High Energy Transcatheter Cardioversion for Chronic, Poorly Tolerated Atrial Fibrillation

Between August 1991 and May 1993, 14 patients affected by chronic, poorly tolerated atrial fibrillation (AF) were submitted to high energy transcatheter Cardioversion. Mean duration of AF was 27.4 ± 45.1 months. In nine patients (56%), AF lasted for > 1 year. All patients had underlying heart disease, with a mean LVEF of 45.2%± 11.8% and a NYHA Class ≥ II. Previously, a mean of 2.9 ± 1.3 patients failed external electrical Cardioversion, with and without antiarrhythmics, have been attempted. Transcatheter conversion was performed by pulling the His-bundle catheter back in the right atrial cavity until no His bundle activity was recorded on distal poles, and then delivering the shock between a proximal electrode (cathode) and a back plate (anode). In all patients, transcatheter conversion restored sinus rhythm. Transient complete atrioventricular (AV) block was observed in four patients (28%), and treated by prophylactic temporary pacing. At 1 year, seven patients (50%) were still in sinus rhythm. In this series, only younger age could be related to AF recurrence (46.1 ± 10.8 vs 63.4 ± 6.8 years, P ≤ 0.004), even if prophylaxis with amiodarone showed a positive trend versus sinus rhythm maintenance (71 % vs 14%, P = NS). In conclusion, high energy transcatheter Cardioversion is a safe and effective method of restoring sinus rhythm in patients with chronic, poorly tolerated AF. In these patients, high energy transcatheter Cardioversion could be considered as an alternative to AV node ablation techniques, avoiding pacemaker implant and embolic risk. Larger studies are needed to determine better patient selection and delineate drug strategy after the procedure.     

Silent Cerebral Events/Lesions Related to Atrial Fibrillation Ablation: A Clinical Review

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).     

Comparison of ThermoCool® Surround Flow Catheter Versus ThermoCool® Catheter in Achieving Persistent Electrical Isolation of Pulmonary Veins: A Pilot Study

Persistent Electrical Isolation of Pulmonary Veins . Introduction: Aim of this study was to compare efficacy and safety of the new ThermoCool Surround Flow® catheter (SFc) versus the ThermoCool® (TCc) in achieving persistent circumferential electrical isolation of the pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF). Methods and Results: This multicenter, randomized, controlled study enrolled patients suffering from paroxysmal AF. Randomization was run in a one‐to‐one fashion between radiofrequency ablation by TCc or SFc. Aim of PVs ablation was documentation of electrical isolation with exit/entrance block recorded on a circular catheter. Among the 106 enrolled patients, 52 (49.0%) were randomized to TCc and 54 (51.0%) to SFc. Total volume of infused saline solution during the procedure was lower in the SFc than in TCc group (752.7 ± 268.6 mL vs 1,165.9 ± 436.2 mL, P < 0.0001). Number of identified and isolated PVs was similar in the 2 groups. Number of PVs remaining isolated 30 minutes after ablation was higher in the SFc than in TCc group (95.2% vs 90.5%, P < 0.03), mainly driven by acute ablation result in the left PVs (96.1% vs 89.7%, P < 0.04). Complications were seldom and observed only in the TCc group (0% vs 3.84%, P < 0.03). At 6‐month follow‐up SFc patients reported a trend toward less AF recurrences compared to those in the TCc group (22.9% vs 27.0%, P = 0.69). Conclusion: PV isolation by SFc lowered the rate of left PV early reconnections and reduced the volume of infused saline solution while maintaining the safety profile of AF ablation. (J Cardiovasc Electrophysiol, Vol. 24, pp. 269‐273, March 2013)     

Long‐Term Results of Transcatheter Atrial Fibrillation Ablation in Patients with Impaired Left Ventricular Systolic Function

