Scripps Coronary Radiation To Inhibit Proliferation Post Stenting - SCRIPPS

Description:

Intracoronary gamma radiation vs. placebo for restenosis prevention in CAD.

Hypothesis:

Safety and efficacy of catheter-based intracoronary gamma radiation plus stenting to reduce coronary restenosis in patients with previous restenosis.

Study Design

Study Design:

Patients Screened: Not given
Patients Enrolled: 55
Mean Follow Up: 12.2 months
Mean Patient Age: 69
Female: 25
Mean Ejection Fraction: 48%

Patient Populations:

Target lesion in a restenotic coronary artery that either already contained a stent or was a candidate for stent placement.
Previous treatment of the lesion more than four weeks before enrollment.
Reference vessel diameter between 3 and 5mm.
Target lesion that was 30 mm or less in length.

Exclusions:

Unsuccessful coronary-revascularization procedure or suboptimal result.
Angiographic evidence of thrombus.
Stents placed as an emergency procedure.

Primary Endpoints:

Late luminal loss and late-loss index at six months, as measured by quantitative angiography.

Secondary Endpoints:

Clinical restenosis, defined as angiographic evidence of 50 percent or greater stenosis of the luminal diameter at six months.
Need for revascularization of the target lesion at eight months.
Composite end point of death, myocardial infarction, and the need for repeated revascularization.

Drug/Procedures Used:

0.76mm (0.03-in.) ribbon containing sealed sources of either iridium-192 or placebo. Radiation dosing was 800 cGy to the target farthest from the radiation source, with no more than 3000 cGy delivered to the target closest to the source.

Concomitant Medications:

If the lesion was not already stented, single or, if required, tandem coronary stenting was performed. If stents had been placed previously, redilation was undertaken, and, in many cases, additional stents were placed within the original stent to optimize the angiographic result. In all cases, high-pressure (greater/equal 18 atm) balloon dilations were performed in an attempt to achieve a 0 percent residual stenosis within the stented segment. Intravascular ultrasonography was then performed to ensure that an optimal result had been achieved, provide a basis for comparison at six months, and allow dosimetric calculation by the radiation therapist.

Principal Findings:

Fifty-five patients were enrolled; 26 were assigned to the iridium-192 group and 29 to the placebo group. In one patient in the placebo group, the study ribbon could not be advanced completely across the target region because of excessive tortuosity of the vessel.

Early angiographic results were excellent in both groups , with an immediate luminal gain of 1.67+/-0.67 mm in the iridium-192 group and 1.83+/-0.97 mm in the placebo group (P not significant) and postprocedural stenosis of 7+/-22 percent and 5+/-23 percent, respectively (P not significant).

At 30 days, the initial procedure was successful in 96 percent of the patients in the iridium-192 group and 97 percent of those in the placebo group (P not significant). One patient in the iridium-192 group, who stopped taking ticlopidine on postoperative day 3, sustained a myocardial infarction due to stent thrombosis on day 18. There were no other myocardial infarctions and no deaths, and none of the patients underwent bypass surgery or had bleeding complications requiring blood transfusion or surgical intervention.

Angiographic studies were performed in 53 patients (96 percent) at a mean (+/-SD) of 6.7+/-2.2 months. The mean minimal luminal diameter at follow-up was larger in the iridium-192 group than in the placebo group (2.43+/-0.78 mm vs. 1.85+/-0.89 mm, P = 0.02). Late luminal loss was significantly lower in the iridium-192 group than in the placebo group (0.38+/-1.06 mm vs. 1.03+/-0.97 mm, P = 0.03). Angiographically identified restenosis (stenosis of 50 percent or more of the luminal diameter at follow-up) occurred in 17 percent of the patients in the iridium-192 group, as compared with 54 percent of those in the placebo group (P = 0.01). There were no apparent complications of the treatment.

No aneurysms were observed on any follow-up angiograms in either the iridium-192 group or the placebo group.

Significantly fewer patients reached the composite clinical end point (death, myocardial infarction, stent thrombosis, and revascularization of the target lesion) in the iridium-192 group (15 percent vs. 48 percent, P = 0.01).

Interpretation:

In this preliminary, short-term study of patients with previous coronary restenosis, stenting plus radiotherapy significantly reduced angiographic, ultrasonographic, and clinical indexes of restenosis. This benefit was achieved without an increase in adverse events at a mean follow-up of 12.2 months. Gamma radiation with iridium-192 is a promising new treatment for patients with restenosis.

References:

1. N Engl J Med 1997;336:1697-703. Final Results

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Stable Ischemic Heart Disease, Interventions and Imaging, Echocardiography/Ultrasound, Chronic Angina

Keywords: Blood Transfusion, Myocardial Infarction, Follow-Up Studies, Coronary Restenosis, Thrombosis, Ticlopidine, Constriction, Pathologic, Iridium Radioisotopes, Ultrasonography, Interventional, Gamma Rays, Stents


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