EDITORIAL COMMENTARY
Can left atrial function guide atrial fibrillation ablation? Gregory E. Supple, MD, FACC From the Division of Cardiac Electrophysiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. It has been over 15 years since Haïssaguerre et al1 described successful ablation of paroxysmal atrial fibrillation (AF) by targeting pulmonary vein triggers. In the intervening years, AF ablation has exploded to become a dominant procedure in electrophysiology. Pulmonary vein isolation remains the cornerstone of AF ablation,2 yet despite countless studies and an expanding arsenal of tools and techniques, the outcomes of AF ablation have never improved dramatically beyond those initially achieved by Haïssaguerre. In the face of an ever-growing population of patients with symptomatic AF, better ablation strategies have proven elusive. In light of the potential complications of AF ablation, there is a clear need to improve procedure effectiveness. However, we also need better ways to predict the effectiveness of the procedure to guide patient selection. Multiple studies have demonstrated that increased left atrial (LA) size correlates with worse AF ablation outcomes3–5 and that the results of ablation of paroxysmal AF are better than those of ablation of persistent AF.6 In this issue of HeartRhythm, Montserrat et al7 evaluate markers of LA function using 2-dimensional echocardiographic speckle tracking to assess LA strain and strain rate as well as compare these markers in patients with or without recurrent AF after first or second ablation. Recently, there has been a growing literature on the evaluation of atrial strain that has demonstrated its predictive value (1) to identify the risk of AF after cardiac surgery,8,9 (2) as an additive measure to the CHA2DS2-VASc score to predict thromboembolic risk in AF,10,11 and (3) to help predict the success rates after ablation.12,13 Other work has demonstrated that LA strain and strain rate correlate with LA structural remodeling seen on magnetic resonance imaging14 and has also shown them to correlate with fibrosis seen on histopathology.15 While some studies have demonstrated that LA strain correlates with LA size,16 others have suggested that LA strain may be an independent, or even more sensitive, predictor of the risk of progressive or recurrent AF. This growing literature clearly demonstrates that LA function might have an important impact on AF with respect to its risk of development and persistence, susceptibility to Address reprint requests and correspondence: Dr Gregory E. Supple, University of Pennsylvania School of Medicine, 3400 Spruce St, 9 Founders, Philadelphia, PA 19104. E-mail address: gregory.supple@uphs. upenn.edu.
1547-5271/$-see front matter B 2015 Heart Rhythm Society. All rights reserved.
treatment, and the associated risk of stroke. One might postulate that a decline in LA strain may represent an earlier marker of LA dysfunction before the LA begins to dilate or before AF becomes more persistent. In their article, Montserrat et al found that markers of LA strain and strain rate were significantly lower in the AF ablation population than in a group of healthy controls. Furthermore, these markers were significantly lower in the population of patients with recurrent AF after both a first and a second ablation procedure. In multivariate analysis, lower LA systolic strain remained the only variable independently associated with recurrent AF after first and second ablation. They found no significant difference in LA size or in whether AF was paroxysmal or persistent between the groups with and without recurrent AF. On the basis of these findings, Montserrat et al concluded that LA strain may be a more sensitive measure than LA size to predict LA status and therefore the risk of recurrent AF. They suggested that surgical ablation might be considered in patients expected to be at a higher risk of recurrence based on lower LA strain values. However, one must interpret these results with caution, given the small sample size. It is surprising that characteristics that might represent more advanced LA dysfunction (LA size and persistent AF) were not associated with a higher recurrence of AF in this study. Additional studies and larger sample sizes are certainly needed to confirm these results and determine whether LA strain might be a useful predictive tool. The noninvasive nature and relative ease of the technique are attractive, and thus it may be more widely applicable than MRI delayed-enhancement imaging or LA voltage mapping. The additional results of their study highlighted the ongoing frustration with AF ablation. The 6-month success rates of ablation (56% after first ablation and 63% after second ablation) were typically disheartening. If LA strain proves to be a predictive tool, we might hope to improve these numbers or to at least provide a better estimate of the odds of success for our patients. Finally, in patients undergoing repeat ablation in this study, 100% demonstrated reconnected pulmonary veins. A recent study17 in HeartRhythm demonstrated a high incidence of PV reconnection after ablation, but the incidence was not significantly different in patients with and without recurrent AF. These findings beg the question: What http://dx.doi.org/10.1016/j.hrthm.2014.09.045
20 does ablation achieve? If atrial strain is a marker of successful ablation, it further highlights that in this disease of both triggers and substrate, ablation of pulmonary vein triggers only treats part of the problem. However, if even durable pulmonary vein isolation cannot be achieved with ablation, improving AF ablation will remain as elusive as ever.
