Cerebral Embolic Protection During SAVR Reduced Size, But Not Number of Brain Infarcts
Two different embolic protection devices were successful in capturing debris during surgical aortic valve replacement (SAVR) but did not significantly reduce the overall number of brain infarcts compared with the standard surgical procedure, according to research presented March 19 at ACC.17 in Washington, DC. The study was terminated early after an interim analysis concluded that it was not likely to meet its primary endpoint and it was futile to enroll more patients.
Michael Mack, MD, FACC, et al., evaluated the Embol-X and CardioGard devices, both approved by the U.S. Food and Drug Administration, against the standard aortic cannula in 383 patients (average age 74 years, about 40 percent women) who were randomized at 18 sites in North America. The primary endpoint of freedom from central nervous system infarcts measured clinically or with diffusion-weighted MRI (DW-MRI) at seven days after surgery was similar across the groups; 27.1 percent with Embol-X, 32.7 percent with CardioGard and 34.8 percent with the standard cannula.
Most infarcts were only detectable on the post-op DW-MRI, and <10 percent of patients had clinical symptoms. The investigators also noted that the patients treated with either of the embolic protection devices were less likely to have a larger defect. On DW-MRI, the mean lesion volume was 321.3 mm3 with Embol-X versus 484.4 mm3 with the standard cannula; with CardioGard it was 178.5 mm3 versus 476.4 mm3 with the standard cannula.
The Embol-X device captured nearly all embolic debris (99.1 percent) and the CardioGard device captured 75.8 percent. At day seven after surgery, there was a significant reduction in the rate of in-hospital delirium with the CardioGard device and a trend with the Embol-X device.
The secondary endpoint of clinical stroke at day seven occurred at a similar rate in all three groups. Although there fewer severe strokes through day three with both the embolic protection devices versus the standard cannula, the study was not designed to assess the clinical significance of this observed trend.
At ninety days, overall neurocognitive decline was similar in each of the study arms. But, with the Embol-X device the decline in executive function was reduced compared with the other approaches. At baseline, about 25 percent of patients had mild deficits in executive function and/or short-term memory relative to a standardized population. Of note, there was an increase in acute kidney injury with the Embol-X device.
"There is suggestive evidence that there may be a benefit, despite not meeting the primary endpoint of this trial," Mack said of the embolic devices. It was noted that the trial was not large enough to definitively detect differences in the incidence of clinical stroke, which was analyzed as a secondary outcome, and that DW-MRI is an overly sensitive tool for measuring damage to the brain, hampering the ability of the researchers to distinguish between blood vessel blockages that cause actual neurological deficits from those that do not.
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