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Screening in Type 2s for CAD Does Not Reduce Risk of Cardiac Events

Screening for coronary artery disease (CAD) in patients with Type 2 diabetes did not result in a significant reduction in the rate of myocardial infarctions (MI) or cardiac death compared with patients who were not screened, according to a study.

The findings were presented by Frans J. Th. Wackers, MD, Yale University School of Medicine, New Haven, Connecticut, at a JAMA media briefing at the National Press Club in Washington, DC.

Dr. Wackers and colleagues of the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study group tested prospectively whether systematic screening for CAD would identify higher-risk individuals and beneficially affect their risk of MI or cardiac death.

The study included 1,123 participants with Type 2 diabetes and no symptoms of CAD. Patients were randomly assigned to be screened (n = 561) for CAD with adenosine-stress radionuclide myocardial perfusion imaging (MPI), or not be screened (n = 562). The average follow-up was 4.8 years.

The overall cumulative 5-year cardiac event rate was 2.9% and averaged 0.6% per year — lower than anticipated. The researchers found that when analysed according to randomisation, there were 15 events (7 nonfatal MIs; 8 cardiac deaths; 2.7%) in the screening group versus 17 events (10 nonfatal MIs; 7 cardiac deaths; 3.0%) in the no-screening group.

Of those in the screened group, 409 participants (78%) with normal results and 50 (10%) with small MPI defects had lower event rates than the 33 with moderate or large MPI defects; 0.4% per year versus 2.4% per year.

Coronary angiography was performed within 120 days after screening 4.4% of 561 participants, including 15% of 33 with moderate or large defects. In comparison, only 3 (0.5%) of 562 participants in the no-screening group underwent angiography within 120 days after randomisation.

The overall rate of coronary revascularisation was low in both groups: 5.5% in the screened group and 7.8% in the unscreened group. During the course of the study there was a significant and equivalent increase in primary medical prevention with aspirin, statins and angiotension-converting enzyme (ACE) inhibitors in both groups.

“The strategy of routine screening for CAD in patients with Type 2 diabetes is based on the premise that testing could accurately identify a significant number of individuals at particularly high risk and lead to various interventions that prevent cardiac events,” the authors wrote.

“However, the results of the DIAD study would appear to refute this notion…participants had a low cardiac event rate and the identification of participants with abnormal screening results did not serve to eliminate their risk over 5 years of follow-up.”

“However, rather than viewing this study as a negative screening study, clinicians might consider the results as a positive message: patients with Type 2 diabetes without symptoms to suggest CAD, receiving contemporary medical care, close follow-up, and appropriate diagnostic evaluation for symptoms of ischemia have relatively favorable outcomes in the current era,” the authors concluded.

JAMA. 2009 Apr 15;301(15):1599-601.
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Fitter Diabetic Men Live Longer: Among middle-aged and older men with Type 2 diabetes, their capacity for exercise is related to their likelihood of dying over a 7-year period, according to a new study.  Between 1986 and 2007, 1,703 African American men and 1,445 Caucasian men with Type 2 diabetes completed a maximal exercise test. This classified them as “low-fit,” “moderate-fit,” or “high-fit.”  During 7 years of follow-up, “a graded reduction in mortality risk was noted with increased exercise capacity for both races,” the researchers report in the medical journal Diabetes Care. Among African Americans, the death rate was 46 percent in the low-fit group, 27 percent in the moderate-fit group, and 15 percent in the high-fit group. Corresponding rates among Caucasians were 37 percent, 19 percent, and 9 percent. “Thus, our findings support the notion that higher exercise capacity is associated with lower all-cause mortality in men with Type 2 diabetes, independent of socioeconomic status. The findings, they add, “extend the public health message regarding the health benefits of cardiorespiratory fitness to men with diabetes … and that health care professionals should encourage diabetic subjects to initiate and maintain a physically active lifestyle consisting of moderate-intensity activities.”