The SIROCCO Studies
The latest results from the SIROCCO studies—initial evaluations of drug-eluting stents in the SFA—show favorable outcomes.
The SIROCCO studies are the first clinical trials undertaken to evaluate the use of a drug-eluting stent to treat blockages in the superficial femoral artery (SFA). Principal Investigator Stephan H. Duda, MD, presented the most recent data from the trials at last month’s Transcatheter Cardiovascular Therapeutics meeting.
The trials are designed to evaluate the safety and efficacy of a sirolimus-eluting S.M.A.R.T. Stent (Cordis Corporation, a Johnson & Johnson company, Miami, FL) versus a bare S.M.A.R.T. Stent in patients with obstructive SFA disease &Mac179;70% or total occlusion. The clinicians who participated in the trials were satisfied not only with the results observed in the study arm, but also with those of the control group.
SIROCCO studies are multicenter, double-blind, randomized studies with a total of 93 patients enrolled in two phases. There were 36 patients enrolled in the first phase of the trial; 18 were assigned to each group. Patients in the study arm of the trial received either a slower-eluting formulation (n=5) or a fast-eluting formulation (n=13). The second phase of the SIROCCO trial enrolled 57 patients; 29 were randomized to the study group, which used the slower-eluting S.M.A.R.T. Stent, and 28 to the control.
Inclusion criteria included stenoses measuring 7 to 20 cm in length in the first phase of the study and 7 to 14.5 cm in length in the second phase. Occlusions allowed were 4 to 20 cm and 4 to 14.5 cm in length, respectively. In phase I of the study, more than 50% of the patients enrolled in each arm had total occlusions. Patients in the study arm of phase I had 100% moderate-to-severe calcification, compared with 46.7% in the control arm. There were no significant differences in baseline characteristics for patients in the study and control arms of the second phase of the trial. The primary endpoint for both phases was in-stent mean diameter (mm) via quantitative angiography within 6 months after stent placement.
At 6 months, both studies resulted in 0% binary in-stent restenosis (stenosis >50%) for the slower-eluting stents, compared with 17.6% binary in-stent restenosis for the phase I patients, and 7.7% for the phase II patients treated with the bare-metal stent. Three stent fractures occurred in SIROCCO II (6%, vs 24% in SIROCCO I). There were no clinical events associated with stent fractures.
The pooled data combining the slower-eluting stent groups compared to the combined control groups at 6 months resulted in 0% binary in-stent restenosis for the study arm and 11.6% binary in-stent restenosis for the control arm. Late loss in the study arm was 0.38 mm compared with 0.82 mm in the control arm. The mean stent diameter was 5.02 mm for the study arm and 4.58 mm for the control arm; this difference is statistically significant (P=.039). The target lesion revascularization rate was 0% for both groups at 6 months, and 5.8% at 24 months for the patients in the control arm of phase I of the study.
The 0% binary in-stent restenosis rates in the study cohorts of each trial are very promising early indicators of the overall success of sirolimus-eluting nitinol stents in the SFA. Dr. Duda emphasized that the data from SIROCCO II confirm the efficacy of the slower-release formulation identified in SIROCCO I. The bare S.M.A.R.T. Stent used in the control arms yielded impressive results, especially in binary in-stent restenosis rates and target lesion revascularization rates.
The pooled data from the SIROCCO study demonstrates that sirolimus enhances the bare S.M.A.R.T. Stent results at 6 months with a 54% reduction in late loss and a statistically significant difference in mean stent diameter. Duplex ultrasound and clinical follow-up are scheduled for 9 and 18 months for the patients in phase II of the trial.