Mapping and ablating stable sources for atrial fibrillation: summary of the literature on Focal Impulse and Rotor Modulation (FIRM)
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Atrial fibrillation (AF) is the most common sustained arrhythmia and the most common indication for catheter ablation. However, despite substantial technical advances in mapping and energy delivery, ablation outcomes remain suboptimal. A major limitation to AF ablation is that the areas targeted for ablation are rarely of proven mechanistic importance, in sharp contrast to other arrhythmias in which ablation targets demonstrated mechanisms in each patient. Focal impulse and rotor modulation (FIRM) is a new approach to demonstrate the mechanisms that sustain AF (“substrates”) in each patient that can be used to guide ablation then confirm elimination of each mechanism. FIRM mapping reveals that AF is sustained by 2–3 rotors and focal sources, with a greater number in patients with persistent than paroxysmal AF, lying within spatially reproducible 2.2 ± 1.4-cm2 areas in diverse locations. This temporospatial reproducibility, now confirmed by several groups using various methods, changes the concepts regarding AF-sustaining mechanisms, enabling localized rather than widespread ablation. Mechanistically, the role of rotors and focal sources in sustaining AF has been demonstrated by the acute and chronic success of source (FIRM) ablation alone. Clinically, adding FIRM to conventional ablation substantially improves arrhythmia freedom compared with conventional ablation alone, and ongoing randomized trials are comparing FIRM—ablation with and without conventional ablation to conventional ablation alone. In conclusion, ablation of patient-specific AF-sustaining mechanisms (substrates), as exemplified by FIRM, may be central to substantially improving AF ablation outcomes.
KeywordsAtrial fibrillation Rotors Ablation Focal sources Substrates Phase mapping
This work was supported by grants to S.M. Narayan from the NIH (HL83359 and HL103800).
Conflict of interest
Dr. Narayan is a coauthor of intellectual property owned by the University of California Regents and licensed to Topera Inc. Topera does not sponsor any research, including that presented here. Dr. Narayan holds equity in Topera and reports having received honoraria from Medtronic, St. Jude Medical, and Biotronik. The other authors report no conflicts.
- 1.Calkins H., Kuck K.H., Cappato R. et al. (2012). 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: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC) and the European Cardiac Arrhythmia Society (ECAS); and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). Endorsed by the governing bodies of the American College of Cardiology Foundation, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, the Asia Pacific Heart Rhythm Society, and the Heart Rhythm Society. J Interv Card Electrophysiol, 33, 171–257.Google Scholar
- 5.Cox, J. L., Canavan, T. E., Schuessler, R. B., et al. (1991). The surgical treatment of atrial fibrillation. II. Intraoperative electrophysiologic mapping and description of the electrophysiologic basis of atrial flutter and atrial fibrillation. The Journal of thoracic and cardiovascular surgery, 101, 406–426.PubMedGoogle Scholar
- 6.Jadidi, A.S., Cochet, H., Shah, A.J., et al. (2013). Inverse relationship between fractionated electrograms and atrial fibrosis in persistent atrial fibrillation: a combined MRI and high density mapping. J Am Coll Cardiol.Google Scholar
- 10.Shivkumar, K., Ellenbogen, K. A., Hummel, J. D., Miller, J. M., & Steinberg, J. S. (2012). Acute termination of human atrial fibrillation by identification and catheter ablation of localized rotors and sources: first multicenter experience of Focal Impulse and Rotor Modulation (FIRM) ablation. Journal of Cardiovascular Electrophysiology, 23, 1277–1285.PubMedCentralPubMedCrossRefGoogle Scholar
- 16.Narayan, S.M., Krummen, D.E., Donsky, A., Swarup, V., Miller, J.M. (2013). Precise Rotor Elimination without Concomitant pulmonary vein Isolation for the Successful Elimination of paroxysmal atrial fibrillation. PRECISE-PAF. Heart Rhythm, 10, 1414-LB01-05.Google Scholar
- 17.Narayan, S. M., Krummen, D. E., Clopton, P., Shivkumar, K., & Miller, J. M. (2013). Direct or coincidental elimination of stable rotors or focal sources may explain successful atrial fibrillation ablation: on-treatment analysis of the CONFIRM (CONventional ablation for AF with or without Focal Impulse and Rotor Modulation) Trial. Journal of the American College of Cardiology, 62, 138–147.PubMedCentralPubMedCrossRefGoogle Scholar
- 18.Narayan, S. M., Krummen, D. E., Shivkumar, K., Clopton, P., Rappel, W.-J., & Miller, J. M. (2012). Treatment of atrial fibrillation by the ablation of localized sources: CONFIRM (Conventional Ablation for Atrial Fibrillation With or Without Focal Impulse and Rotor Modulation) trial. Journal of the American College of Cardiology, 60, 628–636.PubMedCentralPubMedCrossRefGoogle Scholar
- 19.Miller, J.M., Daubert, J., Day J., et al. (2013). Long-term results of patients receiving Focal Impulse and Rotor Modulation (FIRM) for atrial fibrillation: extended multi-center experience (abstract). in review Google Scholar
- 24.Haddad, M.E., Houben, R., Tavernier, R., Duytschaever, M. (2014). A stable reentrant circuit with spiral wave activation driving atrial tachycardia. Heart Rhythm in press.Google Scholar
- 27.Baykaner, T., Clopton, P., Schricker, A.A., Lalani, G., Krummen, D.E., Narayan, S.M. (2013). Targeted ablation at stable atrial fibrillation sources improves success over conventional ablation in high risk patients: a substudy of the CONFIRM trial. Canadian J Cardiology, 29(10), 1218–26.Google Scholar
- 28.Narayan, S.M., Shivkumar, K., Mittal, S., et al. (2011). CONventional ablation for atrial fibrillation with or without Focal Impulse and Rotor Modulation: the CONFIRM trial (Late Breaking Clinical Trial Abstract). Heart Rhythm, 8, LB-04.Google Scholar
- 29.Narayan, S.M., Baykaner, T., Clopton, P., et al. (2014). Ablation of rotor and focal sources reduces late recurrence of atrial fibrillation compared to trigger ablation alone: extended follow up of the CONFIRM (CONventional ablation with or without Focal Impulse and Rotor Modulation) trial. Journal of the American College of Cardioliology in press.Google Scholar
- 30.Miller, J.M., Daubert, J., Day, J., et al. (2013). Long-term results of patients receiving Focal Impulse and Rotor Modulation (FIRM) for atrial fibrillation: extended multi-center experience (abstract). Circulation, 128.Google Scholar
- 31.Kowal, R. C., Daubert, J., Day, J., et al. (2013). Results of Focal Impulse and Rotor Modulation (FIRM) for atrial fibrillation Are equivalent between patients treated in San Diego compared with sites new to FIRM ablation: an extended multi-center experience (abstract). Heart Rhythm, 10, S479.Google Scholar
- 33.Swarup, V., Kowal, R. C., Daubert, J., et al. (2013). Rotors on Focal Impulse and Rotor Mapping are stable over thousands of cycles. Heart Rhythm, 10, S479.Google Scholar
- 34.Narayan, S. M., Shivkumar, K., Krummen, D. E., Miller, J. M., & Rappel, W.-J. (2013). Panoramic electrophysiological mapping but not individual electrogram morphology identifies sustaining sites for human atrial fibrillation: stable atrial fibrillation rotors and focal sources relate poorly to fractionated electrograms (AF rotors and focal sources relate poorly to fractionated electrograms). Circulation Arrhythmia and Electrophysiology, 6, 58–67.PubMedCentralPubMedCrossRefGoogle Scholar