Insulin-Treated Diabetes Patients with CAD

Last year, results from the FREEDOM (Future REvascularization Evaluation in patients with Diabetes mellitus: optimal management of Multivessel disease) trial showed that patients with diabetes benefited more from coronary artery bypass grafting (CABG) than percutaneous coronary intervention (PCI). More specifically, the results found that CABG reduces mortality and myocardial infarction rates in comparison to PCI; however, the chance of stroke was increased among the CABG population.

Since those overall results were published in the New England Journal of Medicine, there have been several sub group analyses completed. One of the sub group analyses examined the association of clinical outcomes after revascularization by insulin-treated diabetes mellitus status and the respective effect of CABG versus PCI using first generation drug-eluting stents. Using the logrank test and Cox regression to assess the interaction between insulin-treated status and treatment received, the primary composite endpoint of major adverse cardiac events including death, stroke and myocardial infarction was analyzed. The findings of this sub group analysis were presented at the 25^th annual Transcatheter Cardiovascular Therapeutics scientific symposium.

In this sub group analysis, a total of 1,850 patients were randomized to either CABG or PCI, with 602 of those patients having insulin-treated diabetes. Of those 602 patients, 277 were randomized to the CABG group and 325 to the PCI group. Overall, the estimated percentage of those patients in the sub analysis with major adverse coronary events after five years, with the exception of stroke, was higher among those who underwent PCI (32% of insulin-treated patients vs. 25% of non-insulin-treated group) in comparison to CABG (24% of insulin-treated patients vs. 16% of non-insulin-treated patients). Those in the insulin-treated group who underwent CABG had a stroke rate of 7.5 in comparison to 3.7 in those who underwent PCI; whereas those in the non-insulin-treated group who underwent CABG or PCI had a rate of 4.3 vs. 1.7, respectively.

In conclusion, this sub group analysis showed there were more major adverse cardiovascular events in diabetic patients who are treated with insulin and have multivessel coronary artery disease However, regardless of the use of insulin or not, the clinical outcomes between CABG and PCI shown in the original trial were preserved.

Practice Pearls:

• Coronary artery bypass grafting is more beneficial than percutaneous coronary intervention in reducing mortality and myocardial infarction
• Rate of stroke is higher among CABG patients
• Patients with diabetes who are treated with insulin experience more major cardiovascular adverse events

Malloy, P. and Feldman, B. Cell-Autonomous Regulation of Brown Fat Identity Gene UCP1 by Unliganded Vitamin D Receptor. Molecular Endocrinology, October 2013, 27(10):1632–1642