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Clinical Significance of Diffusion-Weighted Brain MRI Lesions After TAVR
Quick Takes
- In a patient-level pooled analysis, the number, size, and total volume of acute brain infarction defined by diffusion-weighted magnetic resonance imaging (DW-MRI) all were associated with clinical stroke and stroke disability after TAVR.
- Maximum individual lesion volume and total lesion volume (TLV) had excellent discrimination in identifying stroke, and the risk of stroke was incremental with increasing TLV.
Study Questions:
What is the relationship between diffusion-weighted magnetic resonance imaging (DW-MRI) total lesion number (TLN), individual lesion volume (ILV), and total lesion volume (TLV) with clinical stroke outcomes after transcatheter aortic valve replacement (TAVR)?
Methods:
Patient-level data were pooled from four prospective TAVR embolic protection studies (DEFLECT III, NeuroTAVR, REFLECT I, and REFLECT II) with consistent predischarge DW-MRI acquisition and core laboratory analysis. The primary endpoints were ischemic stroke (including ischemic stroke with hemorrhagic conversion) and disabling ischemic stroke at 30 days. C-statistic was used to determine the best DW-MRI measure associated with clinical stroke.
Results:
A total of 495 of 603 patients undergoing TAVR completed the predischarge DW-MRI. At 30 days, the rate of clinical ischemic stroke was 6.9%. Acute ischemic brain injury was seen in 85% of patients with 5.5 ± 7.3 discrete lesions per patient, mean ILV 78.2 ± 257.1 mm3, and mean TLV 555 ± 1,039 mm3. The C-statistic was 0.84 for TLV, 0.81 for number of lesions, and 0.82 for maximum ILV in predicting ischemic stroke. On the basis of the TLV cut-point defined by receiver operating characteristic (ROC), patients with TLV >500 mm3 (vs. TLV ≤500 mm3) had more ischemic stroke (18.2% vs. 2.3%, p < 0.0001), more disabling strokes (8.8% vs. 0.9%, p < 0.0001), and less complete stroke recovery (44% vs. 62.5%, p = 0.001) at 30 days.
Conclusions:
The number, size, and total volume of acute brain infarction defined by DW-MRI each are associated with clinical ischemic strokes, disabling strokes, and worse stroke recovery in patients undergoing TAVR, and may have value as surrogate outcomes in stroke prevention trials.
Perspective:
Clinically overt stroke, observed in 2-8% of patients undergoing TAVR, is associated with increased morbidity and mortality. Covert or ‘silent’ ischemic brain injury occurs far more often (in 70-100% of patients). This patient-level pooled analysis is the first extensive clinical validation of brain injury defined by DW-MRI as a potential surrogate for clinical stroke. Major study findings are that the number, size, and total volume of DW-MRI–defined acute brain infarction after TAVR were associated with clinical stroke and stroke disability; that maximum ILV and TLV had excellent discrimination in identifying stroke; and that the risk of stroke was incremental with increasing TLV. Potential limitations to the use of DW-MRI include its cost, tolerability, and potential contraindications related to cardiovascular implanted electronic devices.
Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Interventions and Imaging, Magnetic Resonance Imaging
Keywords: Brain Ischemia, Diffusion Magnetic Resonance Imaging, Transcatheter Aortic Valve Replacement
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