Results from a study comparing the outcomes of stenting vs percutaneous transluminal angioplasty (PTA) as a primary treatment modality for high-grade lesions of the infrapopliteal arteries in critical limb ischaemia (CLI), has concluded that stenting results in higher patency rates after six months, compared with PTA.
The study was undertaken to assess the validity of stent application in infrapopliteal arteries, as there are only a limited number of studies to have examined its potential. The researchers, lead by Professor Thomas Rand, University of Vienna, utilized the Carbostent (Sorin), a balloon expandable, stainless steal tubular stent with innovative multicellular design and a carbon coating. The stents used had a diameter of 2.0-2.4mm and a length of 15-20mm.
The multicentre, prospective, randomised study enrolled a total of 51 patients (95 lesions treated), who presented with Fontaine stages II and IV (rest pain, ischaemic ulcer and gangrene). The mean age of patients was 72.0 years (range 47-80) and one patient was treated in both limbs.
Clinical evaluation was performed by two observers, double-blinded, with thresholds for lesion restenosis for 50% to 70%. Statistical evaluation was performed on a lesion by lesion basis by Kapler-Meier estimated probability rates, with a primary endpoint of angiographioc patency rate of treated lesions. The patients population had a diabetes rate of 68.6%, equally distributed between the two groups and in a large number of patients the ankle-branchial index (ABI) could not be measured, therefore angiographic patency was applied.
After angiographic lesion indentification, patients were randomised to the PTA group (n=27, with 53 lesions) or stent group (n=24, with 42 lesions). Of the 51 patients, two died, three underwent amputation, one patient underwent major heart surgery, which did not allow further follow-up and eight patients were lost to follow-up. Therefore, the rate of major complications within 30-days was 3.9% (2/51), with a 30-day mortality rate 2% (1/51). The six months limb salvage rate regarding lmajor amputations was 98% (50/51).
In one patient, stent application failed because the stent could not pass through a heavily calcified stenosis. In one lesion, PTA alone ended with a high-grade dissection and was unsatisfactory. This lesion was treated by secondary stenting.
The investigators noted that follow-up was by clinical investigation and conventional angiography or spiral computer tomography (CT) and performed in 37 patients (57 lesions) six to 12 months after the procedure, or when clinically indicated. A breakdown of the 37 patients revealed 20 patients received PTA (32 lesions) and 17 patients received stents (27 lesions).
Rand revealed that for the stent group the cumulative primary patency at six months was 83.7% at the 70% restenosis threshold and 79.7% at the 50% restenosis threshold. For PTA, the primary patency at six months was 61.1% at the 70% restenosis threshold and 45.6% at the 50% restenosis threshold. Both results were statistically significant (p<0.05). The comparison of cumulative limb salvage in the two groups using the Kaplan-Meier method revealed no significant difference between them. At six months the estimated probability was 95% for the PTA group and 92% for the stent group. The researchers have initiated a larger ongoing multicenter study, which they hope will provide more reliable outcomes. In particular, Rand commented that with more data it might be possible to evaluate whether limb salvage in a Fointaine stage IV limb depends not only on patency but also on short-term improvement of CLI. In conclusion, Rand said that the study revealed that stenting was superior to PTA and they would expect the results to be mirrored in a larger patient population. It appears that based on the data, major advantages can be achieved in the reduction of lesions and limb salvage. Rand commented, “In particular, the study has shown that stents can work for short segmental lesions. In regards to longer lesions (15mm), stent stiffness is the key and the use of longer stents should be utilized, not short overlapping stents.”