Endovascular brachytherapy to inhibit coronary artery restenosis: An introduction to the scripps coronary radiation to inhibit proliferation post stenting trial

Abstract

This year is the 100th anniversary of the use of ionizing radiation to treat disease. Since the turn of the century, many benign and malignant diseases have been treated with radiation therapy (RT). Through the decades, however, the application of RT in the treatment of benign diseases has largely disappeared-supplanted by other medical or surgical therapies. RT has most recently been committed to the treatment of malignancies to such a degree that the specialty was renamed radiation oncology. However, a continued. though very limited, role for RT has persisted in the treatment of certain benign hyperplastic disorders. RT significantly inhibits excessive fibroblast activity. Judicious clinical use of low-dose RT is highly effective in inhibiting such benign conditions as conjunctival pterygia. keloid scars. and aggressive fibromatosis. Excessive bone formation by the osteoblast, a derivative of the fibroblast. is successfully inhibited by low-dose RT and thereby inhibits heterotopic ossification. Although such benign hyperplasia disorders are significant clinical entities, the main thrust of RT continues to be the treatment of malignancies. With the coming millennium, a new therapeutic application of RT in benign disease promises to open new vistas previously unimagined. Studies have just begun in using RT to prevent vascular restenosis. RT may provide a powerful tool to solve what has become a vexing problem in vascular disease. In this review, we shall discuss early preclinical evidence that endovascular brachytherapy may inhibit coronary artery restenosis. We shall also introduce and describe the Scripps Clinic’s ongoing trial of endovascular RT in the prevention of coronary artery restenosis. The Scripps Coronary Radiation to Inhibit Proliferation Post Stenting trial (SCRIPPS) is the first attempt to use catheter-based intracoronary ionizing radiation in a prospective double-blinded randomized study. The study’s objective is to determine the initial safety and efficacy in reversing and preventing coronary artery restenosis by adding lowdose RT to today’s optima1 conventional cardiovascular therapy. This review will hopefully also provide a basis to understand the rationale and some of the potential benefits of applying radiation in the treatment of coronary artery restenosis.