Low BP associated with increased risk for stroke and heart attack
Researchers found a J-curve relationship between cardiovascular events and blood pressure (BP) at above and below reference levels.
Data results from the American Society of Hypertension 24th Annual Scientific Meeting and Exposition, San Francisco Marriott, San Francisco, CA, May 6 – Saturday, May 9, 2009, show that patients with coronary artery disease who also have low blood pressure are at higher risk for stroke and heart attack.
Researchers examining results from the TNT study analyzed 10,001 patients with coronary artery disease. Patients were assigned to either 10 mg of atorvastatin daily (n=5,006) or 80 mg atorvastatin daily (n=4,995). The primary endpoint was a composite of death from coronary disease, nonfatal MI (heart attack), resuscitation following cardiac arrest and fatal or nonfatal stroke.
Among the 10,001 patients, 982 (9.82%) reached the primary endpoint during the 4.9 follow-up period.
The researchers reported a J-shaped curve relationship between systolic or diastolic BPs both above and below reference BP ranges (130 to 140 mm Hg for systolic, 70 to 80 mm Hg for diastolic) and major cardiovascular events, despite a reduction in LDL levels.
According to the study results, there was a 3.1-fold increase in the risk for major cardiovascular events in patients with a systolic BP of 110 mm Hg and a 3.3-fold increased risk in the group with a diastolic BP of 60 mm Hg.
Following application of a nonlinear Cox model, the lowest event rates were associated with a systolic BP of 140.6 mm Hg and diastolic BP of 79.8 mm Hg for diastolic BP.
Franz Messerli, MD, director of the hypertension program at Saint Luke’s-Roosevelt Hospital in New York, said in an interview:
“There is no question that a lot of patients are not controlled at present, but the dictum that lower is better is not true in all patients and particularly not true in patients with manifest coronary artery disease . . . In patients with coronary artery disease, you really have to be careful.”This means that the current 'healthy' guidelines on BP - the 'optimal' level of 120/80 may need rethinking.