Abstract and Introduction
Abstract
Silent Cerebral Events/Lesions Related to AF Ablation. Brain magnetic resonance imaging (MRI) has identified a high incidence of cerebral ischemia in asymptomatic patients after atrial fibrillation (AF) ablation (silent). Detection of cerebral ischemic events on MRI is based on acute hyperintense lesions on diffusion-weighted imaging. In the literature, the incidence is related to specifications of MRI and depends on the definition applied. In comparative studies, silent cerebral events (SCE, diffusion-weighted MRI [DWI] positive only) appear to be approximately 3 times more common compared to using a definition of silent cerebral lesions (SCL; without fluid attenuated inverse recovery sequence [FLAIR] positivity). Whereas the FLAIR sequence may turn positive within days after the ischemic event, SCE definition is highly sensitive for early phases of ischemic brain damage. SCE/SCL appear to represent cerebral ischemic infarcts and determine the "embolic fingerprint" of a specific ablation technology and strategy used. The optimum time point for detecting SCE is early after AF ablation (24–72 hours), whereas detection of SCL can only be performed within the first 2–7 days (due to delay of FLAIR positivity). Different technology-, procedure-, and patient-related parameters have been identified to play a role in the multifactorial genesis of SCE/SCL. In recent years, evidence has been gathered that there may be differences of SCE/SCL rates depending upon the ablation technology used, but small patient numbers and a large number of potential confounders hamper all studies. As major findings of recent studies, mode of periprocedural and intraprocedural anticoagulation has been identified as a major predictor for incidences of SCE/SCL. Whereas procedural characteristics related to higher SCE/SCL-rates may be modified, unchangeable patient-related factors should be taken into account for future individualized risk assessment. Novel ablation devices introduced into the market should be tested for their potential embolic fingerprint and refinements of ablation procedures to reduce their embolic potential should be prompted. The knowledge of "best practice" in terms of low SCE/SCL rates has prompted changes in work-flow, which have been implemented into ablation procedures using novel ablation devices. So far, no study has linked SCE/SCL to neuropsychological decline and the low number of AF-ablation-associated events needs to be weighted against the multitude of preexisting asymptomatic MRI-detected brain lesions related to the course of AF itself. Future studies are needed to evaluate if more white matter hyperintensities due to AF may be prevented by AF ablation (producing only a small number of SCE/SCL).
Introduction
Catheter ablation (CA) has been identified as an effective and safe treatment option for patients with symptomatic atrial fibrillation (AF). Whereas efficacy appears to depend upon operator experience and strategy used, complication rates are around 2–5%. Procedure-associated stroke, as the most severe disabling complication, is rare and occurs in less than 1% of cases. Novel periprocedural anticoagulation strategies have further reduced the clinical incidence of cerebral ischemic events.[1–4]
Recent studies have identified symptomatic stroke to be only a minority of cerebral ischemic events as postablation brain magnetic resonance imaging (MRI) identified new ischemic lesions in up to 50% of cases.[5–8] Positive MRI findings may occur in patients without apparent neurological deficit and are therefore classified as "asymptomatic" or "silent." Because further and more elaborated neuro- or psychoneurological testing may reveal potential deficits, the authors prefer the term "silent."
Strategies to further reduce the incidence of periprocedural stroke are limited by the overall low incidence. In clinical studies, the ratio of silent to overt cerebral ischemia is approximately 100:1. Incidence of silent cerebral events (SCE) or silent cerebral lesions (SCL) may be an indirect indicator for the embolic potential of a specific ablation strategy and therefore warrants further evaluation.
SCE are not unique to AF ablation but have been identified after nearly any cardiovascular interventions, including coronary angiography in 15%,[2,5,6,8–16] valve surgery in 42% (including 2 studies with overall 67 patients), and both on- and off-pump coronary artery bypass grafting in 22% (including 8 studies with overall 284 patients).[5,7,17,18]
As a consequence, SCE or SCL have been termed the "embolic fingerprint" of a specific cardiovascular intervention.[8,11,13,16,19] Different from a specific fingerprint, though, the embolic profile of a specific technology may be changed with modifications of the technology or procedural steps.
In this manuscript, authors of different working groups have agreed on a "consensus" statement in regard to SCE/SCL related to CA of AF. Whereas definitive scientific evidence from large-scale studies is still scarce, the present manuscript relies on smaller scientific studies and evidence generated from these. Further improvement in imaging modalities and consensus on the definition of SCE/SCL will further prompt our knowledge about this "complication" of AF ablation.
J Cardiovasc Electrophysiol. 2015;26(4):455-463. © 2015 Blackwell Publishing