SBP/DBP mm/hg) Diastolic±systolic 140/90 < 140/90 hypertension Isolated systolic hypertension SBP > 160 < 140 Home BP measurement 135/85 < 135/85 (no diabetes, renal disease, or proteinuria) Diabetes 130/80 < 130/80 Renal disease 130/80 < 130/80 Proteinuria 125/75 < 125/75 SBP: Systolic blood pressure DBP: Diastolic blood pressure BP: Blood pressure What are the treatment options? Current Canadian recommendations suggest individualizing treatment if there are associated risk factors or concomitant diseases or conditions. For example, if a patient has had a recent myocardial infarction (MI), a beta blocker is a good choice. Obviously, this would not be the case if the patient had asthma. In general, for a patient with hypertension and no comorbid conditions, physicians should prescribe whatever works, but should also remember to tackle two problems with one drug whenever possible. Most large trials have not found a significant overall advantage of one class of drugs over another in the general hypertensive population, despite ongoing academic debate. What do the trials show? There may be specific circumstances where one class of drug may show more benefit. In Table 3 Impact of lifestyle therapies on blood pressure Intervention Targeted change SBP/DBP reduction Sodium reduction 100 mmol/day -5.8/-2.5 Weight loss -4.5 kg -7.2/-5.9 Alcohol reduction -2.7 drink/day -4.6/-2.3 Exercise 3 times/week -10.3/-7.5 Dietary patterns DASH diet 11.4/-5.5 DASH: Dietary Approaches to Stop SBP: Systolic blood pressure DBP: Diastolic blood pressure Table 4 Drug combinations Column 1 Thiazide diuretic Long-acting dihydropyridine calcium channel blocker For additive hypotensive effect in dual therapy, combine an agent from Column 1 with any in Column 2. ACE: Angiotensin-converting enzyme ARB: Angiotensin receptor blocker Column 2 Beta blocker ACE inhibitor ARB 92 The Canadian Journal of Diagnosis / February 2004

5 the recent Losartan Intervention For End point reduction in hypertension (LIFE) study, patients with LVH on the ECG benefited from angiotensin receptor blockers (ARB) over beta blockers. The current Canadian Guidelines reflect this and, essentially, include all classes of drugs as potential first-line therapy. The Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT) compared a calcium channel blocker, angiotensin-converting enzyme (ACE) inhibitor, and a diuretic in patients with hypertension. At the end of the day, there were no differences in long-term rates of death and MI in either group. One of the main messages of ALL- HAT, however, is that although BP control is Anti-inflammatory analgesic agent.product Monograph available upon request. General warnings for NSAIDs should be borne in mind. achievable (almost 80% of Canadians in the study achieved BP control), most patients needed more than one drug to achieve it. A diuretic is a good first choice in many patients with hypertension (while watching for hypokalemia and a tendency for impaired glucose tolerance in some patients). However, many patients will need an additional drug (Table 4). *TM G.D. Searle & Co., Pfizer Canada Inc., licensee. What s the bottom line? We are undertreating hypertension, despite the fact that treatment has a proven benefit in reducing stroke, congestive heart failure, MI, and death. D x References available contact The Canadian Journal of Diagnosis at diagnosis@sta.ca. Cont d on page 94 A followup on Gail On screening bloodwork, Gail was found to have subclinical diabetes. Her blood pressure was still high after five visits to your office, despite attempts at lifestyle changes. Her diabetes, however, was controlled with modest weight loss, and she is still thinking about exercise. A combination of angiotensin-converting enzyme inhibitor and diuretic managed to get her blood pressure down to 128/75 mmhg. Her lipids were also not at target (low-density lipoprotein cholesterol > 2.6 mmol/l), and she ended up on statin therapy, in addition to the recommended acetylsalicylic acid. Her risk for myocardial infarction and stroke has decreased significantly. She is also more compliant with taking her stroke-prevention pills after reading about her risk. The Canadian Journal of Diagnosis / February

6 Take-home message How can hypertension be treated? Lifestyle changes, such as exercise and diet, are crucial to treating hypertension. There are many drugs on the market, but patients with hypertension and no concomitant conditions should use whatever works for them. Sometimes a combination of drugs works best, but use only one drug if that s all it takes. Surf your way to The Heart and Stroke Foundation of Canada: 2. The Canadian Education Program: For an electronic version of this article, visit: The Canadian Journal of Diagnosis online.