Interim 6-Month Data Presented for FlexStent System in the SFA

October 22, 2009—In the late-breaking trials session at the Vascular Interventional Advances meeting in Las Vegas, Nevada, William A. Gray, MD, presented interim 6-month clinical results on the use of the FlexStent femoropopliteal self-expanding stent system (Flexible Stenting Solutions, Inc. [FSS], Eatontown, NJ) in the superficial femoral artery (SFA).

The clinical results originated from the first-in-man study conducted in New Zealand by principal investigator Andrew Holden, MD, at Auckland City Hospital and FSS's supplementary study conducted in Germany by principal investigator Dierk Scheinert, MD, at Leipzig Heart Center of the University of Leipzig.

The primary objective at both sites was to evaluate the safety and efficacy of the FlexStent as measured by the absence of in-stent binary restenosis (patency) using duplex ultrasound (DUS) at 1-, 6-, and 12-month intervals. The primary safety endpoint was freedom from major adverse cardiovascular events at 30 days. The secondary safety endpoint was monitoring and assessing adverse events for 12 months.

The primary efficacy endpoint was patency via DUS peak systolic velocity ratio, of which < 2.4 is considered patent. Several secondary efficacy endpoints were evaluated, including: primary-assisted and secondary patency through 12 months, change in Rutherford class through 12 months, change in ankle brachial index at pretreatment through 12 months, and walking improvement questionnaire through 12 months. Also, the absence of stent fracture was evaluated at the 6- and 12-month visits using standard x-ray evaluation methods.

Dr. Gray reported that in the Auckland first-in-man FlexStent study major inclusion criteria were patients age 35 to 80 years with a single de nova lesion in the SFA, lesion length < 100 mm, target reference vessel diameter of 3.5 to 5.5 mm, diameter stenosis > 50% and Rutherford Category from 2 to 4. Major inclusion criteria in the Leipzig safety and efficacy study were patients age 35 to 80 years with a single de nova SFA lesion and proximal popliteal lesion, with lesion length < 135 mm, target reference vessel diameter of 3.5 to 7.5 mm, diameter stenosis > 50% and Rutherford Category from 2 to 4.

The pooled (N = 35) baseline demographics were as follows: 22 males (63%) and 13 females (37%) with mean age of 65.8 ± 11.8 years, hypertension (83%), hypercholesterolemia (71%), smokers (60%), and diabetes (34%). Six patients (17%) were Rutherford Category 2; 27 (77%) patients were Rutherford Category 3; one patient (3%) was Rutherford Category 4; and one patient (3%) was Rutherford Category 5.

Pooled lesion characteristics included two patients (5.7%) with lesions in the proximal SFA, 17 patients (48.6%) with lesions in the mid-SFA, and 16 patients (45.7%) with lesions in the distal SFA. The pooled mean target reference vessel diameter was 5.1 ± 0.7 mm with mean stenosis of 92 ± 11%. The mean lesion length was 87 ± 29 mm.

The following are the postprocedural angiographic results for Auckland (n = 15), Leipzig (n = 20), and pooled (N = 35), respectively. In-stent mean lesion diameters were 5 ± 0.6 mm, 5.2 ± .8 mm, and 5.1 ± 0.7 mm. Residual stenoses were 1.8 ± 7%, 2 ± 4.1%, and 1.9 ± 5.4%. Periprocedural lesion success (restenosis < 30%) was 100% in all three study sets.

In both studies, the 30-day safety endpoints showed no adverse events (0%), including death, stroke, myocardial infarction, significant embolization, significant distal embolization, and emergent surgical revascularization, thrombosis, or renal failure.

The interim 6-month efficacy endpoints demonstrated 100% freedom from major adverse cardiovascular events and no fractures (0%) in both studies. The overall primary patency rate was 92.3% (one patient in each study of 13 patients) with an average lesion length of 75.8 mm in the Auckland study and 95 mm in the Leipzig study. In the pooled set (N=26), there was a 92.3% patency rate with an 86.6-mm average lesion length. Among the secondary endpoints, average treadmill, ankle brachial index, and Rutherford scores improved. To date, there have been no additional stenoses or fractures for those patients who have reached 9 and 12 months, reported Dr. Gray.

The European Union Registry will study the FlexStent's safety and efficacy in 100 patients enrolled at three or four hospitals. Dr. Scheinert will be the principal investigator of the study, which is expected to start in November 2009. The FlexStent trial in the United States, to be conducted under an investigational device exemption, will commence in early 2010 with Dr. Gray as principal investigator.