News

Coronary Calcium Data Challenge Diabetes as Cardiac Risk Factor


 

Major finding: On CT examination, coronary artery calcium scores appeared similar in patients with diabetes, metabolic syndrome, and neither disease.

Source of data: The findings are based on a new analysis of data from the Multi-Ethnic Study of Atherosclerosis (MESA), which enrolled more than 6,800 people aged 45–84 who were free of cardiovascular disease at baseline. The new analysis focused on coronary CT exams involving those people with diabetes, metabolic syndrome, or neither disease at baseline.

Disclosures: Dr. Malik had no financial disclosures. One of her coauthors is a consultant for GE, and another associate is on the speakers bureau for Takeda.

ORLANDO — Nearly 40% of adults with diabetes had absolutely no evidence of coronary artery disease in a study of 881 patients, raising questions about the appropriateness of automatically considering diabetes to impart a risk equivalent to coronary disease.

The study findings also suggested that assessing coronary calcium may be a way to stratify the coronary disease risk of patients with diabetes, as well as those with metabolic syndrome and people without either of these conditions, Dr. Shaista Malik said at the annual scientific sessions of the American Heart Association.

“Our results raise questions as to whether diabetes should be considered a risk equivalent. They suggest that coronary artery calcium [CAC] screening may identify both low- and high-risk subsets in patients with metabolic syndrome and in patients with diabetes,” said Dr. Malik, a cardiologist at the University of California, Irvine.

“High-risk people, such as those with diabetes, have not been recommended for coronary calcium screening since aggressive treatment guidelines [for these patients] already exist,” Dr. Malik noted.

But her new analysis suggests that CAC scoring can play an important role in stratifying the coronary heart disease risk of patients with diabetes.

These results “add to the controversy over whether diabetes is truly a coronary heart disease risk equivalent,” commented Dr. Prakash C. Deedwania, professor of medicine and chief of cardiology at the University of California, San Francisco in Fresno. “Perhaps some patients [with diabetes], particularly those with longer-duration diabetes, are probably close to having a coronary heart disease risk equivalent, but there probably should be an effort made to identify the low- and high-risk patients within the diabetes cohort,” Dr. Deedwania said.

“I think it's the subset of patients with diabetes with a high CAC score who have been driving the association you see in other studies,” Dr. Malik said.

In conducting the study, she used data collected in the Multi-Ethnic Study of Atherosclerosis (MESA), which enrolled more than 6,800 people aged 45–84 who were free of cardiovascular disease at baseline. Most of the participants also underwent a coronary CT examination and had a complete risk factor assessment at baseline.

The new analysis focused on 881 people in MESA diagnosed with diabetes at baseline based on a fasting glucose level of 126 mg/dL or higher; 1,686 people diagnosed with metabolic syndrome at baseline based on the criteria of the National Heart, Lung, and Blood Institute; and 4,036 people with neither diagnosis. All 6,603 of these people underwent a baseline coronary CT examination to produce a CAC score. Follow-up tracked their incidence of coronary heart disease events over an average of 4.6 years. The mean age was 62 years; slightly more than half were women. About 40% were white and 28% were African American.

Baseline CAC scores showed that among the people with diabetes, 39% had no coronary calcium, 27% had mild coronary disease (CAC score of 1–99), 14% had moderate disease (CAC score of 100–399), and 21% had significant disease (CAC score of at least 400).

Among the individuals with metabolic syndrome and the people who had neither diagnosis, the percentages with no coronary calcium were higher, and the percentages with significant coronary disease were lower, but in general the CAC scores were similar in all three subgroups, Dr. Malik reported.

During follow-up, coronary events occurred in 33 people in the diabetes group, 43 in the metabolic syndrome group, and 52 in the people without either diagnosis. Calculation of the 10-year event rate within each of these three subgroups showed roughly similar rates within each CAC score category, especially among those with a CAC score of zero. (See box.)

“Many people with metabolic syndrome or diabetes have as low a risk as people without these conditions when their CAC score is minimal or absent,” Dr. Malik said.

She called for confirmation of these findings in people followed for longer periods of time.

Elsevier Global Medical News

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