Long-Term Data Presented for Medtronic's Endurant AAA Stent Graft

April 18, 2014—Medtronic, Inc. (Santa Rosa, CA) announced that new clinical data supporting the company’s Endurant abdominal aortic aneurysm (AAA) stent graft system were presented at the 35^th Charing Cross International Symposium, which was held April 5–8 in London, United Kingdom.

Prof. Hence Verhagen, MD, presented 3-year data from a subset analysis of the ENGAGE postmarket global registry. Prof. Giovanni Torsello, MD, presented long-term results from the PANDORA trial. Prof. Verhagen is from Erasmus Medical Center in Rotterdam, the Netherlands, and Prof. Torsello is from St. Franziskus Hospital in Muenster, Germany.

The Endurant AAA stent graft system received European CE Mark approval for endovascular aneurysm repair (EVAR) in June 2008. In December 2010, the US Food and Drug Administration approved the device for EVAR treatment in the United States. The next-generation Endurant II AAA stent graft received CE Mark approval in December 2011 and US Food and Drug Administration approval in May 2012, noted Medtronic.

The company stated that both ENGAGE, which is sponsored by Medtronic and conducted at 79 sites worldwide, and PANDORA, which was independently conducted at two sites in Germany, affirm the Endurant stent graft’s durable, consistent, and proven outcomes across a broad spectrum of patient types and anatomical features. Though the studies differ in size, scale, and scope, both datasets highlight low rates of aneurysm-related mortality and reintervention, stent graft migration, and conversion to open surgery through 3 to 5 years of follow-up.

The ENGAGE registry has enrolled more than 1,200 patients at 79 sites on six continents since Endurant received CE Mark approval. Medtronic advised that 10-year follow-up is now planned for all enrolled patients. The latest subset analysis of data from ENGAGE compared the influence of neck length on patient outcomes at 3 years of follow-up. Two-year follow-up data were presented last year at Charing Cross by Prof. Verhagen.

In this context, neck length is the span of healthy aortic tissue between the top of the aneurysm and the lowest renal artery, which cannot be occluded safely. Neck length determines how much of a landing zone is available for the proximal end of the stent graft. It is the single anatomical characteristic that most limits patient eligibility for EVAR, noted Medtronic.

Medtronic reported that the 3-year data from ENGAGE demonstrated similarly strong outcomes in patients with short neck lengths (10 mm to < 15 mm) and standard neck lengths (≥ 15 mm). Historically, shorter neck lengths have been associated with limited eligibility for EVAR and higher rates of adverse events. The Endurant stent graft is approved for use in patients with neck lengths of ≥ 10 mm, depending on the device’s regional labeling for angulation (60º in the United States; 75º in Europe and other countries that recognize the CE Mark), noted the company.

The analysis included 48 patients with neck lengths of 10 mm to < 15 mm, 79 patients with neck lengths of 15 mm to < 20 mm, and 364 patients with neck lengths of ≥ 20 mm. The 3-year results demonstrated no statistically significant differences across these three groups on any of the following outcomes: aneurysm rupture (0%, 0%, 0.3%); conversion to open surgery (0%, 0%, 1.1%); secondary endovascular procedure (4.2%, 10.1%, 8.5%); secondary endovascular procedure to correct type I/III endoleak (0%, 1.3%, 3%); and stent graft migration (0% for all three groups).

In Medtronic’s press release, Prof. Verhagen commented, “The Endurant stent graft has opened up standard EVAR to patients who were previously considered ineligible, and the ENGAGE results support the usage of this device in patients with short necks (10 mm and up). The data also show that the Endurant stent graft successfully broadens patient eligibility for standard EVAR.”

The PANDORA study was designed to evaluate the long-term clinical performance of the Endurant stent graft in an all-comer patient population. The study prospectively enrolled 277 consecutive AAA patients, with no exclusion criteria, from November 2007 to December 2010. It is the first independent study of the Endurant stent graft to report long-term results, noted Medtronic.

Baseline characteristics included short neck lengths (49%), symptomatic aneurysms (7%), and ruptured aneurysms (2%). Follow-up compliance approached 99%, with four patients lost to follow-up; 273 patients were included in the analysis. Medtronic reported that despite the complexity of the patients enrolled, PANDORA met its primary endpoint, with a 9.5% AAA-related reintervention rate during follow-up (median, 42.1 months). Kaplan-Meier estimates demonstrated 87% freedom from secondary intervention at 5 years. On the secondary endpoints, there was no (0%) proximal migration of the stent graft, a 2% rate of type I/III endoleaks, and one AAA-related death (0.3%).

“The findings of this independently executed study are consistent with those published from ENGAGE, the largest contemporary postmarket study on a single stent graft,” commented Prof. Torsello in Medtronic’s press release. “The long-term data reinforce the clinical leadership of the Endurant stent graft in an all-comer patient population.”