Current perspectives on interventional treatment strategies in diabetic patients with coronary artery disease

New technologies aimed at percutaneous intervention in the small coronary artery

Percutaneous coronary intervention (PCI) of small vessels can be complicated by technically difficult access to the target lesion, an increased risk of major adverse cardiac events and in-stent restenosis requiring repeat revascularization. Conventional management of such lesions is with drug-eluting stent implantation; however, these have only partly attenuated the problem. In response, several medical device companies are competing to produce new technologies aimed at PCI in small coronary arteries. Such innovations include thin-strutted stents, stent-on-a-wire systems, drug-coated balloons, endothelial progenitor cell-catching stents and biodegradable stent systems. To date, none of these techniques have been sufficiently validated for use in small coronary arteries to justify a change in practice; however, small-vessel coronary artery disease is an increasingly common problem, and PCI of target lesions with reference vessel diameter <3.0 mm is likely to increase, especially in view of the increasing prevalence of diabetes, warranting further well-designed studies. The prospect of mounting a self-expandable biodegradable drug-eluting stent directly onto a guidewire could potentially be an exciting future development.

Acute and intermediate-term procedural results using cypher stenting to treat multi-vessel coronary artery disease

OBJECTIVE

We examined our experience using the sirolimus eluting stents (Cypher) as an alternative to surgical revascularization in carefully selected cohort of patients undergoing multi-vessel percutaneous coronary intervention.

METHODS

Fifty consecutive patients with multi-vessel disease who were good candidates for both surgical and percutaneous revascularization were included in the current analysis. All patients underwent a careful clinical evaluation prior to the intervention, and they were followed for procedural and clinical outcomes for nine months.

RESULTS

Mean age was 64+/-11 years (40 males, 30% diabetics) and 10 patients (20%) had three-vessel disease. Angina class was 2.7+/-0.6 at baseline. Overall, 116 lesions were treated using 122 stents (mean 2.4 stents per patient). Total mean stent length was 43+/-12 mm (range: 21-90 mm). Overall, one patient died during follow-up (2%), no patient had stroke or Q wave MI and one patient experienced non-Q myocardial infarction. There was no documented stent thrombosis and two patients (4%) underwent target-vessel revascularization. The hierarchical cumulative major adverse cardiac event rate was 8% and the cardiac event-free survival rate was thus 92%.

CONCLUSION

Multi-vessel stenting using Cypher stents is a viable treatment strategy in selected group of patients with multi-vessel coronary artery disease. It is associated with excellent intermediate-term clinical outcomes and thus it could serve as the primary revascularization strategy of choice in appropriate candidates.

Hyperglycemia alters PI3k and Akt signaling and leads to endothelial cell proliferative dysfunction

Diabetes mellitus is a major risk factor for the development of vascular complications. We hypothesized that hyperglycemia decreases endothelial cell (EC) proliferation and survival via phosphatidylinositol 3-kinase (PI3k) and Akt signaling pathways. We cultured human umbilical vein ECs (HUVEC) in 5, 20, or 40 mM d-glucose. Cells grown in 5, 20, and 40 mM mannitol served as a control for osmotic effects. We measured EC proliferation for up to 15 days. We assessed apoptosis by annexin V and propidium iodide staining and flow cytometry, analyzed cell lysates obtained on culture day 8 for total and phosphorylated PI3k and Akt by Western blot analysis, and measured Akt kinase activity using a GSK fusion protein. HUVEC proliferation was also tested in the presence of pharmacological inhibitors of PI3k-Akt (wortmannin and LY294002) and after transfection with a constitutively active Akt mutant. ECs in media containing 5 mM d-glucose (control) exhibited log-phase growth on days 7-10. d-Glucose at 20 and 40 mM significantly decreased proliferation versus control (P < 0.05 for both), whereas mannitol did not impair EC proliferation. Apoptosis increased significantly in HUVEC exposed to 40 mM d-glucose. d-Glucose at 40 mM significantly decreased tyrosine-phosphorylated PI3k, threonine 308-phosphorylated-Akt, and Akt activity relative to control 5 mM d-glucose. Pharmacological inhibition of PI3k-Akt resulted in a dose-dependent decrease in EC proliferation. Transfection with a constitutively active Akt mutant protected ECs by enhancing proliferation when grown in 20 and 40 mM d-glucose. We conclude that d-glucose regulates Akt signaling through threonine phosphorylation of Akt and that hyperglycemia-impaired PI3k-Akt signaling may promote EC proliferative dysfunction in diabetes.

