Studies have indicated that patterns of restenosis affect long-term outcomes following retreatment in the superficial femoral artery. Gary Ansel, OhioHealth/Riverside Methodist Hospital, Columbus, USA, presented results at the Leipzig Interventional Course (LINC; 26–29 January 2016, Leipzig, Germany) showing that, when in-stent restenosis occurs, it is more often focal with a drug-eluting stent (Zilver PTX, Cook Medical), whereas it is more diffuse with bare metal stents. The drug-eluting device, according to Ansel, yields less restenosis, less reintervention and reduced plaque burden.
Drug-eluting stents (Zilver PTX), Ansel said, are the only current option for endovascular intervention in the superficial femoral artery that provides stable patency, “proven by five-year data”, and added that previous studies of stents and drug-eluting balloons have shown that “lesion length affects patency outcomes”.
Tosaka et al (J Am Coll Cardiol 2012;59:16–23) have demonstrated that patterns of restenosis after treatment with bare metal stents are predictors of in-stent restenosis and occlusion. In the study, 133 patients with in-stent restenosis were analysed: 29% had class I in-stent restenosis (focal, ≤50mm); 38% had class II (diffuse, ≥50mm); and 33% class III (totally occluded). At two years, restenosis rates after treatment with angioplasty were 49.9%, 53.3%, and 84.8%, respectively. The study also showed that more diffuse than focal lesions occluded after reintervention. The same patterns were seen by Armstrong et al (Cath Card Interv 2013;82:1168–74) in a study analysing reintervention with adjunctive therapies (atherectomy and/or stenting). Ansel also noted that the VIBRANT study (Viabahn) has suggested that focal restenosis may lead to fewer clinical issues and may allow up to 50% higher flow rate compared to diffuse restenosis.
He went on to question whether restenosis patterns impact the need for reintervention, and added, “Data from the randomised ZILVER PTX trial showed that the 12-month restenosis rate was 9.7% with Zilver PTX and 25.3% with Zilver bare metal stent, and target lesion revascularisation was 5.3% with the drug-eluting device vs. 17.2% with the bare metal stent. The percentages of restenoses requiring intervention were 54.6% with Zilver PTX vs. 70% with the bare metal stent. There was significant reduction in restenosis and target lesion revascularisation with Zilver PTX and, for patients with restenosis, Zilver PTX further reduces the need for treatment.”
To further investigate patterns of restenosis and drug elution, an analysis of studies with Zilver PTX (ZILVER PTX randomised study, FLEX EU study and Japan PMS study) was conducted. It identified 14 in-stent restenoses treated with the Zilver bare metal stent and 19 with Zilver PTX. The Zilver PTX group had more patients with Rutherford class 3 (63.2% vs. 28.6%) and longer lesions (15.7cm vs. 12.2cm), whereas the bare metal stent group had a larger number of occlusions (64.3% vs. 50%).
When looking at the types of restenosis, Ansel noted that in-stent restenosis patients treated with the bare metal stent presented with diffuse restenosis, whilst those treated with Zilver PTX had more focal lesions. Additionally, plaque burden area was lower with Zilver PTX (17%) vs. bare metal stent (28%)—a 39% relative reduction (p=0.03).
Ansel concluded by saying that Zilver PTX reduces the rate of restenosis by 41% in relation to the Zilver bare metal stent. It also reduces the rate of reintervention by 47% and plaque burden by 39% when compared to the bare metal stent. In terms of treatment, he noted that focal restenoses are easier, faster and cheaper to retreat than diffuse restenosis.