Francisco Costa

Left atrial volume is more important than the type of atrial fibrillation in predicting the long-term success of catheter ablation

BACKGROUNDnThe type of atrial fibrillation (AF) is the sole prognostic factor that affects the level of recommendation for catheter ablation in the current guidelines. Despite being recognized as a predictor of recurrence, relatively little emphasis is given to left atrium (LA) size. The aim of this study was to assess the relative importance of LA volume and type of AF as predictors of outcome after PVI.nnnMETHODSnWe assessed 809 consecutive patients with symptomatic drug-refractory AF (584 male, mean age 57 ± 11 years) undergoing 905 percutaneous PVI procedures in two centers. LA volume was assessed by cardiac CT and/or electroanatomical mapping prior to AF ablation. The study endpoint was symptomatic and/or documented AF recurrence.nnnRESULTSnThe majority of patients (73.2%, n=592) had paroxysmal AF. The mean indexed LA volume was 55 ± 20 ml/m(2). During a follow-up of 2.4 ± 1.7 years, there were 280 recurrences. The relapse rate of patients with paroxysmal AF in the highest tertile of LA volume was higher than the relapse rate of patients with non-paroxysmal AF in the lowest tertile (20.0% vs. 10.9% per person-year, respectively, p=0.041). LA volume (HR 1.16 for each 10 ml/m(2), 95% CI 1.09-1.23, p<0.001), female gender (HR 1.55, 95% CI 1.19-2.03, p=0.001), and non-paroxysmal AF (HR 1.31, 95% CI 1.01-1.69, p=0.039) were the only independent predictors of AF recurrence. Split-sample cross-validation resampling confirmed LA volume as the strongest predictor of relapse after PVI.nnnCONCLUSIONnLeft atrial volume seems to be more important than the type of atrial fibrillation in predicting the long-term success of pulmonary vein isolation.

MRI-conditional pacemakers: current perspectives

Use of both magnetic resonance imaging (MRI) and pacing devices has undergone remarkable growth in recent years, and it is estimated that the majority of patients with pacemakers will need an MRI during their lifetime. These investigations will generally be denied due to the potentially dangerous interactions between cardiac devices and the magnetic fields and radio frequency energy used in MRI. Despite the increasing reports of uneventful scanning in selected patients with conventional pacemakers under close surveillance, MRI is still contraindicated in those circumstances and cannot be considered a routine procedure. These limitations prompted a series of modifications in generator and lead engineering, designed to minimize interactions that could compromise device function and patient safety. The resulting MRI-conditional pacemakers were first introduced in 2008 and the clinical experience gathered so far supports their safety in the MRI environment if certain conditions are fulfilled. With this technology, new questions and controversies arise regarding patient selection, clinical impact, and cost-effectiveness. In this review, we discuss the potential risks of MRI in patients with electronic cardiac devices and present updated information regarding the features of MRI-conditional pacemakers and the clinical experience with currently available models. Finally, we provide some guidance on how to scan patients who have these devices and discuss future directions in the field.

Ablação epicárdica percutânea em arritmias ventriculares

INTRODUCTIONnReentrant circuits of ventricular tachycardia may involve not only the endocardium but also the epicardium. Epicardial ablation can be useful in these situations.nnnOBJECTIVEnThe aim of this study was to assess efficacy, safety and complications in a series of consecutive patients who underwent ablation of ventricular tachycardia with epicardial mapping.nnnMETHODSnThe study included all patients undergoing ventricular tachycardia ablation with epicardial mapping from 2004 to 2012. Of a total of 95 ablations, an epicardial approach was attempted in nine patients, eight male, mean age 58±12 years. Endocardial mapping was performed in all patients previously or simultaneously. The etiology of the arrhythmia was non-ischemic in eight patients and ischemic in one. We compared the number of events in the six months prior to the epicardial procedure and six months after.nnnRESULTSnPercutaneous epicardial access was achieved in eight patients. In one case it was not possible due to the presence of adhesions. In none of the patients was the procedure repeated and there were no major complications during hospitalization. In a mean follow-up of 3.5±1.2 years, one patient suffered stroke; there were no other medium-to-long-term complications and the number of ventricular tachycardia episodes was reduced in all patients after ablation.nnnCONCLUSIONSnEpicardial radiofrequency ablation of ventricular tachycardia was effective in reducing morbidity in eight patients, with a low risk of complications in the short and medium-to-long term.

Cardioversor desfibrilhador implantável subcutâneo – experiência de um centro

BACKGROUNDnImplantable cardioverter-defibrillators (ICDs) are important tools in the prevention of sudden death, but implantation requires transvenous access, which is associated with complications. Subcutaneous implantable cardioverter-defibrillators (S-ICDs) may prevent some of these complications.nnnAIMnTo evaluate the therapeutics and complications associated with S-ICD systems.nnnMETHODSnS-ICD implantation was planned in 23 patients, for whom the indications were vascular access problems, increased risk of infection or young patients with long predicted follow-up. The population consisted of four patients with ischemic heart disease, three of them on hemodialysis (two with subclavian vein thrombosis), five with left ventricular noncompaction, four with Brugada syndrome, three with arrhythmogenic right ventricular cardiomyopathy, one with transposition of the great vessels, two with dilated cardiomyopathy and four with hypertrophic cardiomyopathy.nnnRESULTSnS-ICDs were implanted in 21 patients, two having failed to fulfil the initial screening criteria. Mean implantation time was 77 minutes, with no complications. Defibrillation tests were performed, and in one patient the generator had to be repositioned to obtain an acceptable threshold. In a mean follow-up of 14 months, 10 patients had S-ICD shocks, which were appropriate in half of them; one developed infection, one needed early replacement due to loss of telemetry and one patient died of noncardiac cause.nnnCONCLUSIONSnS-ICD implantation can be performed by cardiologists with a high success rate. Initial experience appears favorable, but further studies are needed with longer follow-up times to assess the safety and efficacy of this strategy compared to conventional devices.