STENT: Strategic Transcatheter Evaluation of New Therapies -- Paclitaxel- vs Sirolimus-Eluting Stents in Diabetic Patients

Luis Gruberg, MD, FACC

Disclosures

July 20, 2006

Editorial Collaboration

Medscape &

"These results will likely only fuel the ongoing debate about the superiority of one stent over the other."

Presenter: Charles A. Simonton, MD (Carolinas Heart Institute, Charlotte, North Carolina), on Behalf of the STENT Group

The advent of drug-eluting stents (DES) -- the paclitaxel-eluting stent (PES) and the sirolimus-eluting stent (SES) - has revolutionized interventional cardiology by significantly reducing restenosis and, in turn, reducing target lesion revascularization rates when compared with bare-metal stents. Nevertheless, these 2 stents differ in their metallic structure, polymer coating, drug delivered, and time of drug release -- factors that may influence outcomes.

A recent head-to-head comparison of these 2 stents yielded conflicting results, especially in diabetic patients -- a population who remain at high risk following DES placement. Data from real-world practice, as collected in a national database, may help to elucidate the role of DES in these high-risk patients.

The Strategic Transcatheter Evaluation of New Therapies (STENT) Group[1] is the first registry in the United States for DES procedures, which started enrollment immediately after the US Food and Drug Administration approved SES implantation. The registry is a secure Web-based database containing data on DES interventions from 9 coronary interventional laboratories from the southeast United States that are prospectively entered by dedicated personnel. Researchers hope to include data from approximately 8000-10,000 interventions per year.

STENT Group researchers conducted the current analysis to compare the late clinical outcomes of diabetic patients treated with either PES or SES. Available data from 8 of the 9 laboratories were used and complete in-hospital and 9-month data are available for analysis.

Methods and Results

Between May 2003 and February 2005, a total of 12,185 interventions were performed, of which 6680 (63%) were DES-only procedures. In the present analysis, 9-month follow-up data were available for 5566 patients who underwent PES-only or SES-only procedures (patients treated with both stents were excluded from the analysis). And of the 5566 patients who underwent DES treatment, 1680 (30.2%) had diabetes. Table 1 shows the breakdown of the study population by category relating to status of diabetes and type of stent received.

Table 1. STENT Group: Diabetic Patients by Treatment
SES PES Total
All diabetic patients (n) 875 805 1680
Non-insulin-treated patients (n) 612 570 1182
Insulin-treated patients (n) 263 235 498
PES = paclitaxel-eluting stent; SES = sirolimus-eluting stent

Comparisons were made between the stents among patients with non-insulin- and insulin-treated diabetes. Baseline clinical characteristics were similar within each comparison. However, in non-insulin-treated patients, there was a higher incidence of family history of coronary artery disease in the SES vs PES groups (Table 2). Clinical status on admission for non-insulin- and insulin-treated patients was not significantly different between the 2 stent groups (Table 2).

Table 2. STENT Group: Baseline Clinical Characteristics and Clinical Status on Hospital Admission
Non-insulin-Treated Insulin-Treated
SES
(n = 612)
PES
(n = 570)
SES
(n = 263)
PES
(n = 235)
Clinical characteristics
Age (yrs) 64 64 62 62
Male gender (%) 64 63 50 49
Hypercholesterolemia (%) 75 78 74 72
Hypertension (%) 83 85 84 81
Smoking (%) 59 57 57 51
Family history of CAD (%) 36* 28 41 34
S/P MI (%) 25 21 27 21
S/P CABG (%) 16 17 22 25
S/P PCI (%) 32 28 35 35
Clinical status on hospital admission
Stable angina (%) 11.3 12 10 11
Unstable angina (%) 47 50 51 51
Non ST-elevation MI (%) 20 18 17 18
ST-elevation MI (%) 10 11 5 6
Ejection fraction (%) 52 52 50 51
Heart failure (%) 5 5 8 5
*P = .005, all other values P = NS

CABG = coronary artery bypass graft; CAD = coronary artery disease; MI = myocardial infarction; PCI = percutaneous coronary intervention; PES = paclitaxel-eluting stent; SES = sirolimus-eluting stent; S/P = status-post

In the non-insulin group, there were more urgent procedures with SES, but a significantly higher incidence of emergent intervention in the PES group (Table 3). In addition, SES patients were more likely to be treated with bivalirudin.

