Ablation of atrial fibrillation

https://doi.org/10.1016/j.tcm.2014.11.009Get rights and content

Abstract

Ablation is increasingly used to treat AF, since recent trials of pharmacological therapy for AF have been disappointing. Ablation has been shown to improve maintenance of sinus rhythm compared to pharmacological therapy in many multicenter trials, although success rates remain suboptimal. This review will discuss several trends in the field of catheter ablation, including studies to advance our understanding of AF mechanisms in different patient populations, innovations in detecting and classifying AF, use of this information to improve strategies for ablation, technical innovations that have improved the ease and safety of ablation, and novel approaches to surgical therapy and imaging. These trends are likely to further improve results from AF ablation in coming years as it becomes an increasingly important therapeutic option for many patients.

Introduction

Ablation therapy is widely used to treat atrial fibrillation (AF), a disease that affects approximately 30 million individuals worldwide [1] and is a major cause of stroke, heart failure, and death. The use of ablation has been encouraged by the disappointing results of important trials that question both pillars of pharmacological therapy—to strictly control ventricular rate [2] and to maintain sinus rhythm [3], [4]. Buoyed by the success of ablation for “simple” supraventricular and ventricular arrhythmias, ablation is increasingly used for AF [5] and is superior to pharmacological therapy for patients with early (paroxysmal) [6], [7] to advanced (persistent) AF [8]. Nevertheless, fibrillation is a complex disease and the overall success of ablation remains lower [9] for AF than for other arrhythmias [6], [7], [10], [11], [12], [13]—despite remarkable successes in individual patients. This has fueled a vibrant culture of intense patient-focused translational research that has characterized the field since its earliest days [14], [15], [16]. This review addresses trends in the field of catheter ablation, focused on defining AF mechanisms and translating them to improved strategies to ultimately improve outcomes in individual patients.

Section snippets

Explaining the diverse trends in AF ablation success rates

The success of AF ablation is widely quoted as 60–80% at 1 year for multiple procedures (average of 1–2) and 40–60% at 1 year for a single procedure [12], [17]. However, these figures mask a remarkable heterogeneity between patients (Fig. 1). The most common approach to AF ablation is pulmonary vein isolation (PVI) to prevent triggers from the pulmonary veins from initiating AF (Fig. 2). However, data consistently show that this uniform procedural goal, applied with the same diligence by

Trends in who to ablate?

Societal guidelines reserve ablation for patients with symptomatic AF [12], and several studies show that ablation in such patients improves quality of life compared to pharmacologic therapy [38], [39], [40]. Nevertheless, this reveals an inconvenient paradox, since success is then measured by eliminating asymptomatic and symptomatic AF. If the results of major ongoing studies ,including CABANA (Clinicaltrials.gov: NCT00911508), CASTLE-AF (Clinicaltrials.gov: NCT00643188), and EAST

Trends in mechanistic understanding to improve ablation of AF

It is generally acknowledged that a better mechanistic understanding of human AF will enable better ablation tailoring to patient-specific mechanisms, i.e., a therapeutically focused functional disease classification. There has been intense investigation into this area in recent years, with several promising advances.

Tachyarrhythmias initiate from a “trigger,” such as a premature beat, and are then maintained by sustaining mechanisms (“substrates”). In AF, the terms trigger and substrate are

Evolving technical aspects of ablation: Less is more

A recent trend is to attempt to limit the amount of tissue destruction during ablation, exemplified by the promise of individualized strategies based on mapping AF [68], [84] that may reduce ablation yet improve long-term outcomes [34].

