Outcomes after atrioventricular node ablation and biventricular pacing in patients with refractory atrial fibrillation and heart failure: a comparison between non-ischaemic and ischaemic cardiomyopathy.

AIMS: Atrioventricular junction ablation (AVJA) combined with biventricular (BiV) pacing (AVJA/BiV) is an effective treatment for refractory atrial fibrillation (AF) and rapid ventricular response (RVR) associated with heart failure (HF). This study compared the outcomes between patients with non-ischaemic (DCM) and ischaemic cardiomyopathy (ICM) following AVJA/BiV for AF/RVR. METHODS AND RESULTS: This was a retrospective study of 45 patients, comparing the response to AVJA/BiV in patients with ICM to those with DCM. The study compared (a) the change in echocardiographic parameters of HF (ejection fraction (EF) and left ventricular dimensions) prior to, and at least 6 months post AVJA/BiV; and (b) HF hospitalizations (HFH) and appropriate implantable cardioverter defibrillator (ICD) therapies occurring post-procedure. Ejection fraction improved significantly in the DCM group (ΔEF 11.2% ± 11.9; P< 0.01); however, EF remained unchanged (ΔEF 0.5% ± 9.9; P = NS) in the ICM group post-AVJA/BiV. Post-procedurely, HFH were significantly more common (15/18 vs. 4/25; P < 0.0001), and there were significantly more appropriate ICD therapies (9.4 ± 12.3 vs. 2.3 ± 6.1; P = 0.01) in the ICM compared with the DCM group. CONCLUSION: After AVJA/BiV, there was significantly less post-procedural echocardiographic reverse remodelling, and more HFH in the ICM compared with the DCM group. In addition, significantly more appropriate ICD therapies occurred in ICM patients post-procedure. These differences may be due to the presence of more extensive discrete myocardial scar in patients with ICM. Furthermore, it is possible that tachycardia-induced cardiomyopathy plays more of a causative role in HF in patients with AF and DCM than those with ICM.

Embolic complications of direct current cardioversion of atrial arrhythmias: association with low intensity of anticoagulation at the time of cardioversion.

OBJECTIVES: The goal of this study was to identify the factors responsible for embolic complications of direct current (DC) cardioversion of atrial arrhythmias. BACKGROUND: Direct current cardioversion of atrial fibrillation (AF) carries a risk of thromboembolism, which is reduced, but not eliminated, by anticoagulation. The risk of embolism after conversion of atrial flutter is believed to be lower. No series to date has included enough patients receiving anticoagulants or enough patients with atrial flutter to estimate the risk in these groups. METHODS: We reviewed the case records of 1,950 patients who underwent 2,639 attempts at DC cardioversion. RESULTS: Cardioversion was performed within two days of the apparent onset of the arrhythmia in 443 episodes, 352 without subsequent prolonged anticoagulation with one embolic complication. Cardioversion was preceded by warfarin therapy for > or = 3 weeks in 1,932 instances. No embolic complication occurred in 779 attempts performed with an international normalized ratio (INR) of > or = 2.5 (95% confidence limits 0% to 0.48%). Of 756 cases in which the INR was <2.5 or was not measured before conversion, nine were complicated by thromboembolism. Embolism was significantly more common at an INR of 1.5 to 2.4 than at an INR > or = 2.5 (0.93% vs. 0%, p = 0.012). The incidence of embolism after conversion of atrial flutter or tachycardia was similar to that after cardioversion of AF (0.72% vs. 0.46%, p = NS). CONCLUSIONS: The INR should be > or = 2.5 at the time of cardioversion if the duration of AF is uncertain or >2 days. Cardioversion of atrial flutter presents similar risks and requires similar anticoagulation.

Current trends in supraventricular tachycardia management.

BACKGROUND: Supraventricular tachycardia (SVT) is a general term describing a group of arrhythmias whose mechanism involves or is above the atrioventricular node. The mechanisms of most forms of SVT have been elucidated, and pharmacologic and invasive therapies have evolved simultaneously. METHODS: We provide a brief overview of the mechanisms, classifications, and electrocardiographic characteristics of different SVTs and describe current trends in noninvasive and invasive therapies. RESULTS: The term SVT encompasses a heterogeneous group of arrhythmias with different electrophysiologic characteristics. Knowledge of the mechanism of each SVT is important in determining management at the bedside and in the electrophysiology laboratory. CONCLUSION: In the acute setting, vagal maneuvers and pharmacologic therapy can be effective in arrhythmia termination. Catheter-based radiofrequency ablation has revolutionized therapy for many SVTs, and newer techniques have significantly improved ablation efficacy and reduced periprocedural complications and procedure times. Cryoablation is currently being investigated as an alternative form of energy delivery, although the long-term effectiveness of this procedure currently limits its use for many SVTs.

Newer algorithms in bradycardia management.

Permanent cardiac pacemakers (PPM) are effective in the treatment of bradycardia in a growing number of clinical scenarios. An appreciation of the capacity of PPMs to result in negative hemodynamic and proarrhythmic effects has grown alongside clinical experience with permanent pacing. Such experience has necessitated the development of algorithms aimed at optimizing device functionality across a broad spectrum of physiologic and pathologic conditions. This review highlights recent device-based algorithms used in automated threshold testing, reduction of right ventricular pacing, prevention and treatment of pacemaker-mediated tachycardia, mode switching for atrial tachyarrhythmias, rate-modulated pacing, and advances in arrhythmia storage and remote monitoring.

Ablation of left ventricular epicardial outflow tract tachycardia from the distal great cardiac vein.

OBJECTIVES: The purpose of this study was to examine the feasibility and safety of ablation of idiopathic outflow tract ventricular tachycardia (OTVT) from the distal ramifications of the coronary sinus (CS). BACKGROUND: A significant minority of patients presenting with idiopathic OTVT have an epicardial focus, the standard approach to which involves ablation from within one of the aortic valve cusps (AVCs). We describe the successful ablation of idiopathic epicardial OTVT from within the CS in the distal great cardiac vein (GCV). METHODS: Ablation from the distal GCV was performed in 5 patients with idiopathic OTVT who had unfavorable mapping, in some cases unsuccessful ablation from various endocardial and epicardial sites including the AVCs, and in 1 patient via the direct epicardial approach. An electroanatomic mapping system (Carto) was used in 3 patients, and conventional mapping was performed in 2 patients, and in 3 patients cryothermal ablation was performed. RESULTS: In all patients, the first ablation lesion in the GCV successfully eliminated the arrhythmia. All patients have remained free of VT after a mean follow-up of 24 (7 to 44) months. There were no immediate or long-term complications. CONCLUSIONS: Idiopathic epicardial OTVT can be successfully ablated from the distal GCV, and should be seen as an alternative to ablation from the aortic valve cusps.

Managing the Risk of Sudden Cardiac Death in Nonischemic Patients

Atividade de educação médica continuada onde John Chin (moderador) e Owen A. Obel (palestrante) discorrem sobre o gerenciamento do risco de morte cardíaca súbita em pacientes não isquêmicos. Há a possibilidade de assistir ao vídeo, ler a transcrição das falas com slides e fazer o download do material em formato ppt. Também traz a possibilidade de realizar o teste de educação médica continuada da atividade e informação de como obter créditos pela mesma. Necessário estar cadastrado no site www.theheart.org para acesso ao material.