Low Blood pressure Could Lead to Increased Risk of Heart Attack and Stroke

A new study warns that low blood pressure (BP) levels may actually increase cardiovascular risk among patients with heart disease.

Researchers at St. Luke's-Roosevelt Hospital (New York, NY, USA) analyzed data from the Treating to New Targets (TNT) trial of atorvastatin, which involved a total of 10,001 patients with coronary artery disease (CAD), who received either 10 mg of atorvastatin (5,006 patients) or 80 mg of atorvastatin daily (4,995 patients). The primary composite endpoint was death from coronary disease, nonfatal myocardial infarction (MI), resuscitation after cardiac arrest, and fatal or nonfatal stroke.

The researchers found a relationship between systolic blood pressure (SBP), diastolic blood pressure (DBP), and major cardiovascular events that followed a J-curve pattern, with increased event rates above and below the reference BP ranges. A nonlinear Cox model identified a BP measurement of 140.6 mmHg for SBP and 79.8 mmHg for DBP where the event rate was lowest. The risk of a major cardiovascular event increased 3.1-fold in the group with SBP lower than 110 mmHg, and 3.3-fold in the group with DBP lower than 60 mmHg. A similar J-curve relationship was found for the secondary endpoints of all-cause mortality, cardiovascular mortality, nonfatal MI and nonfatal stroke. The researchers concluded, therefore, that despite substantial lowering of LDL-cholesterol, a relationship existed between both systolic and diastolic BP and the risk of future cardiovascular events, suggesting that low BP levels may actually be harmful among the study's high-risk population. The study was presented at the annual scientific meeting of the American Society of Hypertension (ASH), held during May 2009 in San Francisco (CA, USA).

"Our findings negate the dictum that with blood pressure, lower is always better," said coauthor Franz Messerli, M.D., director of the hypertension program at St. Luke's-Roosevelt Hospital. "As we learn more about the effect of blood pressure on cardiovascular risk, we continually refine our understanding of the optimal treatment and blood pressure targets for these patients."

Atorvastatin, commonly known as Lipitor (a product of Pfizer), is the largest-selling drug globally, and is primarily used for lowering blood cholesterol. A member of the statin family, Atorvastatin works by inhibiting HMG-CoA reductase, the rate-determining enzyme located in hepatic tissue that produces mevalonate, a small molecule used in the synthesis of cholesterol and other derivatives. This lowers the amount of cholesterol produced, which in turn lowers the total amount of LDL cholesterol.

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