Impact of Insulin Resistance on Neointimal Tissue Proliferation after 2nd-Generation Drug-Eluting Stent Implantation

Percutaneous coronary intervention is established as an effective treatment for patients with ischemic heart disease; in particular, drug-eluting stent implantation is known to suppress in-stent restenosis. Diabetes mellitus is an independent risk factor for restenosis, so reducing insulin resistance is being studied as a new treatment approach. In this prospective study, we sought to clarify the factors associated with in-stent restenosis after percutaneous coronary intervention, and we evaluated the homeostasis model assessment of insulin resistance (HOMA-IR) index as a predictor of restenosis. We enrolled 136 consecutive patients who underwent elective percutaneous coronary intervention at our hospital from February 2010 through April 2013. All were implanted with a 2nd-generation drug-eluting stent. We distributed the patients in accordance with their HOMA-IR index values into insulin-resistant Group P (HOMA-IR, ≥2.5; n=77) and noninsulin-resistant Group N (HOMA-IR, <2.5; n=59). Before and immediately after stenting, we measured reference diameter, minimal lumen diameter, and percentage of stenosis, and after 8 months we measured the last 2 factors and late lumen loss, all by means of quantitative coronary angiography. After 8 months, the mean minimal lumen diameter was smaller in Group P than that in Group N (1.85 ± 1.02 vs 2.37 ± 0.66 mm; P=0.037), and the mean late lumen loss was larger (0.4 ± 0.48 vs 0.16 ± 0.21 mm; P=0.025). These results suggest that insulin resistance affects neointimal tissue proliferation after 2nd-generation drug-eluting stent implantation.

After avandia: the use of antidiabetic drugs in patients with heart failure

Managing diabetes mellitus is an ongoing concern, especially in the presence of heart failure. Recent reports have drawn attention to adverse cardiovascular events associated with the use of thiazolidinediones, including rosiglitazone (Avandia). In 2011, the U.S. Food and Drug Administration implemented a stringent "restricted access program" for the prescription of Avandia. Other studies, which have revealed increased mortality rates in association with tight glycemic control, raise serious concerns about managing diabetes in heart-failure patients. Herein, we provide a perspective on the management of noninsulin-dependent diabetes in patients with heart failure. We point out that thiazolidinediones exert their major effects through insulin sensitization, which potentiates the action of insulin. A defining feature of insulin resistance is excess fuel supply and restricted rates of substrate utilization by the heart. We postulate that the use of excess insulin and insulin-sensitizing agents can lead to adverse cardiovascular events and contractile dysfunction through an increase of substrate uptake to an insulin-resistant heart that is already flooded with fuel. We include a table of antidiabetic agents and nonpharmacologic interventions aimed at lowering substrate supply, and of the respective clinical trials supporting their safety and efficacy. Although previously contraindicated in patients with heart failure, metformin appears to be both safe and effective therapy for diabetes in those patients. Because metformin reduces gluconeogenesis in the liver, we propose that the management of diabetes in heart-failure patients should target the source, rather than the destination, of excess fuel.