The Concept of CMR

Hypertension and CVD

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Data on more than one million individuals has shown that death from both IHD and stroke increases progressively and linearly from BP levels as low as 115/75 mmHg (8). Beginning at 115/75 mmHg, every 20/10 mmHg increase in BP doubles the rate of mortality from both IHD and stroke (2). In addition, longitudinal observations from the Framingham Heart Study have shown that BP values from 130/85 to 139/89 mmHg increase CVD risk more than twofold when compared to BP levels below 120/80 mmHg (9). In addition, systolic BP has been reported to be a more important CVD risk factor than diastolic BP. Diastolic BP is a potent CVD risk factor until age 50, while systolic BP, which increases with age, is a major CVD risk factor throughout life (2).  

In the Framingham study, Wilson et al. (10) followed a cohort of 3,323 middle-aged adults for the onset of CVD, CHD, and type 2 diabetes over an 8 year period. They reported that hypertension and HDL cholesterol contributed most to CVD outcomes. In addition, elevated BP was found to enhance the risk of myocardial infraction (MI) in populations with severe hypercholesterolemia (11, 12).

Effect of anti-hypertensive therapy on CVD risk

Adopting a healthy lifestyle is crucial to prevent hypertension. However, anti-hypertensive therapy is recommended when BP is over 140/90 mmHg. Data from clinical trials has shown that anti-hypertensive therapy can have a beneficial effect, reducing stroke incidence by 35-40%, myocardial infarction by 20-25%, and heart failure by over 50% (13). In patients with hypertension from 140/90 to 159/99 mmHg and additional cardiovascular risk factors, a 12 mmHg reduction in systolic BP over 10 years will prevent 1 death for every 11 patients treated (2). For more information on anti-hypertensive therapy, please visit the Managing CMR section.

Reference

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2. Chobanian AV, Bakris GL, Black HR, et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2003; 42: 1206-52.

8. Lewington S, Clarke R, Qizilbash N, et al. Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies. Lancet 2002; 360: 1903-13.

9. Vasan RS, Larson MG, Leip EP, et al. Impact of high-normal blood pressure on the risk of cardiovascular disease. N Engl J Med 2001; 345: 1291-7.

10. Wilson PW, D'Agostino RB, Parise H, et al. Metabolic syndrome as a precursor of cardiovascular disease and type 2 diabetes mellitus. Circulation 2005; 112: 3066-72.

11. Kannel WB, Castelli WP and Gordon T. Cholesterol in the prediction of atherosclerotic disease. New perspectives based on the Framingham Study. Ann Intern Med 1979; 90: 85-91.

12. Salonen JT, Puska P and Kottke TE. Smoking, blood pressure and serum cholesterol as risk factors of acute myocardial infarction and death among men in Eastern Finland. Eur Heart J 1981; 2: 365-73.

13. Neal B, MacMahon S and Chapman N. Effects of ACE inhibitors, calcium antagonists, and other blood-pressure-lowering drugs: results of prospectively designed overviews of randomised trials. Blood Pressure Lowering Treatment Trialists' Collaboration. Lancet 2000; 356: 1955-64.

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