AF Ablation and Impaired Left Ventricular Function. Introduction: Long‐term outcome of AF ablation in patients with impaired LVEF is unknown. The aim of this study is to evaluate sinus rhythm (SR) maintenance, clinical status, and echocardiographic parameters over a long‐term period following atrial fibrillation (AF) transcatheter ablation in patients with left ventricular ejection fraction (LVEF) <50%. Methods and Results: A total of 196 patients (87.2% males, age 60.5 ± 10.2 years) with LVEF <50% underwent radiofrequency transcatheter ablation for paroxysmal (22.4%) or persistent (77.6%) AF. Patients were followed up for 46.2 (16.4–63.5) months regarding AF recurrences, functional class, and echocardiographic parameters. All patients underwent pulmonary vein isolation, while 167 (85.2%) required additional atrial lesions. Eleven (5.6%) patients suffered procedural complications. During follow‐up, 58 (29.6%) patients required repeated ablations. At the follow‐up end, 15 (7.7%) patients died, while 74 (37.8%) documented at least one episode of AF, atrial flutter, or atrial ectopic tachycardia. Eighty‐three (47.2%) patients maintained antiarrhythmic drugs. During follow‐up, NYHA class improved by at least one class more frequently among patients maintaining SR compared to those experiencing relapses (70.6% vs 47.9%, P = 0.003). LVEF showed a broader relative increase in patients maintaining SR (32.7% vs 21.4%; P = 0.047) and mitral regurgitation grading significantly decreased (P <0.001) only within these patients. At multivariable analysis SR maintenance emerged as an independent predictor (odds ratio 4.26, 95% CI 1.69–10.74, P = 0.002) of long‐term clinical improvement (reduction in NYHA class ≥1 and relative increase in LVEF ≥10%). Conclusions: Although not substantially worse than in patients with preserved LVEF, AF ablation in patients with impaired LVEF is affected by high long‐term recurrence rate. Among these patients SR maintenance is associated with greater clinical improvement. (J Cardiovasc Electrophysiol, Vol. 24, pp. 24‐32, January 2013)     

Use and Misuse of Multivariable Approaches in Interventional Cardiology Studies on Drug‐Eluting Stents: A Systematic Review

Aims: Randomized clinical trials (RCTs) are the most reliable evidence, even if they require important resource and logistic efforts. Large, cost‐free and real‐world datasets may be easily accessed yielding to observational studies, but such analyses often lead to problematic results in the absence of careful methods, especially from a statistic point of view. We aimed to appraise the performance of current multivariable approaches in the estimation of causal treatment and effects in studies focusing on drug‐eluting stents (DES). Methods and Results: Pertinent studies published in the literature were searched, selected, abstracted, and appraised for quality and validity features. Six studies with a logistic regression were included, all of them reporting more than 10 events for covariates and different length of follow‐up, with an overall low risk of bias. Most of the 15 studies with a Cox proportional hazard analysis had a different follow‐up, with less than 10 events for covariates, yielding an overall low or moderate risk of bias. Sixteen studies with propensity score were included: the most frequent method for variable selection was logistic regression, with underlying differences in follow‐up and less than 10 events for covariate in most of them. Most frequently, calibration appraisal was not reported in the studies, on the contrary of discrimination appraisal, which was more frequently performed. In seventeen studies with propensity and matching, the latter was most commonly performed with a nearest neighbor‐matching algorithm yet without appraisal in most of the studies of calibration or discrimination. Balance was evaluated in 46% of the studies, being obtained for all variables in 48% of them. Conclusions: Better exploitation and methodological appraisal of multivariable analysis is needed to improve the clinical and research impact and reliability of nonrandomized studies. (J Interven Cardiol 2012;25:611–621)     

NEURONOTOXICITY OF AXONALLY TRANSPORTED TOXIC LECTINS, ABRIN, MODECCIN AND VOLKENSIN IN RAT PERIPHERAL NERVOUS SYSTEM

In an attempt to find new and more useful suicide transport agents, the cytotoxic lectins abrin, modeccin and volkensin were pressure microinjected into peripheral nerves (vagus, hypoglossal and sciatic) of adult rats. After 33 h-5 days survival, the brainstems, spinal cords and corresponding sensory ganglia were examined histologically. All three lectins produced profound chromatolysis, and destruction of sensory and motor neurons projecting axons through the injected nerves. Volkensin and modeccin were significantly more potent than any previously reported suicide transport agent. It is concluded that abrin, modeccin and volkensin are effective, unselective suicide transport agents in the rat peripheral nervous system but none is clearly superior to ricin for making restricted sensory and motor neuron ablations. However, modeccin and volkensin are fundamentally different from any previously reported suicide transport agents with respect to spread within the CNS which destroyed neurons adjacent to those initially taking up and transporting the toxin. Possibly this is due to the different oligosaccharide binding specificity of modeccin and volkensin compared to other suicide transport agents. Modeccin and/or volkensin may prove useful in making lesions of CNS interneurons using the suicide transport strategy.