Diabetes increases the risk for heart disease. Procedures to restore blood flow to the heart can help, but for those on insulin, these procedures may carry some risks.
About a quarter of people with diabetes in the US take insulin to help their cells take in blood sugar and use it for energy.
If any of these patients should require a procedure to restore blood flow to their coronary arteries, they may face a greater danger of heart attack or stroke compared to those who do not take insulin, according to a new study.
George Dangas, MD, professor of medicine at the Mount Sinai School of Medicine and director of Cardiovascular Innovation at the Zena and Michael A. Wiener Cardiovascular Institute of the Mount Sinai Medical Center, collaborated on this investigation to find out how insulin might affect outcomes for diabetes patients who required operations to restore blood flow to blocked arteries. The study involved 1,850 patients with both diabetes and multi-vessel disease.
To restore blood flow and treat their coronary artery disease, patients either received coronary artery bypass graft (CABG) surgery or percutaneous coronary intervention using drug-eluting stents (PCI/DES).
With CABG, a surgeon takes a healthy artery or vein from one part of the body (a leg, for example) and attaches it above the blockage and below the blockage to restore blood flow.
PCI is another term for coronary angioplasty. In this procedure, a catheter is inserted into an artery through the arm, wrist, upper leg or groin area, and then it is guided to the area of the blockage. A balloon at the end of the catheter is inflated, opening the blocked vessel and returning blood flow to the heart. To help keep the artery open, a stent (wire mesh tube) is placed in the reopened area.
Of the 894 patients who had CABG, 277 were being treated with insulin, and of the 956 in the PCI/DES group, 325 were getting insulin treatment.
After five years, 29 percent of the patients receiving insulin had a major adverse coronary event, such as a heart attack or stroke, compared to 19 percent of those not receiving insulin.
When comparing the two operations, PCI/DES patients had a greater likelihood of major adverse coronary events. Of the PCI/DES patients, 32 percent who were taking insulin had episodes and 25 percent who were not taking insulin had events. In comparison, of the CABG patients, 24 percent of the insulin patients had events and 16 percent of the non-insulin patients had episodes.
Stroke rates alone, however, were higher among CABG patients. Among those taking insulin, the stroke rate was 7.5 percent with CABG and 3.7 percent with PCI/DES. For non-insulin takers, the stroke rates were 4.3 percent versus 1.7 in the two groups.
“In patients with diabetes and multi-vessel, coronary artery disease there are more major adverse cardiovascular events in patients treated with insulin than in those not treated with insulin,” concluded the authors.
This study was a “sub group analysis” based on findings from the Future REvascularization Evaluation in patients with Diabetes mellitus: optimal management of Multivessel disease (FREEDOM) trial. Results reported from the FREEDOM trial last year in The New England Journal of Medicine showed that heart attack and death rates were lower in CABG patients compared to PCI/DES patients, but stroke rates in that group were higher.
Findings from this study confirmed those risks in patients, regardless of their insulin treatment.
This study was presented October 31 at the 25th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium, sponsored by the Cardiovascular Research Foundation.