Routine coronary angiography didn't reduce cardiac events in asymptomatic diabetics

Screening all diabetic patients for coronary artery disease (CAD) using coronary computed tomography angiography (CCTA) did not reduce the rate of mortality or cardiovascular events, a study found.

The FACTOR-64 study was a randomized clinical trial in which 900 patients with type 1 or type 2 diabetes without symptoms of CAD were recruited from 45 sites within the Intermountain Healthcare system in Utah from July 2007 to May 2013, with follow-up to August 2014. Results appeared in the Dec. 3 Journal of the American Medical Association.

The control group comprised 448 patients receiving guideline-based optimal diabetes care. These patients continued to be treated by their primary care physicians, with the recommendations to target an HbA1c level less than 7.0%, LDL cholesterol levels less than 100 mg/dL (2.6 mmol/L), and systolic blood pressure less than 130 mm Hg.

There were 452 patients randomly assigned to CAD screening with 64-slice CCTA. Scan results were divided into 4 categories based on CAD severity. After CCTA, patients received medical management based on the severity category. Those with normal coronary arteries continued standard diabetes care. Patients with mild proximal disease to severe proximal or distal CAD were recommended to begin aggressive care to reduce risk factors. This included diet and exercise and targeting LDL less than 70 mg/dL (1.8 mmol/L), HDL greater than 50 mg/dL (1.3 mmol/L), triglycerides less than 150 mg/dL (1.7 mmol/L), HbA1c less than 6.0%, and systolic blood pressure less than 120 mm Hg.

The study's primary outcome was a composite of all-cause mortality, nonfatal MI, and unstable angina requiring hospitalization, and the secondary outcome was a composite of CAD death, nonfatal MI, and unstable angina. After a mean follow-up of 4.0 years, the primary outcome event rates were not significantly different between the CCTA and the control groups (6.2% [28 events] vs. 7.6% [34 events]; HR, 0.80; 95% CI, 0.49 to 1.32; P=0.38). The composite secondary end point also did not differ between groups (4.4% [20 events] vs. 3.8% [17 events]; HR, 1.15; 95% CI, 0.60 to 2.19; P=0.68).

Based on these results, routine use of CCTA in diabetics is not justified, the authors concluded. An editorialist noted that the most likely explanation for the lack of effect was the excellent baseline medical therapy for control of factors such as LDL cholesterol and systolic blood pressure, which led to a low rate of major cardiac events in the control group.

The editorialist wrote, “Until future studies provide evidence of better patient outcomes with an imaging strategy, these results suggest that an ‘ounce of prevention’ with optimal guideline-directed medical therapy in asymptomatic patients with diabetes is more important than cardiac imaging.”