Bare Metal Stents Hold Their Own in Contemporary Endovascular Treatment of Chronic Mesenteric Ischemia

Use of ostial flaring techniques during endovascular stent placement in the superior mesenteric artery (SMA) for chronic mesenteric ischemia (CMI) has put patency outcomes for bare metal stents on par with those for covered stents, which are significantly more expensive devices. So finds a retrospective review of Cleveland Clinic experience (J Vasc Surg. 2019 Jul 18 [Epub ahead of print]), which also shows that outcomes of endovascular therapy in this setting have steadily improved over time.

“In the current era of advanced endovascular techniques, bare metal stents deliver patency that’s comparable to that with covered stents in the treatment of chronic mesenteric ischemia,” says Sean Lyden, MD, Cleveland Clinic’s Chair of Vascular Surgery and senior author of the study. “Our experience indicates that choosing the more costly option is no longer defensible without evidence from a randomized comparative study.”

Which stent is best? Addressing a lack of consensus

Although open surgical bypass remains the gold standard for treating CMI, endovascular interventions are justified on the basis of a lower risk of morbidity and mortality. But clear evidence is lacking on whether covered stents — which cost three to five times more than bare metal stents — should be standard for endovascular therapy.

An earlier review of 225 patients from 2000 to 2010 (J Vasc Surg. 2013;58:1316-1323) found better outcomes with covered stents (92% primary patency at three years, vs. 52% with bare metal stents), but the covered stent data were based on only nine patients.

Cleveland Clinic experience

From 2003 to 2014 at Cleveland Clinic, 150 patients with CMI underwent a bare metal endovascular intervention on the celiac axis (56 vessels) or the SMA (133 vessels), with 38 patients undergoing concurrent interventions to both. In addition to the overall results, early (2003-2008) and late (2009-2014) cohorts were separately analyzed.

“We leveraged our experience with fenestrated stent grafting to flaring visceral stents to allow for better ostial expansion and easier retreatment of restenosis during this period,” notes Dr. Lyden. Over the study period, this approach was adopted for the majority of the procedures, rising from 44% in the early cohort to 72% in the late cohort.

Celiac axis. Overall, primary patency was 86% at one year and 66% at three years. Secondary patency at three years was 100%. Univariate analysis for demographics, atherosclerotic risk factors, presenting symptoms, stent diameter and ostial flaring revealed no significant differences. No differences were found between outcomes from the early and late periods.

SMA. Overall, primary patency was 81% at one year and 69% at three years; secondary patency was 96% at three years. The following trends were found at three years:

• Advanced age (≥70 years) was associated with improved primary patency (hazard ratio [HR] = 0.96; 95% confidence interval [CI], 0.92-1.00; P = 0.028).
• Chronic total occlusion was associated with poorer primary patency than stenosis (HR = 2.38; 95% CI, 1.03-5.47; P = 0.042).
• Patients in the later cohort had better primary patency than those the earlier cohort (77% vs. 59%; P = 0.016).
• Patients who underwent ostial flaring had better primary patency than those who did not (79% vs. 55%; P = .004).

After multivariate analysis, ostial flaring was the only factor found to be associated with improved SMA patency at three years (HR = 0.29; 95% CI, 0.12-0.69; P = .006).

Because only seven patients received a covered stent during the study period, their numbers were insufficient for inclusion in the analysis. “However, our data suggest contemporary outcomes for flared bare metal stents in the SMA position have excellent results and do not justify use of covered stents,” Dr. Lyden observes.

Key takeaways

According to the authors, important conclusions from the review include the following:

• Endovascular treatment for CMI continues to improve. Previous experience from Cleveland Clinic (i.e., 2001-2005) was associated with a 7.7% mortality rate (J Vasc Surg. 2008;47:485-491), mostly from acute mesenteric ischemia. Moreover, in this current study, all serious complications (e.g., death, mesenteric ischemia and acute renal failure requiring dialysis) occurred in the early cohort.
• Ostial flaring improves patency in the SMA. Dilating the stent at the ostium to a diameter of about 7 to 9 mm secures the stent (usually against aortic plaque) and makes it easier to access for later procedures. Patency rates for bare metal stents in the SMA were comparable to reported rates for covered stents.
• The celiac axis does not appear to benefit from ostial flaring. This result, which is likely due to the median arcuate ligament, appears to make self-expanding stents preferable to balloon-expandable stents in this setting.
• Younger patients may be better candidates for open surgery. Age younger than 70 was associated with a higher proportion of SMA occlusion, which was likely responsible for the poorer endovascular outcomes. This was despite the younger patients undergoing flaring proportionally more often than the older group.

“The increasing use of endovascular techniques as an alternative to open surgery for treating chronic mesenteric ischemia makes it critical to monitor outcomes data and continue to develop refinements,” concludes Dr. Lyden.

Image at top reprinted from Haben et al., Journal of Vascular Surgery 2019 Jul 18 [Epub ahead of print], with permission from the Society for Vascular Surgery.