ASNC: Ischemia Resolution in Diabetes Tied to Risk Factor Control

SAN DIEGO, Sept. 11 -- There was unexpected resolution of silent myocardial ischemia for almost 80% of diabetic patients over three years, possibly because of aggressive therapy, according to a study reported here.
SPECT perfusion imaging showed that 56 of 71 (79%) patients with abnormal initial scans had resolution of ischemia at follow-up imaging three years later, Frans Wackers, M.D., of Yale, reported at the American Society of Nuclear Cardiology meeting. The study results were published simultaneously in the September issue of Diabetes Care.
Patients with ischemia resolution were significantly more likely to receive ACE inhibitors, statins, and aspirin, in accordance with American Diabetes Association recommendations for coronary risk reduction (P=0.03 to P<0.001). Ischemia resolution also was associated with longer duration of treatment with the drugs.
"This was not a treatment study, but it is not inconceivable that [ischemia resolution] was due to aggressive treatment of cardiovascular risk factors," said Dr. Wackers.
The findings came from analysis of follow-up data in the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study. Begun in 2000, DIAD involved 1,123 patients with type 2 diabetes, who were randomized to adenosine-sestamibi stress perfusion imaging or to "natural history" follow-up with no perfusion imaging. The primary endpoints were prevalence of silent myocardial ischemia and five-year cardiac event rate.
Dr. Wackers' focused on the 522 patients randomized to stress perfusion imaging. Of the original cohort, 358 patients had SPECT imaging at baseline and after three years of follow-up. Perfusion images were evaluated by a blinded consensus panel of investigators and by computerized quantitative analysis.
The trial's working hypothesis was that the prevalence of asymptomatic ischemia would increase over time. Dr. Wackers said investigators were surprised to find that the overall prevalence of ischemia decreased from 20% (71 patients) at baseline to 12% (43 patients) at follow-up.
Review of the data showed that 28 of the 43 patients with asymptomatic ischemia at follow-up represented new cases. The remaining 15 patients had abnormal baseline scans, meaning that 56 of the original cases had resolved during follow-up. Results were similar whether interpreted by the consensus panel or computer.
When investigators evaluated the change in medication usage between perfusion stress tests, they found that 34% of patients were on ACE inhibitors at baseline, 40% were on statins, and 42% were taking aspirin. Three years later, the figures were 42% for ACE inhibitors, 59% for statins, and 69% for aspirin.
Analysis of medication usage in the 56 patients who had resolution of ischemia showed that 50% were on ACE inhibitors at three years, 63% were on statins, and 71% were taking aspirin. In contrast, medication usage among the 28 patients with new ischemia was 39% for ACE inhibitors, 50% for statins, and 61% for aspirin.
Moreover, patients who had resolution of asymptomatic ischemia had a median exposure to the three medications combined of 59 months, compared with 45 months for the patients with new ischemia (P=0.04).
Data on cardiac event rates are not yet available. However, Dr. Wackers said, the results provide strong support for aggressive treatment of cardiac risk factors in patients with type 2 diabetes.
Dr. Wackers listed multiple relationships with commercial interests.Primary source: American Society of Nuclear CardiologySource reference: Wackers FJ et al. "Unanticipated resolution of silent myocardial ischemia (SMI) in type 2 diabetes (T2DM): 3-year follow-up in the DIAD study. American Society of Nuclear Cardiology 2007. Abstract LB-05.