HOUSTON – An expandable mesh cylinder that is approved to treat large, wide-necked carotid aneurysms has now proved successful in treating small lesions of the internal carotid or vertebral artery up to 12 mm in diameter.

The Pipeline Embolization Device (PED, Medtronic) completely occluded 84% of such lesions without significant stenosis or retreatment within 1 year in the PREMIER trial, Ricardo Hanel, MD, PhD, said at the International Stroke Conference sponsored by the American Heart Association.

Overall morbidity and mortality in the year-long trial was very low (2.2%). However, within the first year, three patients had a major stroke in brain regions supplied by the treated artery; one of these was related to device deployment and was fatal, said Dr. Hanel, director of the Baptist Neurological Institute, Jacksonville, Fla.

The PED has been used off-label for small, wide-necked aneurysms since shortly after its 2011 approval, Dr. Hanel said. PREMIER’s success should inspire confidence in both physicians and patients, who face a difficult decision when confronted with this condition. The rupture risk of untreated small, wide-necked aneurysms is small, about 1% per year. Since the lesions are not amenable to coiling, and clipping imposes operative risks that may exceed that of rupture, many simply choose to live with the aneurysm.

Counseling patients with these lesions is not easy, Dr. Hanel said. Treatment decisions must take into account not only the patient’s current clinical status and comorbidities, but family history and personal preference. In fact, patient preference was the largest driver of treatment (63%) in the PREMIER study.

In an interview, Dr. Hanel illustrated the importance of individualized decision making. A middle-aged female had been monitored for a small aneurysm for 7 years. When the patient was 6 years old, her mother died during an open operation to treat an aneurysm.

“We had tried to treat this patient with coiling [when the lesion was first detected], but it was unsuccessful,” Dr. Hanel said. “And since her mother had died during surgery, she did not want to go for an open approach. Now, 6 years later, we have the technology to cure her with a single device, and the odds of [recurrence over 10 years] are virtually zero. It is a very personal decision, and we take a lot of factors under consideration before we decide to expose the patient to the risks of this treatment.”

The PED is a flexible 75% cobalt-chromium/25% platinum-tungsten mesh with a braided configuration. It is advanced slightly beyond the aneurysm neck and then deployed. As it opens, it partially occludes the lesion, immediately decreasing the amount of blood entering the sac. Within a month, vascular remodeling is well underway; as endothelium grows throughout the mesh, blood flow into the aneurysm is gradually cut off. Eventually the aneurysmal sac recedes, and the normal vascular architecture is restored.

“Within 4 weeks you can’t see the metal at all,” Dr. Hanel said. “It’s covered by a thin layer of endothelial cells. This device allows the patient’s body to heal and close the aneurysm, and we don’t have to deal with the reoccurrence problem we have with stent coils. The pipeline treats the entire circumference of the vessel.”

The PED is used in combination with dual-antiplatelet therapy (DAP, aspirin/clopidogrel). Dr. Hanel initiates DAP 7 days before the procedure and continues it for 3 months. At that time, clopidogrel may be discontinued. “I advise my patients to then take a baby aspirin every day for the rest of their lives,” and they are regularly monitored, he said. “Aspirin seems to protect against the formation and rupture of aneurysms.”

PREMIER followed 141 patients with unruptured, wide-necked small aneurysms of the internal carotid (up to the terminus) or the vertebral artery segment up to and including the posterior inferior cerebellar artery. The primary efficacy endpoint was complete aneurysm occlusion and absence of significant parent artery stenosis at 1 year. The secondary endpoint was successful device deployment.

The primary safety endpoint was major stroke in the territory supplied by the treated artery or neurologic death at 1 year. There were two secondary safety endpoints: major stroke or neurologic death within 30 days, attributable to procedural complications, and intracerebral hemorrhage more than 30 days later.

The patients were largely female (88%) with a mean age of 55 years. They were asymptomatic with a mean modified Rankin Scale score of 0.2 and National Institutes of Health Stroke Scale score of 0.1. Nearly half of the patients had hypertension, and 38% had hyperlipidemia. About 28% were current smokers, and another 16% had a history of smoking.

The patients’ mean maximal aneurysm diameter was 4.6 mm, with a mean neck width of 3.7 mm. The majority of lesions (84%) were less than 7 mm in diameter, but they ranged up to 12 mm.

Internal carotid artery aneurysms comprised 95% of all in the study; 5% were in the vertebral artery. Most involved the side wall (84%), while the remainder involved a side branch (12%) or were fusiform (4%).

There was only one unsuccessful initial deployment, resulting in a 99.3% deployment success rate. The mean procedure time was 78 minutes. While most patients received just one PED, 10 received multiple devices. The PED completely covered the entire neck of the lesion in 97%. There were no intraoperative aneurysm ruptures and no intraoperative deaths.

At 1 year after implantation, 84% of the aneurysms were completely occluded, with the aneurysmal sac eliminated in 92%. A residual aneurysm remained in 11 patients (8%), and a residual neck in 8 patients (6%). Two patients (1.4%) had arterial stenosis of more than 50%. Three patients (2.2%) required retreatment.

There were three major strokes in the region supplied by the target artery in three patients.

The fatal stroke occurred in a patient who had an aneurysm on the right ophthalmic carotid segment. The first device failed to deploy correctly and was removed. A second device was implanted. The next day the patient developed a facial droop, slurred speech, and a headache. She experienced a distal intraparenchymal hemorrhage and underwent hemicraniotomy, but did not survive.

The second stroke occurred in a patient who needed two devices to occlude a lesion in the left ophthalmic segment of the carotid. The patient developed an intraparenchymal hemorrhage on postoperative day 15. The stroke resolved with sequelae and the clopidogrel dose was increased.

The third stroke was associated with treatment of a right communicating segment aneurysm. The patient stopped taking the recommended DAP and experienced an acute ischemic stroke 169 days after the procedure. This stroke also resolved with sequelae.

Based on the results of PREMIER, Medtronic will pursue Food and Drug Administration approval of the PED for small to medium wide-necked aneurysms, Dr. Hanel noted.

Medtronic sponsored the study. Dr. Hanel is an adviser to the company and has received research funds from it.

msullivan@frontlinemedcom.com

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Mesh cylinder effective for small to medium wide-necked aneurysms