Cerebral microembolism during cardiac catheterization and risk of acute brain injury: a prospective diffusion-weighted magnetic resonance imaging study.

BACKGROUND AND PURPOSE Cerebral microembolism detected by transcranial Doppler occurs systematically during cardiac catheterization, but its clinical relevance remains unknown. Studies suggest that asymptomatic embolic cerebral infarction detectable by diffusion-weighted (DW) MRI might exist after percutaneous cardiac interventions, especially after retrograde catheterization of the aortic valve in patients with valvular aortic stenosis, with a frequency as high as 22% of cases. We investigated the incidence of new ischemic lesions on serial cerebral DW MRI after cardiac catheterization. METHODS This prospective study involved 46 patients with severe aortic valve stenosis. To assess the occurrence of cerebral infarction, all patients underwent cerebral DW MRI and neurological assessment within 24 hours before and 48 hours after cardiac catheterization and retrograde catheterization of the aortic valve. A subgroup was monitored by transcranial power M-mode Doppler during cardiac catheterization to observe cerebral blood flow and track emboli. RESULTS One patient had a focal diffusion abnormality on DW MRI before cardiac catheterization. After catheterization, we detected only 1 additional acute cerebral diffusion abnormality in a single case (2.2%), although cerebral microemboli were detected in all transcranial Doppler-monitored patients during cardiac catheterization, as expected. All patients remained asymptomatic. Based on these results a mid-point incidence of 5.9% (95% CI, 0.01 to 12.5) for abnormalities on DW MRI in asymptomatic cardiac catheterization patients in our center can be assigned. CONCLUSIONS Unsuspected cerebral infarctions can be detected by DW MRI after cardiac catheterization, but this phenomenon remains unfrequent in our series. Further studies are needed to identify factors explaining the discrepancy between these results and those of previous studies.