Catheter ablation for chronic atrial fibrillation

Vein of Marshall ethanol infusion for persistent atrial fibrillation: VENUS and MARS clinical trial design

BACKGROUND

Although pulmonary vein isolation (PVI) is effective in the treatment of paroxysmal atrial fibrillation (AF), its success rates in persistent AF are suboptimal. Ablation strategies to improve outcomes including additional lesions beyond PVI have not consistently shown benefit. Recurrence as perimitral flutter (PMF) is a common form of ablation failure. The vein of Marshall (VOM) contains myocardial connections and abundant sympathetic and parasympathetic innervation implicated in the genesis and maintenance of AF, and is anatomically co-localized with the mitral isthmus, the ablation target of PMF. VOM ethanol infusion is effective in targeting these arrhythmia substrates.

OBJECTIVE

To test the safety and efficacy of VOM ethanol infusion when added to PVI in patients undergoing either de novo ablation of persistent AF or after a previous ablation failure.

STUDY DESIGN

VENUS-AF and MARS-AF are prospective, multicenter, randomized, controlled trials. VENUS-AF will enroll patients undergoing their first catheter ablation of persistent AF. MARS-AF will enroll patients undergoing ablation after previous ablation failure(s). Patients (n = 405) will be randomized to PVI alone or in combination with VOM ethanol infusion. The primary endpoints include procedural safety and freedom from AF or atrial tachycardia (AT) of more than 30 seconds on 30-day continuous event monitors at 6 and 12 months after randomization procedure (single-procedure success), off antiarrhythmic drugs. Key secondary endpoints include AF burden, freedom from AF/AT after repeat procedures and quality of life.

CONCLUSIONS

The VENUS-AF and MARS-AF will determine the safety and potential rhythm control benefit of VOM ethanol infusion when added to PVI in patients with persistent AF undergoing de novo or repeat ablation, respectively.

The Role of Echocardiography in Determining the Method of Ablation for the Treatment of Paroxysmal Atrial Fibrillation: A Literature Review

Atrial fibrillation is the most common cardiac arrhythmia, affecting approximately 1 out of every 250 people. It is associated with thrombus formation in the left atrium, decreased cardiac output, and deterioration of the myocardium. There are multiple treatments available for paroxysmal atrial fibrillation. This literature review will assess the benefits, risks, and complications associated with radiofrequency ablation and cryoablation, which utilize heat and freezing mechanisms, respectively. The review will also assess the role of echocardiography in determining which treatment, if any, is appropriate for atrial fibrillation.

Contemporary approaches to persistent atrial fibrillation

Atrial fibrillation (AF) is currently the most commonly treated cardiac arrhythmia. It is generally a progressive disease, often more difficult to control as electromechanical remodeling alters the underlying substrate. Patients typically evolve from infrequent, self-terminating episodes, to more frequent and sustained events. In addition, atrial remodeling may make sinus rhythm more challenging to achieve. Although an ablation strategy limited to pulmonary vein isolation may be curative in those with paroxysmal AF, a more extensive approach is often required in those with persistent AF. This article discusses the current approaches and most recent advances in the ablation of persistent and long-standing persistent AF.

Current ablation strategies for persistent and long-standing persistent atrial fibrillation

Atrial fibrillation (AF) is associated with an increased risk of cardiac and overall mortality. Restoration and maintenance of sinus rhythm is of paramount importance if it can be accomplished without the use of antiarrhythmic drugs. Catheter ablation has evolved into a well-established treatment option for patients with symptomatic, drug-refractory AF. Ablation strategies which target the pulmonary veins are the cornerstone of AF ablation procedures, irrespective of the AF type. Ablation strategies in the setting of persistent and long-standing persistent AF are more complex. Many centers follow a stepwise ablation approach including pulmonary vein antral isolation as the initial step, electrogram-based ablation at sites exhibiting complex fractionated atrial electrograms, and linear lesions. Up to now, no single strategy is uniformly effective in patients with persistent and long-standing persistent AF. The present study reviewed the efficacy of the current ablation strategies for persistent and long-standing persistent AF.

Ablation strategies for atrial fibrillation

Atrial fibrillation remains the most common arrhythmia in the USA and is associated with an increased risk for stroke, congestive heart failure and overall mortality. There has been a tremendous advance in the field of catheter ablation of atrial fibrillation that has resulted in better outcomes for patients. The approach for ablation of atrial fibrillation can be different depending on patients' presentation of paroxysmal or persistent atrial fibrillation. Pulmonary vein isolation remains the cornerstone of any ablation strategy for atrial fibrillation; however, further ablation, end points of the procedure, clinical end points for successful ablation and appropriate follow-up remain controversial. We aim to discuss these different approaches and the major controversies in catheter ablation of atrial fibrillation.