Deborah Brauser

April 17, 2017

WASHINGTON, DC — The rate of new subclinical cerebral microbleeds (CMBs) associated with transcatheter aortic-valve replacement (TAVR) can be "quite high," affecting 6-month neurological outcomes, say investigators of new imaging research[1].

The observational study of 84 high-surgical-risk patients with aortic stenosis showed that 26% had one or more CMBs before undergoing TAVR, as measured by cerebral MRI. But 23% of the total participants had at least one new CMB 3 days after the procedure.

In addition, having that kind of brain bleed was significantly associated with worse neurologic scores at baseline (P=0.01) and at the 6-month follow-up (P=0.008).

Significant predictors for a new CMB occurrence during TAVR included a prolonged fluoroscopy time and persistence of acquired von Willebrand disease.

Coinvestigator Dr Eric Van Belle (Heart Institute, Centre Hospitalier Régional Universitaire [CHRU], Lille, France) told attendees at the American College of Cardiology (ACC) 2017 Scientific Sessions that the long-term clinical impact of the findings "will need to be further clarified," such as in MRI substudies.

"We'll also need dedicated studies to better understand the interaction between acquired von Willebrand disease and anticoagulation in this very peculiar population," he added.

Session chair and ACC 2017 vice chair Dr Andrew Kates (Washington University School of Medicine, St Louis, MO) told heartwire from Medscape that the main takeaways are the importance of long-term monitoring and of reaching out to others.

"At today's session, we had cardiac surgeons, cardiologists, and neurologists. The importance of having a multidisciplinary approach for these patients is becoming clear," said Kates.

Silent CMB Factors

The investigators enrolled 90 patients, of whom 84 had full imaging data. All of the 84 (50% men; mean age 80.6 years; mean body-mass index [BMI] 27.9; 4% with a history of bleeding) underwent cerebral MRI 3 days before and 3 days after TAVR. Neuroradiologists recorded the location and number of any CMBs found.

Analysis of von Willebrand factor high-molecular-weight (HMW) multimers were also assessed at the same two time points.

In addition, neurological assessments were conducted preprocedure and at 6 months. These included the modified Rankin scale, the EQ-5D scale, and the Mini-Mental State Examination (MMSE).

In the patients who had new postprocedural CMBs, 69% were located in the lobar regions, 19% in the deep regions, and 12% in the infratentorial regions.

Significant predictors for having a new silent CMB included postprocedurally acquired von Willebrand disease (adjusted risk ratio [RR] 1.42; 95% CI 1.08–1.89 for every lower 0.1 unit of HMW-multimer ratio; P=0.004) and a longer fluoroscopy time (RR 1.21; 95% CI 1.01–1.17 for every 5 minutes of time; P=0.04).

There was also a significant association between CMBs and history of bleeding (P=0.01) and balloon postdilation (P=0.03).

The mean baseline score on the MMSE was 28 for the full group and for those who had no preprocedural CMBs, but it was significantly lower (mean 26) for those who had least one microbleed. This same group also was significantly more likely to have a score greater than 1 on the Modified Rankin scale at 6 months (35% vs 12%, respectively).

"Elegant," but Raises Questions

After the session, panelist Dr Athena Poppas (Rhode Island Hospital Division of Cardiology, Providence) called the study "very elegant" and said it shows that careful pre- and postassessment on both MRI and neurologic tests are crucial, "given the complexities of these patients."

But she wondered whether fluoroscopy time could have been reflecting other parameters, such as catheter manipulation or vascular complexity.

During an on-site press briefing, official discussant Dr Alistair Phillips (Cedars-Sinai Medical Center, Los Angeles, CA) noted that it was an important study with important MRI data.

"It shows that there are some procedural issues that are related to patients getting new microbleeds. Coming up with guidelines and working as a team to improve outcomes for these procedures will have an incredible impact on our society," said Phillips.

Panelist Dr David Thaler (Tufts University School of Medicine, Boston, MA) told heartwire that, as a neurologist, he was intrigued by the study but still doesn't understand why the microbleeds were occurring.

"That's why I asked whether the investigators were sure these really were microbleeds rather than calcific emboli, which can look similar on an MRI scan. And I'm not quite sure I ever got an answer to that," said Thaler.

Still, he noted that if there really is an increase in microbleeds after these procedures, "that's something we need to better understand."

Van Belle reports receiving consultant fees/honoraria from Volcano and St Jude Medical. Kates, Phillips, and Thaler have reported no relevant financial relationships. Poppas reports having GE stock.

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