SCRIPPS

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Catheter-Based Radiotherapy to Inhibit Restenosis After Coronary Stenting (SCRIPPS)

https://www.nejm.org/doi/pdf/10.1056/NEJM199706123362402?articleTools=true

Clinical Question

In patients with coronary restenosis after stenting with bare metal stents, does coronary stenting with bare metal stents plus catheter-based intracoronary radiotherapy reduce the rate of in stent restenosis compared to coronary stenting with bare metal stents alone?

Bottom Line

Treatment of ISR with coronary stenting with bare metal stents plus catheter-based intracoronary radiotherapy reduced the rate of in stent restenosis compared to coronary stenting with bare metal stents alone.

Major Points

Prior to the advent of drug-eluting stents (DES), the risk of in-stent restenosis (ISR) within bare metal stents (BMS) by neointimal proliferation was approximately 30%. Intravascular brachytherapy (IVBT) was developed to attempt to reduce the rate of neointimal proliferation.

The study was a randomized, blinded, single-center trial of 55 patients with restenosis of a coronary lesion that had been stented previously or was a candidate for stent placement who were randomized to revascularization with or without intravascular gamma radiation with iridium-192. The primary outcomes of late luminal loss (minimal luminal diameter immediately after the procedure minus the minimal luminal diameter at follow-up) and late loss index (late luminal loss divided by the immediate luminal gain) were significantly lower for the iridium-192 group at 6 months, and the clinical end-point of death, myocardial infarction, stent thrombosis, or revascularization of target lesion was also significantly lower for the iridium-192 group at 12 months.

Currently, guidelines favor the use of DES for initial treatment of ISR, as subsequent head-to-head studies of DES vs. IVBT (SISR and TAXUS V) favored DES, but a new role for IVBT has emerged in the subset of patients who have multiple layers of DES and continue to develop ISR. However, while this application has been studied favorably in matched cohorts, it has yet to be rigorously evaluated in a randomized controlled trial, and current ACC guidelines for the treatment of ISR favor DES over IVBT.

Guidelines

Current ACC guidelines for the treatment of ISR favor DES over IVBT.

Design

  • Randomized, blinded, single-center trial
  • N=55
    • Iridium-192 (n=26)
    • Placebo (n=29)
  • Setting: 1 center in the US
  • Enrollment: March to December 1995
  • Follow-up: 12.2  2.9 months
  • Analysis: Intention-to-treat
  • Primary outcomes: Late luminal loss; late-loss index

Population

Inclusion Criteria

  • Target lesion was the result of restenosis
  • Target vessel contained a stent already or was a candidate for stent placement
  • Target vessel was between 3 and 5 mm in diameter
  • Target lesion was 30 mm or less in length

Exclusion Criteria

  • Revascularization was unsuccessful
  • Revascularization was suboptimal
  • Angiographic evidence of thrombus was present
  • Stent had been implanted during an emergency procedure

Baseline Characteristics

Bulleted list of baseline characteristics of the study population. Point out between-group differences that are clinically relevant. Pick only one of the groups to summarize. For RCTs, please omit P-values if presented by the journal.

From the iridium-192 group.

  • Mean age: 69.8  9.7 years
  • Male sex: 73%
  • Elevated cholesterol level: 54%
  • Diabetes mellitus: 27%
  • Unstable angina: 42%
  • Previous myocardial infarction: 38%
  • History of hypertension: 65%
  • Previous restenosis:
    • Number: 2.1  1.4
    • >1: 52%
    • >2: 23%
  • Left ventricular ejection fraction: 46.7  19.8
  • Location of target vessel:
    • Saphenous vein: 23%
    • Left anterior descending: 31%
    • Ostial: 31%
    • Aorto-ostial: 12%
  • Lesion length: 12.89  7.05 mm
  • Lesion length > 10 mm: 58%

Interventions

  • Re-stenotic target lesion was stented, re-dilated if previously stented, or both to attempt to achieve a 0% residual stenosis
  • Intravascular ultrasound was performed
  • Randomized to iridium-192 (to receive 800 cGy farthest from the source and less than 3000 cGy closest to the source) or placebo
  • Repeat angiography was performed

Outcomes

Comparisons are iridium-192 vs. placebo.

Primary Outcome

Late luminal loss
0.38  1.06 vs. 1.03  0.97 (P=0.03)
Late-loss index
0.12  0.63 vs. 0.60  0.43 (P<0.01)

Secondary Outcomes

Clinical restenosis at 6 months (>/=50% stenosis of luminal diameter)
0.17 vs. 0.54 (P=0.01)
Repeat revascularization of target lesion at 12 months
0.12 vs. 0.45 (P=0.01)
Death, myocardial infarction, stent thrombosis, or revascularization of target lesion at 12 months
0.15 vs. 0.48 (P=0.01)

Subgroup Analysis

No subgroup analyses were performed.

Adverse Events

No adverse events other than the outcomes listed above were reported.

Criticisms

  • Given the relatively short follow-up, the long-term deleterious effects of intracoronary radiation to both coronary arteries and surrounding tissues are unknown.
  • It is difficult to protect operators from gamma radiation, given its penetrance of usual shielding.

Funding

The study was funded in part by unrestricted grants from Johnson and Johnson and SciMed Life Systems.

Further Reading