Nevertheless, there are still patients in whom catheter ablation may not result in long-term freedom from AF. While our understanding of the mechanisms involved in patients with grossly dilated atria and long-standing persistent AF improves, surgical AF ablation

Management of anticoagulation

Minimizing the risk of stroke is a central pillar of AF management, regardless of whether patients are being ablated. Recent landmark trials with the non-vitamin K oral anticoagulants (NOACs) have shifted emphasis away from warfarin [101], although actual prescribing habits vary geographically [102]. Specific challenges of AF ablation in patients using NOACs were the relative lack of data during cardioversion, although recent studies confirm safety [103], and ablation, since it is difficult to

Complications of AF ablation

The specific risks of AF ablation reflect potentially extensive ablation as well as the proximity of atria to adnexae such as the esophagus, phrenic nerves, and other vasculature [105], [106]. Awareness of these risks has improved procedural technique, e.g., eliminating PV stenosis by ablating widely outside PVs (Fig. 2B) instead of close to the thin-walled PVs, while better sheath management and anticoagulation can reduce thromboembolic risk. Accordingly, AF ablation procedural safety has

Conclusions

Ablation for AF is increasingly used because it has been shown to improve maintenance of sinus rhythm compared to drug therapy in numerous multicenter trials. Although success rates remain suboptimal, the remarkable success of ablation in many patients provides a foundation for future advancements. A mechanistic classification of AF will enable better guidance on how to direct ablation in specific populations and should also lead to improved ablation outcomes. Technical advances have improved

References (111)

  • C. Schmitt et al.

    Biatrial multisite mapping of atrial premature complexes triggering onset of atrial fibrillation

    Am J Cardiol

    (2002)
  • D.G. Katritsis et al.

    Autonomic denervation added to pulmonary vein isolation for paroxysmal atrial fibrillation: a randomized clinical trial

    J Am Coll Cardiol

    (2013)
  • H. Oral et al.

    Randomized comparison of encircling and nonencircling left atrial ablation for chronic atrial fibrillation

    Heart Rhythm

    (2005)
  • R.H. Jiang et al.

    Incidence of pulmonary vein conduction recovery in patients without clinical recurrence after ablation of paroxysmal atrial fibrillation: mechanistic implications

    Heart Rhythm

    (2014)
  • S.M. Narayan et al.

    Direct or concidental ablation of localized sources may explain the success of atrial fibrillation ablation. On treatment analysis from the CONFIRM Trial

    J Am Coll Cardiol

    (2013)
  • H. Oral et al.

    A randomized assessment of the incremental role of ablation of complex fractionated atrial electrograms after antral pulmonary vein isolation for long-lasting persistent atrial fibrillation

    J Am Coll Cardiol

    (2009)
  • G.K. Moe et al.

    A computer model of atrial fibrillation

    Am Heart J

    (1964)
  • S.M. Narayan et al.

    Treatment of atrial fibrillation by the ablation of localized sources: the conventional ablation for atrial fibrillation with or without focal impulse and rotor modulation: CONFIRM Trial

    J Am Coll Cardiol

    (2012)
  • G. Lalani et al.

    Atrial conduction slows immediately before the onset of human atrial fibrillation: a bi-atrial contact mapping study of transitions to atrial fibrillation

    J Am Coll Cardiol

    (2012)
  • B. Ghoraani et al.

    Localized rotational activation in the left atrium during human atrial fibrillation: relationship to complex fractionated atrial electrograms and low-voltage zones

    Heart Rhythm

    (2013)
  • D.L. Packer et al.

    Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) Pivotal Trial

    J Am Coll Cardiol

    (2013)
  • R. Casado-Arroyo et al.

    Phrenic nerve paralysis during cryoballoon ablation for atrial fibrillation: a comparison between the first- and second-generation balloon

    Heart Rhythm

    (2013)
  • B. Gersak et al.

    European experience of the convergent atrial fibrillation procedure: multicenter outcomes in consecutive patients

    J Thorac Cardiovasc Surg

    (2014)
  • M. Wright et al.

    Real-time lesion assessment using a novel combined ultrasound and radiofrequency ablation catheter

    Heart Rhythm

    (2011)
  • A. Natale et al.

    Paroxysmal AF Catheter ablation with a contact force sensing catheter: results of the prospective, multicenter SMART-AF Trial

    J Am Coll Cardiol

    (2014)
  • S.S. Chugh et al.

    Worldwide epidemiology of atrial fibrillation: a global burden of disease 2010 study

    Circulation

    (2014)
  • I.C. Van Gelder et al.

