Hypertension

Hypertension affects approximately 75 million adults in the United States and is a major risk factor for stroke, myocardial infarction, vascular disease, and chronic kidney disease.

Essential update: Increased long-term stroke risk in hypertensive patients with retinopathy

In a recent report of 2907 adults with hypertension participating in the Atherosclerosis Risk in Communities (ARIC) study, hypertensive retinopathy was associated with an increased long-term risk of stroke, independent of vascular risk factors.

Of the 2907 patients, 1406 (48.4%) had no retinopathy, 1354 (46.6%) had mild retinopathy, and 146 (5.0%) had moderate retinopathy. The one patient with severe hypertensive retinopathy was included in the moderate hypertensive retinopathy group (5.1%). After an average follow-up of 13 years, there were 165 incident strokes, including 146 cerebral infarctions. Increasing severity of hypertensive retinopathy was associated with an increased risk of stroke. The stroke risk was 1.35 (95% confidence interval, 0.96-1.89) in the mild retinopathy group and 2.37 (1.39-4.02) in the moderate/severe group. Corresponding figures for cerebral infarction were 1.52 (1.06-2.19) and 2.01 (1.10-3.70).

Signs and symptoms

Hypertension is defined as a systolic blood pressure (SBP) of 140 mm Hg or more, or a diastolic blood pressure (DBP) of 90 mm Hg or more, or taking antihypertensive medication

Based on recommendations of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7), the classification of BP for adults aged 18 years or older is as follows

• Normal: Systolic lower than 120 mm Hg, diastolic lower than 80 mm Hg
• Prehypertension: Systolic 120-139 mm Hg, diastolic 80-89 mm Hg
• Stage 1: Systolic 140-159 mm Hg, diastolic 90-99 mm Hg
• Stage 2: Systolic 160 mm Hg or greater, diastolic 100 mm Hg or greater

Hypertension may be primary, which may develop as a result of environmental or genetic causes, or secondary, which has multiple etiologies, including renal, vascular, and endocrine causes. Primary or essential hypertension accounts for 90-95% of adult cases, and secondary hypertension accounts for 2-10% of cases.

Diagnosis

The evaluation of hypertension involves accurately measuring the patient’s blood pressure, performing a focused medical history and physical examination, and obtaining results of routine laboratory studies A 12-lead electrocardiogram should also be obtained. These steps can help determine the following

• Presence of end-organ disease
• Possible causes of hypertension
• Cardiovascular risk factors
• Baseline values for judging biochemical effects of therapy

Other studies may be obtained on the basis of clinical findings or in individuals with suspected secondary hypertension and/or evidence of target-organ disease, such as CBC, chest radiograph, uric acid, and urine microalbumin.

Management

Many guidelines exist for the management of hypertension. Most groups, including the JNC, the American Diabetes Associate (ADA), and the American Heart Association/American Stroke Association (AHA/ASA) recommend lifestyle modification as the first step in managing hypertension.

Lifestyle modifications

JNC7 recommendations to lower BP and decrease cardiovascular disease risk include the following, with greater results achieved when 2 or more lifestyle modifications are combined

• Weight loss (range of approximate systolic BP reduction [SBP], 5-20 mm Hg per 10 kg)
• Limit alcohol intake to no more than 1 oz (30 mL) of ethanol per day for men or 0.5 oz (15 mL) of ethanol per day for women and people of lighter weight (range of approximate SBP reduction, 2-4 mm Hg)
• Reduce sodium intake to no more than 100 mmol/day (2.4 g sodium or 6 g sodium chloride; range of approximate SBP reduction, 2-8 mm Hg)
• Maintain adequate intake of dietary potassium (approximately 90 mmol/day)
• Maintain adequate intake of dietary calcium and magnesium for general health
• Stop smoking and reduce intake of dietary saturated fat and cholesterol for overall cardiovascular health
• Engage in aerobic exercise at least 30 minutes daily for most days (range of approximate SBP reduction, 4-9 mm Hg)

The AHA/ASA recommends a diet that is low in sodium, is high in potassium, and promotes the consumption of fruits, vegetables, and low-fat dairy products for reducing BP and lowering the risk of stroke. Other recommendations include increasing physical activity (30 minutes or more of moderate intensity activity on a daily basis) and losing weight (for overweight and obese persons).

The 2013 European Society of Hypertension (ESH) and the European Society of Cardiology (ESC) guidelines recommend a low-sodium diet (limited to 5 to 6 g per day) as well as reducing body-mass index (BMI) to 25 kg/m² and waist circumference (to < 102 cm in men and < 88 cm in women).

Pharmacologic therapy

If lifestyle modifications are insufficient to achieve the goal BP, there are several drug options for treating and managing hypertension. Thiazide diuretics are the preferred agents in the absence of compelling indications.

Compelling indications may include high-risk conditions such as heart failure, ischemic heart disease, chronic kidney disease, and recurrent stroke, or those conditions commonly associated with hypertension, including diabetes and high coronary disease risk. Drug intolerability or contraindications may also be factors. An angiotensin-converting enzyme (ACE) inhibitor, angiotensin receptor blocker (ARB), calcium channel blocker (CCB), and beta-blocker are all acceptable alternative agents in such compelling cases.

The following are drug class recommendations for compelling indications based on various clinical trials

• Heart failure: Diuretic, beta-blocker, ACE inhibitor, ARB, aldosterone antagonist
• Postmyocardial infarction: Beta-blocker, ACE inhibitor, aldosterone antagonist
• High coronary disease risk: Diuretic, beta-blocker, ACE inhibitor, CCB
• Diabetes: Diuretic, beta-blocker, ACE inhibitor, ARB, CCB
• Chronic kidney disease: ACE inhibitor, ARB
• Recurrent stroke prevention: Diuretic, ACE inhibitor