September 12, 2016
2 min read

Coronary CTA provides valuable CAD risk stratification in patients with diabetes

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Patients with diabetes with nonobstructive and obstructive CAD according to coronary CTA are at higher risk for all-cause mortality and major adverse cardiac events at 5 years vs. patients without diabetes, according to recent findings.

In the study, Philipp Blanke, MD, of the department of radiology and division of cardiology, University of British Columbia, Vancouver, and colleagues reviewed the CONFIRM registry to identify 1,823 patients with available 5-year clinical follow-up data who had diabetes but no history of CAD.

These patients were propensity-score matched to 1,823 patients without diabetes (mean age, 61.8 years; 54.4% men). Coronary CTA was used to evaluate the severity and extent of CAD at baseline and relative to outcomes in participants with and without diabetes.

CAD as assessed by CTA was categorized as follows: none (0% stenosis), nonobstructive (1% to 49% stenosis) or obstructive (50% stenosis). Participants were evaluated for symptoms before undergoing coronary CTA. The presence of cardiac risk factors also was evaluated before coronary CTA.
The study’s primary endpoint was defined as time to mortality from all causes. In the subgroup of 973 patients with diabetes for whom results were available, the secondary endpoint was time to major adverse CV event, defined as death, MI, unstable angina or late coronary revascularization (> 90 days).

CAD, diabetes and mortality

The researchers found that 382 (10.5%) patients died; 136 (7.5%) were nondiabetic and 246 (13.5%) were diabetic. This equated to an annualized mortality rate of 0.02 per person-year (95% CI, 0.018-0.022) overall, 0.027 per person-year (95% CI, 0.024-0.031) in patients with diabetes and 0.014 (95% CI, 0.012-0.016) in those without diabetes. A lack of CAD as assessed by coronary CTA was related to a low overall annual mortality rate of 0.01 (95% CI, 0.008-0.13).

Jamal S. Rana

 Compared with the propensity-matched patients without diabetes, those with diabetes but without CAD on CTA did not show an increased mortality risk (risk-adjusted HR = 1.32; 95% CI, 0.78-2.24). Patients with diabetes who also had nonobstructive CAD demonstrated an increased risk for death vs. those without diabetes (HR = 2.1; 95% CI, 1.43-3.09) and also had a higher mortality risk vs. patients without diabetes but with obstructive CAD (P < .001). A risk-adjusted hazard analysis among those with diabetes revealed that both per-patient obstructive and nonobstructive CAD were related to increased risk for all-cause death vs. patients with no atherosclerosis on coronary CTA (nonobstructive disease HR = 2.07; 95% CI, 1.33-3.24; obstructive disease HR = 2.22; 95% CI, 1.47-3.36), according to the researchers.

Preventive measures needed

In a related editorial, Jamal S. Rana, MD, PhD, of the division of cardiology, Kaiser Permanente Oakland Medical Center, and Ron Blankstein, MD, of the cardiovascular imaging program of the cardiovascular division and the department of radiology, Brigham and Women’s Hospital and Harvard Medical School, discussed the likely effect of these findings on clinical practice.

“First, it is important for clinicians to recognize that once CAD is identified in a diabetic, even if nonobstructive, that person is more likely to have diffuse plaque, faster plaque progression and more events,” they wrote. “Therefore, intensification of both lifestyle and pharmacologic preventive measures should be employed.” – by Jennifer Byrne

Disclosure: Blanke reports consulting for Circle Imaging, Edwards Lifesciences, HeartFlow, Neovasc and Tendyne. Please see the full study for a list of the other researchers’ relevant financial disclosures. Rana reports receiving a research grant from Regeneron/Sanofi. Blankstein reports no relevant financial disclosures.