While using cerebral embolic protection during transcatheter aortic valve implantation (TAVI) seems appealing to reduce the risk of stroke, which has been reported to be higher than in open aortic valve replacement, the challenge of developing practical CEP devices and then designing appropriate trials may be insurmountable, according to a featured expert opinion in the Journal of Thoracic and Cardiovascular Surgery (2017;154;880-3).
Dr. Messé and Dr. Furie reviewed completed trials of five different CEP devices in 630 patients, noting that the trials confirmed the difficulty of “designing a trial that can prove a clinical benefit.” They noted 30-day stroke rates ranged from 4% to 6.7%, although prospective, nonrandomized European registries reported rates of 3.4% to 4.1%, and a large U.S. registry reported a rate of 2.5%. These results suggest “that some neurologic complications are going undetected or underreported in routine clinical practice.”
That may be a function of the different methods the trials used to determine complications. “There are little data to define best practice, but direct comprehensive assessment by a neurologist is likely the most accurate and sensitive method for detecting clinical stroke,” they added.
Another important factor is the timing of the assessment. They pointed out that half of all 30-day stroke events in TAVI are detected within 2 days of the procedure, but mild or transient symptoms can be missed if the only evaluation occurs just before discharge. “Unfortunately, in most studies this is when the neurologic assessment is performed,” Dr. Messé and Dr. Furie wrote. They added that long-term effects of these strokes have not been well studied.
What’s more, many TAVI patients have subclinical ischemic injury that only neuroimaging can detect. “Studies of MRI performed early after TAVI have demonstrated acute infarcts in 68% to 97% of patients,” the stated. While small and multiple, these microinfarcts may not be totally silent. “Additional studies to assess the long-term implications of clinically silent infarcts are clearly needed,” the coauthors said.
They also noted that a trial of stenting vs. endarterectomy for carotid stenosis raises caution about CEP devices (Lancet Neurol. 2010;9:353-62), as patients who had angioplasty and stenting and were treated with a CEP device had higher rates of acute infarct detected on MRI than those who did not have the CEP. Placing the CEP device through a severely stenosed and symptomatic carotid artery may have led to additional cerebral emboli.
“Placing a cerebral protection device in the aorta for a TAVI procedure also could be problematic in the presence of severe aortic arch disease or variant anatomy,” Dr. Messé and Dr. Furie commented. With two large trials of embolic protection in TAVI currently underway, the coauthors said, “the field eagerly awaits these results.”
Dr. Messé has received research support from GlaxoSmithKline and Direct Flow Medical. Both Dr. Messé and Dr. Furie have participated in the National Institutes of Health/National Heart, Lung, and Blood Institute/National Institute of Neurologic Disorders and Stroke–sponsored Cardiothoracic Surgery Network.