medwireNews: The presence of diabetes markedly increases the risk for major adverse cardiovascular events (MACE) even among people with very little detectable myocardial ischemic damage, shows an analysis of the REFINE SPECT registry.
Only people with no myocardial stress perfusion defect had a consistent low MACE risk that was not affected by having diabetes. By contrast, people who had diabetes and very minimal ischemic damage had a MACE risk equivalent to that of someone without diabetes who had moderate-to-severe ischemic damage.
“Therefore, patients with diabetes with even minimal perfusion defect may require medical attention, and those patients could be managed as if they had significant perfusion defects,” the researchers write in Diabetes Care.
The REFINE SPECT registry comprises patients with suspected or established coronary artery disease who were referred for single-photon emission computed tomography, and this analysis included 2951 people with diabetes who were matched by propensity score to an equal number of people without diabetes.
Piotr Slomka (Cedars-Sinai Medical Center, Los Angeles, California, USA) and co-researchers assessed MACE risk in relation to stress total perfusion deficit (TPD), which they say is an objective means of quantifying ischemic damage, contrary to subjective assessments used in previous studies.
During a median follow-up of 4.6 years, MACE occurred in 16% of people with diabetes and 10% of those without. Despite the higher rate of MACE among the people with diabetes, they did not have more myocardial ischemic damage than those without, with near identical proportions of both groups falling into the different TPD categories.
Around 10% of both groups had no detectable myocardial ischemic damage, with a TPD of 0%, and the annualized MACE rate did not significantly differ between the subgroups with and without diabetes, at 1.2% and 1.0%, respectively.
But as ischemic damage appeared, so did a gap between the people with and without diabetes. For those with very minimal ischemia (TPD >0% and <1%; 22–24% of patients) the corresponding MACE rates were 2.4% versus 1.4%, which amounted to a significant 1.68-fold risk increase for people with diabetes.
For people with minimal ischemic damage (TPD ≥1% but <5%), who comprised the largest proportion of the population at 46–47%, MACE rates were a significantly different 3.2% versus 2.1% in those with and without diabetes, equating to a 1.45-fold risk increase. And the corresponding rates for those with moderate or severe ischemic damage (TPD >10%) were 9.4% versus 3.9%, giving a 2.35-fold risk increase.
The researchers calculated that a person with diabetes and a very minimal TPD of just 0.5% had the same MACE risk of a person without diabetes but with a TPD of 8%.
However, the effect of diabetes on MACE risk was even more pronounced at higher TPD, which they say “suggests that patients with diabetes are more vulnerable to a greater myocardial ischemic burden than patients without diabetes are, even if they have similar risk factors.”
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Diabetes Care 2019; doi:10.2337/dc19-1360