Implantable cardiac pacing systems are a safe and effective treatment for symptomatic irreversible bradycardia. Under the proper indications, cardiac pacing might bring significant clinical benefit. Evidences from literature state that the action of the artificial pacing system, mainly when the ventricular lead is located at the apex of the right ventricle, produces negative effects to cardiac structure (remodeling, dilatation) and function (dissinchrony). Patients with previously compromised left ventricular function would benefit the least with conventional right ventricle apical pacing, and are exposed to the risk of developing higher incidence of morbidity and mortality for heart failure. However, after almost 6 decades of cardiac pacing, just a reduced portion of patients in general would develop these alterations. In this context, there are not completely clear some issues related to cardiac pacing and the development of this cardiomyopathy. Causality relationships among QRS widening with a left bundle branch block morphology, contractility alterations within the left ventricle, and certain substrates or clinical (previous systolic dysfunction, structural heart disease, time from implant) or electrical conditions (QRS duration, percentage of ventricular stimulation) are still subjecte of debate. This review analyses contemporary data regarding this new entity, and discusses alternatives of how to use cardiac pacing in this context, emphasizing cardiac resynchronization therapy.

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391Rev Bras Cir Cardiovasc | Braz J Cardiovasc SurgRev Bras Cir Cardiovasc 2013;28(3):391- 392Rev Bras Cir Cardiovasc | Braz J Cardiovasc Surg Bras Cir Cardiovasc 2013;28(3):391-400 Sussenbach CP, et al. -Unstable angina does not increase mortality in coronary artery bypass graft surgery twenty minutes (if not interrupted by the nitroglycerin), 2) is described as an intense and frank pain and recent onset (less than 1 month), 3) occurs in a crescendo pattern (e.g., more intense, prolonged or frequent than previously), in the absence signs of myocardial necrosis (elevation of cardiac enzymes). On the ohter hand, the European System Risk in Cardiac Operations (EuroSCORE) defines UA as anginal pain at rest that requires treatment with intravenous nitroglycerin to the surgical procedure. For purposes of this study UA was defined as acute coronary syndrome without ST elevation (ACSST) and without enzyme and/or class IV angina [6,7]. RevAccording to current recommendations on UA, taking into account the patient's risk, CABG is indicated in cases of severe injury of the left main coronary artery, threevessel disease with impaired left ventricular function (left ventricular ejection fraction < 0.5 ); two-vessel lesion with involvement of the proximal left anterior descending artery or decreased left ventricular function or provoked ischemia. Life expectancy, associated diseases, symptom severity and amount of viable myocardium at risk are also important factors [5,8,9].

BackgroundRadiofrequency catheter ablation guided by electroanatomical mapping is currently an important therapeutic option for the treatment of atrial fibrillation. The complexity of the procedure, the several techniques used and the diversity of the patients hinder the reproduction of the results and the indication for the procedure. ObjectiveTo evaluate the efficacy and factors associated with recurrence of atrial fibrillation. MethodsProspective cohort study with consecutive patients submitted to atrial fibrillation ablation treatment guided by electroanatomical mapping. The inclusion criteria were as follows: minimum age of 18 years; presence of paroxysmal, persistent or long-standing persistent AF; AF recording on an electrocardiogram, exercise testing or Holter monitoring (duration longer than 15 minutes); presence of symptoms associated with AF episodes; AF refractoriness to, at least, two antiarrhythmic drugs, one of which being amiodarone, or impossibility to use antiarrhythmic drugs. ResultsThe study included 95 patients (age 55 ± 12 years, 84% men, mean CHADS2 = 0.8) who underwent 102 procedures with a median follow-up of 13.4 months. The recurrence-free rate after the procedure was 75.5% after 12 months. Atrial fibrillation recurred as follows: 26.9% of patients with paroxysmal and persistent atrial fibrillation; 45.8% of patients with long-standing persistent atrial fibrillation (p = 0.04). Of the analyzed variables, the increased size of the left atrium has proven to be an independent predictor of atrial fibrillation recurrence after the procedure (HR = 2.58; 95% CI: 1.26-4.89). Complications occurred in 4.9% of the procedures. ConclusionAtrial fibrillation ablation guided by electroanatomical mapping has shown good efficacy. The increase in left atrium size was associated with atrial fibrillation recurrence.