Radiofrequency Catheter Ablation of Atrial Fibrillation: A Cause of Silent Thromboembolism?

Abstract

Background-Radiofrequency left atrial catheter ablation has become a routine procedure for treatment of atrial fibrillation. The aim of this study was to assess with preprocedural and postprocedural cerebral magnetic resonance imaging the thromboembolic risk, either silent or clinically manifest, in the context of atrial fibrillation ablation. The secondary end point was the identification of clinical or procedural parameters that correlate with cerebral embolism. Methods and Results-A total of 232 consecutive patients with paroxysmal or persistent atrial fibrillation who were candidates for radiofrequency left atrial catheter ablation were included in the study. Pulmonary vein isolation or pulmonary vein isolation plus linear lesions plus atrial defragmentation with the use of irrigated-tip ablation catheters was performed. All of the patients underwent preprocedural and postablation cerebral magnetic resonance imaging. A periprocedural symptomatic cerebrovascular accident occurred in 1 patient (0.4%). Postprocedural cerebral magnetic resonance imaging was positive for new embolic lesions in 33 patients (14%). No clinical parameters such as age, hypertension, diabetes mellitus, previous history of stroke, type of atrial fibrillation, and preablation antithrombotic treatment showed significant correlation with ischemic cerebral embolism. Procedural parameters such as activated clotting time value and, in particular, electric or pharmacological cardioversion to sinus rhythm correlated with an increased incidence of cerebral embolism. Cardioversion was also associated with an increased risk of 2.75 (95% confidence interval, 1.29 to 5.89; Pϭ0.009). Conclusions-Radiofrequency left atrial catheter ablation carries a low risk of symptomatic cerebral ischemia but is associated with a substantial risk of silent cerebral ischemia detected on magnetic resonance imaging. Independent risk factors for cerebral thromboembolism are the level of activated clotting time and, in particular, the electric or pharmacological cardioversion to sinus rhythm during the procedure. (Circulation. 2010;122:1667-1673.)

2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: Recommendations for Patient Selection, Procedural Techniques, Patient Management and Follow-up, Definitions, Endpoints, and Research Trial Design

“…724,728,1207 The clinical significance of such ACE lesions is not known, and many will resolve to the point of being undetectable after weeks or months. The impact on cognitive function, if any, is not clear.…”

Catheter Ablation of Lone Atrial Fibrillation

“…Symptomatic procedural thromboembolic cerebrovascular complications can be treated by emergency percutaneous intervention with mechanical recanalization of culprit artery or by administration of thrombolytic therapy [3,120]. However, it seems that symptomatic stroke represents only "the top of the ice berg", because cerebral MRI scanning, performed just before and after catheter ablation of AF, detected a disturbing rate of asymptomatic brain embolism of 1.7-38% [148,149]. Fortunately, follow-up MRI obtained several weeks later demonstrated complete regression of these brain lesions.…”

Could it be advantageous to tune the temperature controller during radiofrequency ablation? A feasibility study using theoretical models

“…From a mathematical point of view, the model is based on a coupled electric-thermal problem which was solved using the Bioheat Equation [17]: (1) where T is temperature, t is time, ρ is tissue density, c is specific heat, k is thermal conductivity, q is the heat source produced by RF power, Q p is the heat loss from blood perfusion and Q m is metabolic heat generation. Q p and Q m are insignificant in RF cardiac ablation and thus were not considered [17].…”

“…where T m is the output and U(s) is the input of the dynamic system, A, B 1 and B 2 are the constant values identified, and k S is the system gain. Once the transfer function was obtained, the values of parameters Kp and Ki were calculated by using root locus techniques [19].…”

“…Radiofrequency (RF) catheter ablation is currently used to treat some types of cardiac arrhythmias [1]. This technique uses RF current (≈500 kHz) to produce a thermal lesion and hence tissue necrosis in the target zone causing the arrhythmia.…”