SAN FRANCISCO — Patients with type 2 diabetes and no cardiac symptoms or prior coronary artery disease had a surprisingly low risk of nonfatal MI or cardiac death with or without routine screening in a study of 1,119 patients.
The 3% event rate over a 5-year period (or 0.5% per year) included cardiac death in 1.5% of 558 patients who were randomized to routine screening for silent ischemia, and 1.2% of 561 patients who were getting usual care. Nonfatal heart attacks occurred in 1.2% of the screening group and in 1.8% of the control group. The differences between groups were not statistically significant, Dr. Frans J. Wackers said at the annual scientific sessions of the American Diabetes Association.
The ADA recommends routine stress testing in patients with diabetes who have cardiac symptoms, are starting an exercise regimen, or have no cardiac symptoms but have multiple risk factors for coronary artery disease.
That approach appears to be sufficient. “Systematic screening for coronary artery disease cannot be recommended for asymptomatic patients with type 2 diabetes” based on results presented from the DIAD (Detection of Ischemia in Asymptomatic Diabetes) study, said Dr. Wackers, professor of diagnostic radiology and medicine at Yale University, New Haven, Conn.
The study enrolled adults aged 50–75 years with type 2 diabetes who had no known coronary artery disease, normal resting ECGs, and no stress testing in the prior 3 years. The screening group underwent adenosine myocardial perfusion imaging (MPI), which detected inducible ischemia in 22%. Except for the initial MPI in the screening group, diagnostic testing in both groups was at the discretion of the patients' physicians.
Cumulative mortality at the 5-year mark was higher for patients with moderate to large defects detected on MPI (12%) than for patients with small or no defects detected (2% mortality for each) or for patients with nonperfusion abnormalities such as ischemic ECG changes (7%).
Screening results predicted cardiac outcomes, but the rates of cardiac events or mortality did not differ between groups. The mortality rate was 3% at 5 years.
The unexpectedly favorable 5-year prognosis probably reflects the benefits of contemporary strategies to optimize medical therapy, Dr. Wackers said.
“In the standard-care group, there was a fair number of stress tests and angiograms performed. I think clinicians made the right decisions,” suggesting that routine screening is not needed, he said.
Patients in the standard-care group were more likely to get nonprotocol stress tests (30%) than were those in the screening group (21%). The proportion of those tests that identified abnormalities was similar between groups (24% of 118 additional tests in the screening group, and 26% of tests in 170 patients in the control group).
Coronary angiograms were as likely to be ordered for patients in the control group as in the screening group (12% vs. 14%), but were significantly more likely to identify abnormalities in the control group (44 of 66 angiograms, or 66%) than in the screening group (40 of 80 angiograms, or 50%). The use of oral medications increased in both groups over time, but did not differ between groups at baseline or at the end of the study.
Characteristics of the two groups were comparable. Patients had a mean age of 62 years and an 8-year history of diabetes. The baseline hemoglobin A1c level was 7.1%. The cohort was 54% male, and 22% were ethnic minorities. The cohort probably is representative of the general population with type 2 diabetes. Patients were overweight, with a mean body mass index of 31 kg/m
Dr. Wackers has received research support from Bristol Myers Squibb Medical Imaging and from Astellas Pharma, which makes cardiac imaging agents.
'Systematic screening for coronary artery disease cannot be recommended for asymptomatic patients.' DR. WACKERS