Favorable effect of ?-radiation for in-stent restenosis: Effect of diabetes on angiographic and clinical outcomes

The purpose of this study was to examine the effect of vascular brachytherapy with gamma-radiation (gamma-RT) in patients with diabetes mellitus (DM) with coronary in-stent restenosis (ISR). In the Washington Radiation for In-Stent Restenosis (WRIST) trial, 130 patients with ISR were treated with (192)Ir or placebo. Of the patients enrolled, 44 (34%) had DM (18 of them treated with gamma-RT and 26 with placebo). Gamma-radiation therapy of ISR in diabetics resulted in similar procedural success and in-hospital outcome compared to nondiabetics. At 6-month follow-up, both DM and non-DM patients treated with gamma-RT had significantly lower target lesion revascularization (TLR), target vessel revascularization, and major adverse cardiac event rates compared to placebo. DM remains a powerful predictor of TLR and major adverse cardiac events even after treatment of ISR with gamma-RT.

Intracoronary brachytherapy, a promising treatment option for diabetic patients: Results from a European multicenter registry (RENO)

Despite advances in the interventional treatment of coronary disease, diabetics still have double the case fatality rate as nondiabetics. The purpose of this analysis from the Radiation in Europe With Novoste (RENO) registry was to assess the clinical and angiographic 6-month outcome of diabetic patients in comparison to nondiabetic patients after localized beta-radiation. A total of 1,098 patients (83.8% with in-stent restenosis) treated with the Novoste Beta-Cath system in Europe were enrolled in the RENO registry. Diabetes was, irrespective of the type of lesion treated, no significant risk factor for major adverse cardiac events or target vessel revascularization. Individuals with diabetes (n = 256) and without diabetes (n = 833) displayed no significant differences concerning clinical or angiographic endpoints. Vascular brachytherapy appears to be the first technique to even out the increased risk of diabetic patients undergoing percutaneous coronary interventions in the routine clinical setting. Thus, intracoronary brachytherapy represents a promising treatment option for diabetic patients.

Acute and Long-Term Outcomes of Rotational Atherectomy in Small (<3.0 mm) Coronary Arteries

Conventional balloon angioplasty (BA) of small coronary arteries (SCA) is followed by a high rate of restenosis. Rotational atherectomy may be effective as an alternate treatment of stenoses unsuitable for other devices. The purpose of this study was to assess the efficacy of RA in the treatment of SCA. A retrospective analysis was performed of 226 lesions in 159 consecutive patients who underwent RA of SCA (mean diameter = 2.36 +/- 0.49 mm). One hundred forty-eight lesions (65.5%) were type B2 or C of AHA/ACC criteria. Follow-up angiography was performed at 3 and 6 months after the procedure. Procedural success was achieved in 96.9% of patients. The mean burr-to-artery ratio was 0.74 +/- 0.17. Adjunctive BA and stent implantation were needed in 94.2% and 22.6% of lesions, respectively. Minimal lumen diameter (MLD) increased from 0.66 +/- 0.35 mm to 1.97 +/- 0.58 mm (P < 0.01). Angiographic complications consisted of acute reclosure (3.5%), no reflow/slow flow (12.4%), and coronary artery perforation (1.8%). No death, Q-wave myocardial infarction (MI), or coronary artery bypass graft (CABG) occurred during the initial hospitalization. Restenosis rates at 3 and 6 months were 40.6% and 44.2%, respectively, and target lesion revascularization (TLR) rates were 28.5% and 33.0%, respectively. Restenosis and TLR rates during follow-up were comparable among patients who underwent RA + adjunctive BA versus patients who underwent RA + stenting. Long-term clinical follow-up was complete in 143 patients over a mean period of 348 +/- 166 days. The survival free from cardiac death, MI, CABG or repeated BA was 59.6% at 1 year. In conclusion, RA of SCA has relatively high restenosis rates, but may be appropriate for more complex, calcified lesions unsuitable for other devices.

Increased secretion of insulin during oral glucose tolerance test can be a predictor of stent restenosis in nondiabetic patients

