Coronary and aortic calcium burden strongly predictive of cardiovascular events in type 2 diabetes

Coronary artery calcium and abdominal aortic calcium both predicted future cardiovascular events in a Veterans Administration population with type 2 diabetes. The relationship between calcium scores and cardiovascular events was independent of standard cardiovascular risk factors, said Peter Reaven, MD.

He presented the findings from the RACED (Risk Factors Atherosclerosis and Clinical Events in Type 2 Diabetes) study, a substudy of the larger VA Diabetes Trial. RACED included 324 patients with type 2 diabetes who were recruited from seven centers. All participants had measurements of coronary artery calcium and abdominal aortic calcium on computed tomography scans at baseline and were followed for 5 to 7 years for the development of cardiovascular events. During that time, 88 events occurred, most of which were coronary heart disease events.

As part of the randomized VA Diabetes Trial, the patients had been randomized to either a standard glucose-lowering strategy or an intensive strategy. The achieved median hemoglobin A1c levels were 8.4% in the standard arm and 6.9% in the intensive arm.

Coronary artery calcium scores were divided into four quartiles; the lowest quartile consisted of score of 0 to 10 and the highest quartile had scores greater than 400. An extremely high burden of coronary artery calcium (score > 400) was present in 40% of the participants, said Dr. Reaven, from the Phoenix VA Health Care System.

There was a stepwise increase in the percentage of subjects with events with increasing coronary artery calcium scores, he said. Using the group with the lowest coronary calcium scores as the reference, the risk of an event increased by 70% among subjects in quartile 2 of coronary calcium scores (11 to 100), by 4.9-fold among those with coronary calcium scores in quartile 3 (101 to 400), and by 7.5-fold in the group with the highest coronary calcium scores.

There was a significant but less robust relationship between abdominal aortic calcium score and the development of cardiovascular events.

The risk of a cardiovascular event was increased five-fold in those individuals with a baseline coronary calcium score of greater than 100 compared with those with a baseline coronary calcium score of less than 100.

High coronary Ca better predictor of events
High coronary calcium was a better predictor of having an event than was a previous cardiovascular event, said Dr. Reaven.

"There was little effect of treatment assignment [standard or intensive control] in persons in the highest coronary artery calcium category," he said. "There was a substantial reduction in events in those assigned to intensive therapy in the lowest coronary artery calcium category."