Heart Rhythm, Vol 12, No 1, January 2015
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10.
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References 1. Haïssaguerre M, Jaïs P, Shah DC, Takahashi A, Hocini M, Quiniou G, Garrigue S, Le Mouroux A, Le Métayer P, Clémenty J. Spontaneous initiation of AF by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339: 659–666. 2. Calkins H, Heinz H, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of AF: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. Heart Rhythm 2012;9:632–696. 3. Lo LW, Lin YJ, Tsao HM, et al. The impact of LA size on long-term outcome of catheter ablation of chronic AF. J Cardiovasc Electrophysiol 2009;20: 1211–1216. 4. Shin SH, Park MY, Oh WJ, Hong SJ, Pak HN, Song WH, Lim DS, Kim YH, Shin WJ. LA volume is a predictor of AF recurrence after catheter ablation. J Am Soc Echocardiogr 2008;21:697–702. 5. Hof I, Chilukuri K, Arbab-Zadeh A, Scherr D, Dalal D, Nazarian S. Does LA volume and pulmonary venous anatomy predict the outcome of catheter ablation of AF? J Cardiovasc Electrophysiol 2009;20:1005–1010. 6. Bhargava M, Di Biase L, Mohanty P, et al. Impact of type of AF and repeat catheter ablation on long-term freedom from AF: results from multicenter study. Heart Rhythm 2009;6:1403–1412. 7. Montserrat S, Gabrielli L, Bijnens B, Borràs R, Berruezo A, Poyatos S, Brugada J, Mont L, Sitges M. LA deformation predicts success of first and second percutaneous AF ablation. Heart Rhythm 2014;12:11–18. 8. Candan O, Ozdemir N, Aung SM, Dogan C, Karabay CY, Gecmen C, Omaygenç O, Güler A. LA longitudinal strain parameters predict postoperative persistent AF
12.
13.
14.
15.
16.
17.
following mitral valve surgery: a speckle tracking echocardiography study. Echocardiography 2013;30:1061–1068. Cameli M, Lisi M, Reccia R, et al. Pre-operative LA strain predicts post-operative AF in patients undergoing aortic valve replacement for aortic stenosis. Int J Cardiovasc Imaging 2014;30:279–286. Obokata M, Negishi K, Kurosawa K, Tateno R, Tange S, Arai M, Amano M, Kurabayashi M. LA strain provides incremental value for embolism risk stratification over CHA2DS2-VASc score and indicates prognostic impact in patients with AF. J Am Soc Echocardiogr 2014;27:709–716. Islas F, Olmos C, Vieira C, De Agustín JA, Marcos-Alberca P, Saltijeral A, Almería C, Rodrigo JL, García Fernández MA, Macaya C, Pérez de Isla L. Thromboembolic risk in AF: association between left atrium mechanics and risk scores. a study based on 3D wall-motion tracking technology. Echocardiography 2014. [Epub ahead of print]. Spethmann S, Stüer K, Diaz I, Althoff T, Hewing B, Baumann G, Dreger H, Knebel F. LA mechanics predict the success of pulmonary vein isolation in patients with AF. Interv Card Electrophysiol 2014;40:53–62. Morris DA, Parwani A, Huemer M, Wutzler A, Bekfani T, Attanasio P, Friedrich K, Kühnle Y, Haverkamp W, Boldt LH. Clinical significance of the assessment of the systolic and diastolic myocardial function of the left atrium in patients with paroxysmal AF and low CHADS(2) index treated with catheter ablation therapy. Am J Cardiol 2013;111:1002–1011. Kuppahally SS, Akoum N, Burgon NS, et al. LA strain and strain rate in patients with paroxysmal and persistent AF: relationship to LA structural remodeling detected by delayed-enhancement MRI. Circ Cardiovasc Imaging 2010;3: 231–239. Her AY, Choi EY, Shim CY, Song BW, Lee S, Ha JW, Rim SJ, Hwang KC, Chang BC, Chung N. Prediction of LA fibrosis with speckle tracking echocardiography in mitral valve disease: a comparative study with histopathology. Korean Circ J 2012;42:311–318. Chadaide S, Domsik P, Kalapos A, Sághy L, Forster T, Nemes A. Threedimensional speckle tracking echocardiography-derived LA strain parameters are reduced in patients with AF. Echocardiography 2013;30:1078–1083. Jiang RH, Po SS, Tung R, Liu Q, Sheng X, Zhang ZW, Sun YX, Yu L, Zhang P, Fu GS, Jiang CY. Incidence of pulmonary vein conduction recovery in patients without clinical recurrence after ablation of paroxysmal AF: mechanistic implications. Heart Rhythm 2014;11(6):969–976.
