Sirolimus-Eluting Stents for Chronic Total Coronary Occlusions

Sirolimus-Eluting Stents for Chronic Total Coronary Occlusions: A Randomized Comparison of Bare Metal Stent Implantation With Sirolimus-Eluting Stent Implantation for the Treatment of Chronic Total Coronary Occlusions (PRISON II)

Primary intracoronary stent placement after successfully crossing chronic total occlusions (CTO) decreases the high restenosis rate at long-term follow-up compared with conventional balloon angioplasty. Several studies have shown the efficacy of sirolimus-eluting stents in selected groups of patients. Whether sirolimus-eluting stents are superior to bare metal stents in CTO is unknown. In this prospective randomized trial, bare metal stent implantation will be compared with sirolimus-eluting stent implantation for the treatment of chronic total coronary occlusions. A total of 200 patients will be followed up for 6, 12, and 24 months with angiographic follow-up at 6 months. Quantitative coronary analysis will be performed by an independent core laboratory. The primary end point is the binary angiographic restenosis and reocclusion rate at 6 month follow-up.

Since data from the 2 landmark studies, the BENESTENT and STRESS studies, showed that coronary stenting significantly decreases restenosis as compared with conventional balloon angioplasty, this treatment modality has shown to be superior in an increasing number of indications. Percutaneous coronary intervention of chronic total occlusions (CTO), however, is still limited by high restenosis rates. Although coronary stenting using bare metal stents significantly decreases restenosis in CTO, restenosis rates still reach 32% to 55%.

In 200 patients with CTO randomized in the PRISON I study, we demonstrated a restenosis rate of 22% after bare metal stent implantation as compared with 33% after conventional balloon angioplasty. During the past few years, sirolimus (rapamycin), a cytostatic macrocyclic lactone with anti-inflammatory and antiproliferative properties, delivered from a polymer-encapsulated stent was shown to almost eliminate the risk of restenosis in selected groups of patients.

In this prospective, randomized, single-blind trial we enrolled 200 patients with chronic total occlusions: 100 were randomly assigned to receive bare metal BxVelocity™ stents, and 100 to receive sirolimus-eluting Cypher™ stents. The primary endpoint was angiographic binary restenosis rate at six months follow-up. Secondary endpoints were a composite of major adverse cardiac events, target vessel failure, in-stent and in-segment minimal lumen diameter, percentage diameter stenosis, and late luminal loss at six months follow-up. Clinical long-term follow-up will performed up till 24 months

Inclusion Criteria:

• Estimated duration of the chronic total coronary occlusion of at least two weeks
• Evidence of ischemia related to the target vessel (signs of ischemia during an abnormal exercise test, defined as ST depression of at least 1.0 mm that is horizontal or down-sloping or up-sloping ST depression of at least 2.0 mm or signs of ischemia found during nuclear imaging with exercise, dobutamine or adenosine).

Exclusion Criteria:

• The lesion could not be crossed
• The use of heparin, aspirin and clopidogrel was prohibited
• Severe renal failure (creatinine>250µmol/L)
• Patients were unwilling or unable to complete follow-up.