Hypertension

Hypertension continues to be one of the most prevalent and treatable components of the cardiometabolic syndrome. A recent review of the National Health and Nutrition Examination Survey (NHANES) suggests that an estimated 58.4 million Americans have high blood pressure requiring therapy1. Worldwide, the prevalence of hypertension has been estimated to be as high as 1 billion people with 7.1 million deaths per year related to its complications2. In the US, hypertension continues to be underdiagnosed and under-treated with approximately 30% of patients remaining unaware of their hypertension, 40% of patients not receiving any treatment, and another two-thirds with blood pressure above 140/903. The prevalence of hypertension increases with age with approximately 75% of patients aged 70 or older demonstrating high blood pressure4. The recent Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure

Table 7.1 Cardiometabolic risk factors

Hypertension Abdominal adiposity Low HDL cholesterol High LDL cholesterol Hypertriglyceridemia

Impaired glucose tolerance, impaired fasting glucose, insulin resistance, and diabetes Metabolic syndrome Smoking

Inflammatory markers including C-reactive protein

Table 7.2 Classification of blood pressure reference 3, with permission

in adults. From

BP classification

SBP (mmHg)

DBP (mmHg)

Normal

< 120

and < 80

Prehypertension

120-139

or 80-89

Stage 1 hypertension

140-159

or 90-99

Stage 2 hypertension

a 160

or a 100

Table 7.3 Cardiovascular complications of hypertension Coronary artery disease

Left ventricular systolic dysfunction leading to congestive heart failure

Left ventricular diastolic dysfunction leading to congestive heart failure Left ventricular hypertrophy Atrial fibrillation Cerebrovascular disease Peripheral arterial disease

BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure

BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure

Table 7.3 Cardiovascular complications of hypertension Coronary artery disease

Left ventricular systolic dysfunction leading to congestive heart failure

Left ventricular diastolic dysfunction leading to congestive heart failure Left ventricular hypertrophy Atrial fibrillation Cerebrovascular disease Peripheral arterial disease

(JNC VII) proposed new definitions for hypertension and prehypertension (Table 7.2)3.

Because of its increasing prevalence and wide-reaching effects on morbidity and mortality, hypertension continues to be a crucial target in cardiovascular risk reduction. Many consider hypertension to be the dominant risk factor for premature onset cardiovascular disease because it is more common than smoking, dyslipidemia, and diabetes5. The cardiovascular complications of hypertension include coronary artery disease, left ventricular systolic and diastolic dysfunction leading to congestive heart failure, left ventricular hypertrophy, atrial fibrillation, cerebrovascular disease, and peripheral arterial disease (Table 7.3). The World Health Organization has suggested that poorly controlled blood pressure may be responsible for up to 62% of cerebrovascular disease and 49% of coronary artery disease3. The Framingham Heart Study has demonstrated that the first manifestations of the cardiovascular complications of hypertension tend to be coronary artery disease in men and stroke in women6. The risk of cardiovascular events has been shown to increase according to the degree of hypertension, and this relationship appears to strengthen with advancing age7. A recent study revealed that both increasing severity of systolic and diastolic hypertension correlated with risk of all-cause and cardiovascular mortality regardless of patient age, although a J-shaped curve was suggested for diastolic blood pressure at advanced ages (Figure 7.1)8. Data from observational studies have demonstrated a linear relationship between risk of death from both ischemic heart disease and stroke and increasing levels of systolic and diastolic blood pressure in all age groups ranging from 40 to 89 years old (Figures 7.2 and 7.3)9. Before JNC VII, patients with 'prehypertension' or blood pressures ranging from 120 to 139mmHg systolic and/or 80 to 89mmHg diastolic were not widely recognized as a population at increased risk for cardiovascular events. However, long-term follow-up data from the Framing-ham Heart Study have demonstrated a two-fold increase in the relative risk of cardiovascular events among patients with blood pressures of 130-139/ 85-89 mmHg (Figure 7.4)10.

In addition to these cardiovascular complications, hypertension is also an important cause of chronic kidney disease (Figures 7.5 and 7.6) and may be a predisposing factor in the development of type 2 diabetes mellitus. One study demonstrated that patients with hypertension were nearly 2.5 times more likely to develop type 2 diabetes than those without hypertension12. In the Heart Outcomes Prevention Evaluation (HOPE) study, patients at high risk for cardiovascular events receiving the antihypertensive ramipril (an angiotensin-converting enzyme inhibitor) had a significant reduction in the relative risk of developing diabetes compared with those receiving placebo13. It remains unclear whether hypertension itself is a risk factor for the development of diabetes or if it is associated with other factors such as obesity that may contribute to insulin resistance and diabetes. Furthermore, the reduction in the diagnosis of new diabetes among patients receiving ramipril in the HOPE study may be related to intrinsic properties of the medication itself rather than its blood pressure-lowering effects, as other antihyper-tensives have not been shown to reduce the incidence of diabetes. Frequently coexistent, hypertension and diabetes in combination have a particularly potent effect on the risk of cardiovascular disease. In the Systolic Hypertension in the Elderly Program (SHEP)

Figure 7.1 Risk surfaces for all-cause and cardiovascular mortality as a function of systolic and diastolic blood pressure by age groups of <65 or > 65 years old. The surfaces demonstrate the relative risk for all-cause and cardiovascular mortality for combinations of systolic and diastolic blood pressure. From reference 8, with permission

Figure 7.1 Risk surfaces for all-cause and cardiovascular mortality as a function of systolic and diastolic blood pressure by age groups of <65 or > 65 years old. The surfaces demonstrate the relative risk for all-cause and cardiovascular mortality for combinations of systolic and diastolic blood pressure. From reference 8, with permission study, hypertensive patients with diabetes receiving blood pressure-lowering therapy with low-dose diuretics demonstrated twice the absolute risk reduction in cardiovascular events compared with hypertensive patients without diabetes14. In the Systolic Hypertension in Europe (Syst Eur) Trial, the same degree of blood pressure-lowering was associated with a 76% risk reduction in cardiovascular mortality among diabetic patients receiving antihypertensive therapy compared with a 13% reduction among non-diabetic patients15. These studies suggest that patients with diabetes and hypertension are at a significantly increased risk of cardiovascular events compared with non-diabetics with hypertension and that aggressive antihypertensive therapy should be pursued in these high-risk patients. Even prehypertensive patients with diabetes demonstrate a significantly higher risk of cardiovascular events compared with non-diabetic prehypertensive patients16.

A growing body of evidence has established hypertension as one of the most important modifiable risk factors for cardiovascular disease and an integral component of the cardiometabolic syndrome. Hypertension significantly augments the risk of cardiovascular

Figure 7.2 Ischemic heart disease mortality rate in each decade of age versus usual systolic (a) and diastolic (b) blood pressure at the start of that decade. From reference 9, with permission

events when combined with other cardiometabolic risk factors such as diabetes.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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