Gurmeen Kaur, MBBS
Cardiovascular procedures including Aortic Valve Replacement (AVR), coronary artery bypass grafting (CABG), and cardiac and cerebral catheterization have been associated with increased prevalence of peri-procedural acute ischemic brain lesions on magnetic resonance imaging (MRI).
In this systematic review, Cho et al compared the ratio of radiographic brain infarcts (RBI) to strokes and transient ischemic attacks across cardiac and vascular procedures. RBIs are common after invasive vascular procedures and are encountered a lot more frequently than clinical strokes or TIAs. Literature suggests that peri-procedural ischemic events might serve as a potential surrogate marker for optimizing invasive procedures, which is why an effort was made to compare the rates of RBIs to clinical events.
After extensive review of 6332 citations from MEDLINE and 5 other databases, 29 studies with a total of 2124 subjects were selected. The inclusion criteria included patients who had AVR (surgical or transcatheter), CABG, coronary or cerebral diagnostic angiograms and had an MRI performed systematically pre- and post-procedure along with a post-procedure clinical neurological examination. Cardiac catheterizations were excluded, as were acute stroke thrombectomies. The authors calculated a symptomatic rate ratio (RR), such that RR=(stroke+TIA) rate/RBI rate.
Among the 29 studies, there were 17 cohorts in AVR, 4 cohorts in CABG, 10 cohorts in cardiac catheterization, and 8 cohorts in cerebral angiogram. Mean post-procedure time to MRI was 2 days. Across all study groups, the overall symptomatic RR was 0.10 and did not differ across different procedure categories. In other words, 1 of 10 people with peri-procedural RBIs during cardiovascular procedures resulted in clinical brain infarcts. In a meta-analysis of all AVRs, 69.4% (95% CI, 57.6%–81.4%) had infarcts on MRI, whereas 3.6% had clinical strokes or TIAs with an RR of 0.08. Both clinical brain infarct and RBI rates did not differ between SAVR and TAVR. The rate of clinical events in both low and high risk cardiac angiograms, as well as cerebral angiograms, was very low (0.6%).
The study concluded that symptomatic RR is consistent across all cardiovascular procedures included, and has a low heterogeneity among procedure types, as well as year of study. The paper proposes the use of the symptomatic RR as a procedural safety marker, using MRIs, and as a predictor of risk for peri-procedural ischemic embolic events. With an increasing number of minimally invasive cardiac and cerebral procedures like Balloon Aortic Valvuloplasty and carotid stenting, it will be interesting to monitor the ratio of symptomatic and clinically silent infarcts in the years to come!