ORLANDO – Although higher systolic blood pressure and LDL cholesterol are traditional risk factors for cardiovascular disease, each may have a different effect on the cerebrovascular and coronary systems.
Pooled analysis of three landmark studies done on the cholesterol-lowering agent atorvastatin in high-risk patients showed that higher baseline systolic blood pressure is predictive of a significantly higher risk of stroke. Meanwhile, higher baseline LDL cholesterol is predictive of a significantly higher risk of coronary events, the analysis showed.
The findings have implications on both research design and clinical practice, Dr. Prakash C. Deedwania, the study’s lead author, said at the annual scientific sessions of the American Heart Association.
Patients who might be at risk of both stroke and coronary events should be treated aggressively to reduce systolic blood pressure and LDL cholesterol, he said.
Dr. Deedwania and his colleagues pooled data on 21,727 patients from three trials: Treating to New Targets (TNT), which compared 10 mg with 80 mg atorvastatin in patients with stable coronary heart disease and LDL levels below 130 mg/dL (N. Engl. J. Med. 2005;352:1425-35), Incremental Decrease in End Points Through Aggressive Lipid Lowering (IDEAL), which compared high-dose (80 mg) atorvastatin with normal-dose (20-40 mg) simvastatin in post-MI patients (JAMA 2005;294:2437-45), and the Collaborative Atorvastatin Diabetes Study (CARDS), which compared 20 mg atorvastatin with placebo in patients with type 2 diabetes and without established coronary heart disease (Lancet 2004;364:685-96).
Results showed that with each 10-mm Hg increase in baseline systolic blood pressure, the risk of a fatal or nonfatal stroke increased by 16%. Meanwhile, each 10-mg/dL increase in baseline LDL cholesterol increased the risk of coronary events by 5%. Both differences were significantly different.
Dr. Deedwania said that the reduction in LDL cholesterol has been associated with a decrease in the risk of stroke, "but perhaps by a different mechanism."
The authors also looked at a subgroup of patients with type 2 diabetes (5,408 patients from the three trials), and found results consistent with the larger cohort.
Although systolic blood pressure is known to be a powerful predictor of stroke, many clinicians may not be aware that LDL cholesterol is not associated with an increased risk of stroke, said Dr. Deedwania. "What predicts baseline risk is different than what happens in treatment, so there are yet many lessons to be learned from these trials."
Dr. Deedwania has received research grants from Pfizer. He has been a consultant to and on the advisory boards of Pfizer and Novartis.