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BRAVO-3 MRI: Silent emboli common after TAVR, may be linked to stroke

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A high rate of clinically silent cerebral embolization exists after transcatheter aortic valve replacement, with intraprocedural anticoagulation choice making no difference, according to results from the BRAVO-3 MRI study presented at EuroPCR.

In the nested, prospective cerebral substudy of the BRAVO-3 trial, researchers evaluated 69 of 178 (38%) patients enrolled at four BRAVO-3 study sites where post-TAVR MRI of the brain was routinely performed. BRAVO-3 was an open-label, randomized controlled trial comparing bivalirudin (Angiomax, The Medicines Company) with unfractionated heparin in high-risk or inoperable patients undergoing TAVR.

Participants in the substudy underwent diffusion-weighted MRI (DW-MRI) of the brain after TAVR and before hospital discharge. The researchers defined recent ischemic lesions as a hypersignal in DW-MRI sequences.

Of the 69 patients in the substudy, 33 were randomly assigned bivalirudin and 36 were randomly assigned unfractionated heparin (UFH). Bivalirudin was administered in an initial bolus dose (0.75 mg/kg), followed immediately by continuous IV infusion (1.75 mg/kg/hour in patients with normal kidney function). UFH was administered in repeated weight-adjusted boluses designed to attain the recommended clotting time of more than 250 seconds. Dosing, as well as the decision to reverse the action of UFH at the end of the procedure, was done based on local criteria.

The primary outcome was the proportion of patients with a minimum of one new cerebral embolus diagnosed on DW-MRI. Researchers also assessed whether different procedural anticoagulation approaches had an effect on rates of post-TAVR cerebral embolizations. Secondary outcomes included total volume of new cerebral emboli per patient, total number of new cerebral emboli per patient, total number of new cerebral emboli in each cerebral hemisphere and patient, and 48-hour and 30-day neurological outcomes.
Of the 69 patients, nine were not included in the final analysis because they could not have a postprocedural MRI.

The researchers found that the TAVR procedure was successful in all patients. Postprocedural MRI found that 61.7% of the patients had at least one new cerebral emboli; this did not differ between the bivalirudin and heparin groups (65.5% vs. 58.1%; P = .55). No difference was seen between groups in the percentage of patients with a large embolus volume (total volume ≥ 1,000 mm³: bivalirudin group, 10.3%; UFH group, 12.9%; P = .76). According to the researchers, no significant difference was seen between the groups in terms of the mean number, total volume, median and maximal volume of each embolus per patient, or percentage of patients with a clinical stroke at 48 hours. All patients who presented with stroke demonstrated signs of new emboli on MRI.

The bivalirudin group’s median number of lesions was one (interquartile range, 0-3) and the UFH group’s was one (interquartile range, 0-1). No statistical difference was seen between groups in the median number of lesions in the right (P = .1) or the left hemisphere of the brain (P = .1), the researchers wrote.

There were no deaths or MIs observed. Compared with UFH, bivalirudin did not yield significant differences in major bleeding (BARC 3b or higher: RR = 0.53; 95% CI, 0.05-5.58) at 48 hours or before discharge. Net adverse clinical events at 30 days also did not differ significantly between groups (RR = 0.46; 95% CI, 0.13-1.61), according to the researchers.

“The BRAVO-3 MRI study confirms the high rate of clinically silent cerebral embolization after TAVR as reported in other trials, without demonstrating any benefit regarding procedural anticoagulation with bivalirudin vs. heparin in reducing these events,” the researchers wrote. “The results introduce a potential link between silent emboli on MRI and postprocedural clinical stroke.” – by Jennifer Byrne

References:

Van Belle E, et al. New Valvular Interventions and Enabling Technologies. Presented at: EuroPCR; May 17-20, 2016; Paris.
Van Belle E, et al. J Am Coll Cardiol. 2016;doi:10.1016/j.jacc.2016.05.006.

Disclosure: The Medicines Company funded the study. Three researchers report being employed by and two researchers report consulting for The Medicines Company.