    Lenient versus strict rate control in patients with atrial fibrillation

    N Engl J Med

    (2010)
  • D. Roy et al.

    Rhythm control versus rate control for atrial fibrillation and heart failure

    N Engl J Med

    (2008)
  • A. Deshmukh et al.

    In-hospital complications associated with catheter ablation of atrial fibrillation in the United States between 2000 and 2010: analysis of 93 801 procedures

    Circulation

    (2013)
  • D.J. Wilber et al.

    Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial

    J Am Med Assoc

    (2010)
  • H. Oral et al.

    Circumferential pulmonary-vein ablation for chronic atrial fibrillation

    N Engl J Med

    (2006)
  • H. Van Brabandt et al.

    Caution over use of catheter ablation for atrial fibrillation

    Br Med J

    (2013)
  • C.A. Morillo et al.

    Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of paroxysmal atrial fibrillation (RAAFT-2): a randomized trial

    JAMA

    (2014)
  • J.C. Nielsen et al.

    Radiofrequency ablation as initial therapy in paroxysmal atrial fibrillation

    New Engl J Med

    (2012)
  • C.H. Calkins

    2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

    Heart Rhythm

    (2012)
  • R. Parkash et al.

    Approach to the catheter ablation technique of paroxysmal and persistent atrial fibrillation: a meta-analysis of the randomized controlled trials

    J Cardiovasc Electrophysiol

    (2011)
  • J.F. Swartz et al.

    A catheter-based curative approach to atrial fibrillation in humans

    Circulation

    (1994)
  • P. Jais et al.

    A focal source of atrial fibrillation treated by discrete radiofrequency ablation

    Circulation

    (1997)
  • M. Haissaguerre et al.

    Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins

    N Engl J Med

    (1998)
  • A.N. Ganesan et al.

    Long-term outcomes of catheter ablation of atrial fibrillation: a systematic review and meta-analysis

    J Am Heart Assoc

    (2013)
  • J.W. McCready et al.

    Predictors of recurrence following radiofrequency ablation for persistent atrial fibrillation

    Europace

    (2011)
  • A. Verma et al.

    Optimal method and outcomes of catheter ablation of persistent AF: the STARAF 2 Trial

    Eur Heart J

    (2014)
  • V. Fuster et al.

    ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society

    Circulation

    (2006)
  • G. Hindricks et al.

    Perception of atrial fibrillation before and after radiofrequency catheter ablation: relevance of asymptomatic arrhythmia recurrence

    Circulation

    (2005)
  • E.I. Charitos et al.

    A comprehensive evaluation of rhythm monitoring strategies for the detection of atrial fibrillation recurrence: insights from 647 continuously monitored patients and implications for monitoring after therapeutic interventions

    Circulation

    (2012)
  • A. Jahangir et al.

    Long-term progression and outcomes with aging in patients with lone atrial fibrillation: a 30-year follow-up study

    Circulation

    (2007)
  • C.T. January et al.

    2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society

    J Am Coll Cardiol

    (2014)
  • C.A. Morillo et al.

    Radiofrequency ablation vs antiarrhythmic drugs as first-line treatment of paroxysmal atrial fibrillation (RAAFT-2): a randomized trial

    J Am Med Assoc

    (2014)
  • J.S. Healey et al.

    Subclinical atrial fibrillation and the risk of stroke

    N Engl J Med

    (2012)
  • T. Sanna et al.

    Cryptogenic stroke and underlying atrial fibrillation

    N Engl J Med

    (2014)
  • Cited by (0)

    Disclosures: M.W. reports that he has received consulting fees from Philips Healthcare and Biosense-Webster, and participates in educational programs for Biosense-Webster and St. Jude Medical. S.M.N. reports research funding from National Institutes of Health, USA (HL83359, HL122384, and HL103800). S.M.N. is a co-inventor of intellectual property owned by University of California, and licensed to Topera in which he holds equity. He has received consulting fees from the American College of Cardiology, Janssen Pharmaceuticals, and Medtronic.

    View full text