Table 3. STENT Group: Procedural and Pharmacotherapy Characteristics
Non-insulin-Treated Insulin-Treated
SES
(n = 612)
PES
(n = 570)
SES
(n = 263)
PES
(n = 235)
Elective procedure (%) 26 35* 31 39
Urgent procedure (%) 66* 53 62 56
Emergent (%) 9 11* 6 6
Multivessel procedure (%) 11 10 10 13
GP IIb/IIIa use (%) 59 61 55 46
Bivalirudin (%) 31 25 36 32
Stent length (mm) 28 30 28 31
*P = .0001; P < .05; P = .02

GP = glycoprotein; PES = paclitaxel-eluting stent; SES = sirolimus-eluting stent

Within both the non-insulin-treated and insulin-treated groups, PES patients had more complex lesions, longer lesion lengths, and smaller diameter vessels as compared with SES-treated patients within each of the diabetic groups.

There was no significant difference in 9-month clinical outcomes between the 2 stents within each diabetic-treatment group (Figures 1 and 2). However, there was a strong trend toward a higher rate of major adverse cardiac events (MACE) in the SES group among insulin-treated patients (Figure 2) when adjusted for differences in patient populations (HRadjusted 0.48, P = .05).

Figure 1. STENT Group: non-insulin-treated patients --9-month clinical outcomes.
Figure 2. STENT Group: insulin treated patients --9-month clinical outcomes.
Conclusions
  1. The STENT Group represents the first US, multicenter, prospective registry for DES and can effectively enroll and follow a high percentage of all interventional procedures at several institutions.

  2. PES and SES procedures show similar and very favorable late clinical outcomes in diabetic patients overall, with restenosis rates similar to those reported in prior studies of nondiabetic patients.

  3. In insulin-treated diabetic patients there is a trend favoring PES over SES for late MACE, but this needs to be confirmed by continued enrollment and a prospective randomized controlled trial.

Viewpoint

With a > 90% penetration of DES into the US market, the question regarding the treatment of coronary artery disease is no longer whether to use DES or bare-metal stents, but rather, which of the currently available DES systems should be used. Nowhere is this conflict more evident than in the diabetic population, where restenosis continues to plague patients even after DES implantation. The dilemma is further accentuated by contradictory results from 2 recently completed randomized studies (Sirolimus-eluting and Paclitaxel-eluting Stents for Coronary Revascularization [SIRTAX][2] and REALITY).[3]

The present analysis from the STENT Group, a large database from the "real world" shows that, clinically, there are no significant differences between the 2 stents (as predicted). In addition, the data suggest that there may be a small advantage to the use of PES in insulin-treated patients. These results will likely only fuel the ongoing debate about the superiority of one stent over the other. For the time being, however, both stents seem to provide an adequate treatment alternative in diabetic patients, yielding very low restenosis rates.

References
  1. Simonton CA, Brodie B, Cheek C, et al. Comparative late clinical outcomes of paclitaxel and sirolimus-eluting coronary stents in diabetic patients from a large prospective multicenter registry: Results from the Strategic Transcatheter Evaluation of New Therapies (STENT) Group. Program and abstracts from the Innovation in Intervention: i2 Summit 2006; March 11-14, 2006; Atlanta, Georgia. Abstract 2402-9.

  2. Windecker S, Remondino A, Eberli FR, et al. Sirolimus-eluting and paclitaxel-eluting stents for coronary revascularization. N Engl J Med. 2005;353:653-662.

  3. Morice MC, Colombo A, Meier B, et al; REALITY Trial Investigators. Sirolimus- vs paclitaxel-eluting stents in de novo coronary artery lesions: the REALITY trial: a randomized controlled trial. JAMA. 2006;295:895-904.

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