Coronary artery calcium levels predict CVD mortality in type 2 diabetes

Coronary artery calcification is a “striking” independent predictor of cardiovascular mortality in patients with type 2 diabetes, said investigators.
     An analysis of data on participants in the Diabetes Heart Study showed that the highest levels of coronary artery calcification (CAC) were associated with a more than 11-fold risk for death from a cardiovascular cause, reported Subhashish Agarwal, MD, a cardiology fellow at Oakwood Hospital and Medical Center, and colleagues at Wake Forest University in Winston-Salem, North Carolina.
     “We had a paper published in May showing that coronary artery calcium in diabetes is a strong predictor of all-cause mortality, either cardiovascular or non-cardiovascular, and we hypothesized most of this was driven by cardiovascular mortality,” Agarwal said in an interview.
     The investigators reviewed data on 1123 participants in the Diabetes Heart Study, a family study in which siblings concordant for type 2 diabetes and unaffected family members were followed for an average of 7.4 years.
     The participants chosen for the analysis had complete data on covariates and on CAC score (Agatston Score) measured at baseline with fast-gated helical coronary artery computed tomography.
     The participants were divided into five groups based on their CAC scores from lowest (0 to 9) to highest (1000 or higher).
     The authors found that 86% of patients (963) had a CAC of 10 or greater. During follow-up, 8% of patients died from cardiovascular disease (CVD), including myocardial infarction, cardiac arrest, congestive heart failure, and stroke.
     In multivariate analysis, the odds ratios (OR, with 95% confidence interval [CI]) for CVD mortality by CAC group were:

CAC 0 to 9: reference

CAC 10 to 99: 2.93 (95% CI, 0.74–19.55)

CAC 100 to 299: 3.17 (95% CI, 0.70–22.22)

CAC 300 to 999: 4.41 (95% CI, 1.15–29.00)

CAC 1000 or greater: 11.23 (95% CI, 3.24–71.00)

     The adjusted OR for CVD mortality increased by a factor of 2.24 for each standard deviation increment of log-transformed CAC score.
     In a receiver operating characteristic analysis showing area under the curve (AUC) with and without CAC as predictors of CVD mortality, the AUC for traditional risk factors was 0.70. When log CAC was added to those risk factors, the AUC increased to 0.75 (P<.0001), indicating that CAC can be a valuable addition to the panel of predictive markers for CVD-related mortality in diabetics.
     “In this work, we have shown that coronary artery calcium has incremental value beyond the traditional Framingham Heart Study risk factors,” Agarwal said.