Can left atrial function guide atrial fibrillation ablation? Gregory E. Supple, MD, FACC From the Division of Cardiac Electrophysiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania. It has been over 15 years since Haïssaguerre et al1 described successful ablation of paroxysmal atrial fibrillation (AF) by targeting pulmonary vein triggers. In the intervening years, AF ablation has exploded to become a dominant procedure in electrophysiology. Pulmonary vein isolation remains the cornerstone of AF ablation,2 yet despite countless studies and an expanding arsenal of tools and techniques, the outcomes of AF ablation have never improved dramatically beyond those initially achieved by Haïssaguerre. In the face of an ever-growing population of patients with symptomatic AF, better ablation strategies have proven elusive. In light of the potential complications of AF ablation, there is a clear need to improve procedure effectiveness. However, we also need better ways to predict the effectiveness of the procedure to guide patient selection. Multiple studies have demonstrated that increased left atrial (LA) size correlates with worse AF ablation outcomes3–5 and that the results of ablation of paroxysmal AF are better than those of ablation of persistent AF.6 In this issue of HeartRhythm, Montserrat et al7 evaluate markers of LA function using 2-dimensional echocardiographic speckle tracking to assess LA strain and strain rate as well as compare these markers in patients with or without recurrent AF after first or second ablation. Recently, there has been a growing literature on the evaluation of atrial strain that has demonstrated its predictive value (1) to identify the risk of AF after cardiac surgery,8,9 (2) as an additive measure to the CHA2DS2-VASc score to predict thromboembolic risk in AF,10,11 and (3) to help predict the success rates after ablation.12,13 Other work has demonstrated that LA strain and strain rate correlate with LA structural remodeling seen on magnetic resonance imaging14 and has also shown them to correlate with fibrosis seen on histopathology.15 While some studies have demonstrated that LA strain correlates with LA size,16 others have suggested that LA strain may be an independent, or even more sensitive, predictor of the risk of progressive or recurrent AF. This growing literature clearly demonstrates that LA function might have an important impact on AF with respect to its risk of development and persistence, susceptibility to Address reprint requests and correspondence: Dr Gregory E. Supple, University of Pennsylvania School of Medicine, 3400 Spruce St, 9 Founders, Philadelphia, PA 19104. E-mail address: gregory.supple@uphs. upenn.edu.
1547-5271/$-see front matter B 2015 Heart Rhythm Society. All rights reserved.
