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Abnormal Brain Imaging Results After TAVR: Never a Good Sign

Issue: May/June 2016

ByDavid R. Holmes Jr., MD

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Cardiac procedures, including CABG, surgical aortic valve replacement, transcatheter aortic valve replacement, atrial fibrillation ablation, patent foramen ovale closure and left atrial appendage occlusion procedures — and even simple diagnostic angiograms — may lead to potential serious neurological risks. It is believed that brain damage detected using advanced MRI techniques after virtually all cardiac procedures — both transcutaneous and surgical — occurs in at least 20% of cases and is most common after aortic valve replacement.

Brain damage after TAVR is grossly underreported and underdiagnosed. The recent NeuroTAVR study, presented by Lansky and colleagues at London Valves 2015, is the first U.S. study to explore damage to the brain after TAVR procedures. There have been numerous European studies focused on this concern. Abnormal brain imaging can never be regarded as a positive finding.

Available Research

The NeuroTAVR study, which was conducted out of Yale University, showed that 94% of patients (n = 44) had new lesions in the brain after a TAVR procedure and 30% to 50% of patients had declining neurocognition scores at 30 days when compared with pre-TAVR scores. Additionally, Montreal Cognitive Assessment scores, a widely accepted assessment of attention and concentration, executive functions, memory, language, conceptual thinking, calculations and orientation, become worse in 33.5% of patients at discharge and in 40.6% of patients at 30 days. Also, stroke rates at discharge were 22.6% according to American Heart Association/American Stroke Association stroke definitions and 6.8% according to the Valve Academic Research Consortium-2 (VARC-2) criteria. At 30 days postdischarge, rates were 14.8% per AHA/ASA stroke definitions and 6.8% per VARC-2 criteria.

In other earlier studies, stroke rates of 20% to 25% by AHA/ASA definitions have been reported after surgical AVR and TAVR performed using third-generation valves, including Sapien 3 (Edwards Lifesciences).

Supporting this are nearly a dozen studies from Europe that explore central nervous system damage by diffusion-weighted MRI after TAVR, reporting that 58% to 100% of patients have new brain lesions.

These results are in sharp contrast to other recent valve studies, which report a perioperative incidence of stroke after TAVR of about 1%, and confine the definition of stroke to “disabling stroke,” focusing on the most immediate and devastating neurological outcomes. These studies, including PARTNER 2, therefore end up overlooking important potential detrimental cerebral damage and do not report all ischemic strokes, as they did not routinely include brain imaging or neurological/neurocognitive assessment. Any level of lesion has the ability to negatively affect the patient’s daily life.

Additionally, the potential long-term effect has not been fully researched, and the long-term role of these abnormalities in neurocognitive brain disorders is the focus of intense interest. The lesions may be additive as patients undergo additional invasive procedures during their life. Prospective trials in a variety of subset of procedures such as AF ablation and TAVR will be valuable, and longer-term follow-up of patients in these trials is critical to ascertaining the full scope of the problem.

Stroke Prevention

There is a growing body of evidence indicating that cerebral embolic protection devices significantly reduce cerebral lesions after TAVR. The most recent study, DEFLECT III, found a reduction of postoperative neurological symptoms at discharge for patients undergoing TAVR (n = 85) through the use of the TriGuard device (Keystone Heart) compared with patients who did not receive the device (15.4% vs. 3.1%). With TriGuard protection, complete freedom from ischemic brain lesions was 46% higher in the intention-to-treat analysis (21.2%) and 57% higher in the per-treatment analysis (26.9%) compared with controls (11.5%).

In the CLEAN TAVI study, which was performed using the Claret Sentinel device in 100 patients undergoing an endovascular aortic valve prosthesis implant procedure through the femoral artery, results demonstrated a 28% vs. 16% reduction in postoperative neurological symptoms, and a reduction in new brain lesion number and volume.

In Europe, brain-protection deflectors are being used successfully in several hospitals and the number of new sites is increasing rapidly. In the United States, it is clear that we need to determine ways to avoid the brain injury that we have seen identified by diffusion-weighted MRI.

Future Steps

Concerns of neurologic damage after TAVR must be met head-on with existing and new technologies.

The first step is to look for new neurological postprocedure deficits in a thorough and comprehensive manner, including assessment of the long-term ramifications of the abnormalities identified immediately after the procedures.

The second step is to validate and then integrate neuroprotective technologies with an acceptable risk–benefit profile that have the potential to prevent or minimize brain injury, and use these technologies more routinely.

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• For more information:
• David R. Holmes Jr., MD, is professor of medicine at the Mayo Clinic College of Medicine and a consultant in the division of cardiovascular diseases and the department of internal medicine at Mayo Clinic in Rochester, Minnesota. Holmes is a member of the Intervention section of the Cardiology Today Editorial Board.

Disclosure: Holmes reports no relevant financial disclosures.