SAN ANTONIO — Among patients with known cardiovascular disease there is no J-shaped association between blood pressure and either future cardiovascular events or all-cause mortality, according to data from the China National Hypertension Survey Epidemiology Study.
“These data indicate there is a strong, independent, and direct association between blood pressure and mortality among men and women with a history of cardiovascular disease. Furthermore, our findings support a lower blood pressure achievement goal among patients with cardiovascular disease in order to reduce mortality,” Dr. Jing Chen said at a meeting of the American Heart Association Council for High Blood Pressure Research.
The possible existence of a J-curve—that is, the notion that driving blood pressures lower is beneficial only to a certain point, after which mortality starts to climb again—has a lengthy history in the field of hypertension. The possibility that it existed in the general population was debated for many years until a consensus emerged that it does not, and that lower is better. More recently the J-curve has been resurrected, with some reports indicating it applies to patients with cardiovascular disease, explained Dr. Chen of Tulane University, New Orleans.
To examine this issue, she turned to the China National Hypertension Survey Epidemiology Study, which enrolled a nationally representative sample of 158,666 participants aged 15 years or older in 1991. The study included 2,251 men and 1,941 women with a baseline history of coronary heart disease or stroke.
At follow-up during 1999–2000, a direct association was seen between blood pressure and cardiovascular mortality in the subgroup having baseline cardiovascular disease—no J-shaped curve.
Compared with normotensive men with a history of cardiovascular disease, those with prehypertension as defined by Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC) VII had an 18% greater risk of cardiovascular death after adjustment for age, smoking, alcohol intake, diabetes, physical activity, body mass index, and geographic region. Prehypertensive women had a 21% increase in risk.
Men and women with stage 1 hypertension had risk increases of 24% and 62%. Cardiovascular mortality was increased by 71% in men with stage 2 hypertension and by 72% in stage 2 women.