One-year results of the multilayer flow modulator stent in the management of thoracoabdominal aortic aneurysms and type B dissections

Purpose: To report 1-year results from the first subgroup of patients treated with the Multilayer Flow Modulator (MFM) stent for aortic aneurysm and dissection. Methods: Up to December 2012, 243 patients have been treated worldwide for aortic aneurysm and dissection with the Cardiatis MFM under the established indications for use. This retrospective review encompasses the first 55 of these patients (41 men; mean age 64.5±18 years), who were treated on a compassionate basis in 11 countries. There were 31 thoracoabdominal aortic aneurysms (8 Crawford type I, 3 type II, 9 type III, and 11 type IV), 7 arch aneurysms, 3 infrarenal abdominal aortic aneurysms, 8 suprarenal aortic aneurysms, and 6 type B dissections. Mean aneurysm diameter was 6.04±1.66 cm, and the mean length was 11.58±7.62 cm. The primary endpoint at 1 year was a composite of rupture and aneurysm-related death. The secondary endpoints were all-cause mortality, visceral branch occlusion, adverse events (i.e., stroke and paraplegia), and reintervention. Results: Technical success was 98.2%; there was no paraplegia or perioperative visceral or renal insult. The mean number of side branches covered was 3.7±1.3 per case (range 0-6); 108 stents were deployed (range 1-5). At 1 year, aneurysm-related survival was 93.7%, all-cause survival was 84.8%, intervention-free survival was 92.4%, and all of the 202 side branches were patent. There were no stent fractures. At 6 months, the mean rate of sac volume increase was 0.36% per month, resulting in a mean volume increase of 2.14%. At 12 months, the rate of increase had slowed to 0.28% per month, resulting in a total average increase in sac volume of 3.26%. The ratio of thrombus to total volume stayed almost constant over the 12 months at 0.48, while the ratio of flow to total volume fell from 0.21 to 0.12 at 12 months. Conclusion: MFM implantation instigates a process of aortic remodeling involving initial thrombus deposition, which slowed between 6 and 12 months. Increasing sac size did not herald rupture, and the MFM was not associated with loss of native side branches. With physiological modulation of the aneurysm, the MFM offers promise for resolution of complex thoracoabdominal pathology with off-the-shelf availability, but this disruptive technology requires further development and technical refinement. Long-term follow-up of the registry patients is mandatory before establishing a randomized controlled study.