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Oral Rapamycin to Prevent Human Coronary Stent Restenosis

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Oral Rapamycin to Prevent Human Coronary Stent Restenosis
Background: Recent human trials with rapamycin-eluting stents have shown very low restenosis rates. However, the high costs of these devices preclude their use in routine angioplasty, especially when considering multiple stenting. We evaluated whether orally administered rapamycin inhibits in-stent neointimal growth in patients with unstable angina.
Methods: We enrolled 15 patients successfully treated with the implantation of a single stent in a single de novo lesion in native coronary arteries. Correct stent expansion and apposition were corroborated with intravascular ultrasound scanning in all patients. Patients received aspirin, clopidogrel, and atorvastatin for 6 months. Rapamycin was administered in a loading dose of 5 mg, followed by 2 mg/day for 4 weeks.
Results: The reference diameter was 3.4 ± 0.4 mm, lesion length was 11.2 ± 2 mm, lesion type B1 was 36%, and lesion type B2 was 64%. After the procedure, in-stent minimal lumen diameter and diameter stenosis (DS) were 3.3 ± 0.4 mm and 0.3% ± 7.5%, respectively. At 10 days, plasma levels of rapamycin were 7.95 ± 2.6 ng/mL. At 6 months, angiographic determinations demonstrated an in-stent minimal lumen diameter of 2 ± 1 mm, an in-stent DS of 41.3% ± 28.0%, and an in-stent late loss of 1.4 ± 1.1 mm. Binary restenosis (>50% DS) was present in 6 of 15 patients (40%). Target lesion revascularization (coronary artery bypass grafting) was performed in 2 of 15 patients (13.3%). There were no serious adverse events during the 6-month period of follow-up, but 1 patient had severe heartburn caused by esophagitis, and another patient had herpes zoster at the end of the protocol.
Conclusions: Oral rapamycin was well tolerated, but did not suppress in-stent neointimal growth in this small group of patients.

Although stent implantation reduces the risk of restenosis compared with other percutaneous coronary interventions (PCI), angiographic in-stent restenosis continues to limit the long-term success of this approach. Only recently, drug-eluting stents with rapamycin or paclitaxel have emerged as a potential solution, by reducing neointimal proliferation. However, their high costs, especially when considering multiple stenting, is a limitation for the widespread use of these devices.

Some investigators believe that oral delivery of these drugs might be preferable to their incorporation into stents, because this would enable repeat dosing and would also be much less expensive.

The purpose of this pilot study was to evaluate the hypothesis that oral rapamycin could decrease neointimal proliferation after elective coronary stenting.

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