Insulin is known to stimulate proliferation and migration of vascular smooth muscle cells. As the predominant mechanism of restenosis after stent implantation is neointimal tissue proliferation, one can expect a relationship between hyperinsulinemia and restenosis in these patients. The aim of this study was to determine whether hyperinsulinemia during oral glucose tolerance test is a predictor of the development of restenosis after stent implantation in nondiabetic patients. We prospectively studied 52 nondiabetic patients with effort angina who underwent elective stent implantation for single-vessel coronary artery disease. In order to increase the statistical power of the study, numerous exclusion criteria were applied. All patients were subjected to a 75 g oral glucose tolerance test a day before the stent implantation and underwent follow-up angiography 6 months later. Plasma insulin levels in fasting (6.77 +/- 1.57 vs. 5.36 +/- 1.35 micro U/ml; P = 0.005), at 30 min (102.48 +/- 10.6 vs. 47.74 +/- 12.75 micro U/ml; P = 0.001), 1 hr after (120.23 +/- 14.1 vs. 63.08 +/- 12.62 micro /ml; P = 0.001), 2 hr after (63.58 +/- 8.64 vs. 34.88 +/- 6.82 micro /ml; P = 0.001), and 3 hr after (25.71 +/- 5.65 vs. 23.02 +/- 4.61 micro /ml; P = 0.04) loading were significantly higher in patients with stent restenosis than in patients without stent restenosis. Insulin area and insulin area/glucose area were also significantly higher in patients with stent restenosis than in patients without (219.5 +/- 23.8 vs. 118.9 +/- 21.8, P = 0.001, and 0.62 +/- 0.09 vs. 0.33 +/- 0.06, P = 0.001, respectively). By multiple logistic regression analysis, insulin area during oral glucose tolerance test was found to be an independent predictor of stent restenosis (OR = 1.12; 95% CI = 1.01-1.25; P = 0.031). In conclusion, nondiabetic patients with hyperinsulinemia during oral glucose tolerance test have a high risk for restenosis after stent implantation, and performing this simple test before intervention may be useful for the prediction of stent restenosis.

The effect of intracoronary radiation for the treatment of recurrent in-stent restenosis in patients with diabetes mellitus

OBJECTIVES

The purpose of this study was to examine the effect of intracoronary radiation therapy (IRT) in diabetic patients with in-stent restenosis (ISR).

BACKGROUND

Diabetic patients are at an increased risk for restenosis, repeat revascularization procedures and late mortality after percutaneous coronary interventions and stenting. Intracoronary radiation therapy, utilizing both gamma and beta-emitters, has been shown to reduce the rate of ISR.

METHODS

The study group consisted of 749 consecutive patients with ISR who were treated with either IRT or placebo in randomized trials and registries at our center. Diabetic patients (252 radiation and 51 placebo) were compared with nondiabetic patients (371 radiation and 75 placebo).

RESULTS

In-hospital outcomes were similar between diabetic and nondiabetic patients treated with and without radiation. At six-month clinical and angiographic follow-up, there was a significant reduction in the binary restenosis (63.8% vs. 15.7%, p < 0.0001), target lesion revascularization (66.7% vs. 17.6%, p < 0.0001) and target vessel revascularization (TVR) (70.6% vs. 22.9%, p < 0.0001) rates in diabetic patients treated with radiation compared to placebo. Comparisons between the placebo arms detected a trend towards higher restenosis (63.8% vs. 48.4% p = 0.13) and TVR (70.6% vs. 56.0%, p = 0.14) in diabetic versus nondiabetic patients. In contrast, diabetic and nondiabetic patients treated with IRT experienced similar restenosis (15.6% vs. 10.7% p = 0.33) and TVR (22.9% vs. 28.2% p = 0.41) rates.

CONCLUSIONS

In diabetic patients with ISR, intracoronary radiation significantly reduced the recurrence of ISR compared to placebo. Additionally, similar rates of restenosis and revascularization procedures were achieved in irradiated diabetic and nondiabetic patients. In view of these results, IRT should be considered as a valuable therapeutic alternative in all diabetic patients with ISR.

Comparison of stenting with balloon angioplasty for lesions of small coronary vessels in patients with diabetes mellitus

PURPOSE

We sought to assess whether stenting is a better treatment strategy than percutaneous transluminal coronary angioplasty (PTCA) for lesions in small coronary vessels of diabetic patients.

METHODS

We studied the 100 diabetic patients who were enrolled in the Intracoronary Stenting or Angioplasty for Restenosis Reduction in Small Arteries trial; 51 patients were randomly assigned to receive a stent and 49 to PTCA alone. Small vessels were considered those with a reference diameter of 2.0 to 2.8 mm. The primary endpoint of the study was the incidence of restenosis, defined as 50% or greater diameter stenosis at follow-up angiography (performed in 83 of the 100 patients). The secondary endpoint was clinical restenosis, defined as the need for target vessel revascularization within 1 year.

RESULTS

Angiographic restenosis occurred in 18 (44%) of the patients who received a stent and in 19 (45%) of the PTCA patients (P = 0.90). Target vessel revascularization was needed in 13 (25%) of the stent patients and 10 (20%) of the PTCA patients (P = 0.55). During the 1-year follow-up, 5 (10%) of the stent patients died or incurred myocardial infarction, compared with 3 (6%) of the PTCA patients (P = 0.50).

CONCLUSIONS

Patients with diabetes who undergo percutaneous coronary interventions for lesions in small vessels have an especially high risk of restenosis that does not appear to be attenuated by stenting.