For diabetic patients with hypertension and coronary artery disease (CAD), keeping systolic blood pressures below 130 mm Hg did not improve cardiovascular outcomes, according to the INVEST trial published July 7 in the Journal of the American Medical Association.
According to the authors, two out of three adults with diabetes are diagnosed with high blood pressure (greater than 140 mm Hg), which results in a 50 percent increased risk of cardiovascular events.
Rhonda M. Cooper-DeHoff, PharmD, and colleagues from the University of Florida in Gainesville, Fla., enrolled 6,400 patients into the INVEST (International Verapamil SR-Trandolapril) trial to see whether patients who could gain a blood pressure of less than 130 mm Hg (tightly-controlled) would have less cardiovascular events than those with a blood pressure range between 130 mm Hg to less than 140 mm Hg (usual control).
The trial took place at 862 sites between September 1997 and December 2000.
All patients were diabetics, at least 50 years old and had CAD. Patients received either a calcium antagonist, beta blocker followed by angiotensin-converting enzyme inhibitor and a diuretic or both to help control blood pressure. Patients also received therapy to reach systolic blood pressure of less than 130 mm Hg (systolic) and less than 85 mm Hg (diastolic) in the tightly controlled group.
The researchers categorized patients into three groups: Tight control if systolic blood pressure of at less than 130 mm Hg was maintained; usual control if it ranged from 130 mm Hg to less than 140 mm Hg; and uncontrolled if it was 140 mm Hg or higher.
During the trial, researchers looked at all-cause mortality as the primary outcome including nonfatal MI or nonfatal stroke.
Results showed that a total of 286 patients in the tightly controlled group died during the study compared to 249 who died in the usual control group and 431 in the uncontrolled group.
Surprisingly, researchers found that overall all-cause mortality was greater in the more tightly controlled group than the usual control group, 22.8 percent versus 21.8 percent, respectively.
"Optimum systolic blood pressure levels should be between 130 and 140 for patients coping with the diabetes-heart disease combination," said Cooper-DeHoff.
While blood pressure levels of 120 mm Hg or lower may be optimal for healthy patients, Cooper-DeHoff said that these levels for diabetics with CAD may actually increase the risk of MI, stroke and mortality.
“While lowering blood pressure to less than 140 is very important, based on our data and data recently published by others, it is now clear that in patients with diabetes, it is not necessary, and may be harmful to lower blood pressure too much,” Cooper-DeHoff noted.
“At this time, there is no compelling evidence to indicate that lowering systolic blood pressure below 130 mm Hg is beneficial for patients with diabetes; thus, emphasis should be placed on maintaining systolic blood pressure between 130 and 139 mm Hg while focusing on weight loss, healthful eating and other manifestations of cardiovascular morbidity to further reduce long-term cardiovascular risk," the authors concluded
The study was funded by Abbott Laboratories.