treatment, and the associated risk of stroke. One might postulate that a decline in LA strain may represent an earlier marker of LA dysfunction before the LA begins to dilate or before AF becomes more persistent. In their article, Montserrat et al found that markers of LA strain and strain rate were significantly lower in the AF ablation population than in a group of healthy controls. Furthermore, these markers were significantly lower in the population of patients with recurrent AF after both a first and a second ablation procedure. In multivariate analysis, lower LA systolic strain remained the only variable independently associated with recurrent AF after first and second ablation. They found no significant difference in LA size or in whether AF was paroxysmal or persistent between the groups with and without recurrent AF. On the basis of these findings, Montserrat et al concluded that LA strain may be a more sensitive measure than LA size to predict LA status and therefore the risk of recurrent AF. They suggested that surgical ablation might be considered in patients expected to be at a higher risk of recurrence based on lower LA strain values. However, one must interpret these results with caution, given the small sample size. It is surprising that characteristics that might represent more advanced LA dysfunction (LA size and persistent AF) were not associated with a higher recurrence of AF in this study. Additional studies and larger sample sizes are certainly needed to confirm these results and determine whether LA strain might be a useful predictive tool. The noninvasive nature and relative ease of the technique are attractive, and thus it may be more widely applicable than MRI delayed-enhancement imaging or LA voltage mapping. The additional results of their study highlighted the ongoing frustration with AF ablation. The 6-month success rates of ablation (56% after first ablation and 63% after second ablation) were typically disheartening. If LA strain proves to be a predictive tool, we might hope to improve these numbers or to at least provide a better estimate of the odds of success for our patients. Finally, in patients undergoing repeat ablation in this study, 100% demonstrated reconnected pulmonary veins. A recent study17 in HeartRhythm demonstrated a high incidence of PV reconnection after ablation, but the incidence was not significantly different in patients with and without recurrent AF. These findings beg the question: What http://dx.doi.org/10.1016/j.hrthm.2014.09.045
20 does ablation achieve? If atrial strain is a marker of successful ablation, it further highlights that in this disease of both triggers and substrate, ablation of pulmonary vein triggers only treats part of the problem. However, if even durable pulmonary vein isolation cannot be achieved with ablation, improving AF ablation will remain as elusive as ever.
Heart Rhythm, Vol 12, No 1, January 2015
9.
10.
11.
References 1. Haïssaguerre M, Jaïs P, Shah DC, Takahashi A, Hocini M, Quiniou G, Garrigue S, Le Mouroux A, Le Métayer P, Clémenty J. Spontaneous initiation of AF by ectopic beats originating in the pulmonary veins. N Engl J Med 1998;339: 659–666. 2. Calkins H, Heinz H, Cappato R, et al. 2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of AF: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. Heart Rhythm 2012;9:632–696. 3. Lo LW, Lin YJ, Tsao HM, et al. The impact of LA size on long-term outcome of catheter ablation of chronic AF. J Cardiovasc Electrophysiol 2009;20: 1211–1216. 4. Shin SH, Park MY, Oh WJ, Hong SJ, Pak HN, Song WH, Lim DS, Kim YH, Shin WJ. LA volume is a predictor of AF recurrence after catheter ablation. J Am Soc Echocardiogr 2008;21:697–702. 5. Hof I, Chilukuri K, Arbab-Zadeh A, Scherr D, Dalal D, Nazarian S. Does LA volume and pulmonary venous anatomy predict the outcome of catheter ablation of AF? J Cardiovasc Electrophysiol 2009;20:1005–1010. 6. Bhargava M, Di Biase L, Mohanty P, et al. Impact of type of AF and repeat catheter ablation on long-term freedom from AF: results from multicenter study. Heart Rhythm 2009;6:1403–1412. 7. Montserrat S, Gabrielli L, Bijnens B, Borràs R, Berruezo A, Poyatos S, Brugada J, Mont L, Sitges M. LA deformation predicts success of first and second percutaneous AF ablation. Heart Rhythm 2014;12:11–18. 8. Candan O, Ozdemir N, Aung SM, Dogan C, Karabay CY, Gecmen C, Omaygenç O, Güler A. LA longitudinal strain parameters predict postoperative persistent AF
12.
13.
14.
15.
16.
17.
following mitral valve surgery: a speckle tracking echocardiography study. Echocardiography 2013;30:1061–1068. Cameli M, Lisi M, Reccia R, et al. Pre-operative LA strain predicts post-operative AF in patients undergoing aortic valve replacement for aortic stenosis. Int J Cardiovasc Imaging 2014;30:279–286. Obokata M, Negishi K, Kurosawa K, Tateno R, Tange S, Arai M, Amano M, Kurabayashi M. LA strain provides incremental value for embolism risk stratification over CHA2DS2-VASc score and indicates prognostic impact in patients with AF. J Am Soc Echocardiogr 2014;27:709–716. Islas F, Olmos C, Vieira C, De Agustín JA, Marcos-Alberca P, Saltijeral A, Almería C, Rodrigo JL, García Fernández MA, Macaya C, Pérez de Isla L. Thromboembolic risk in AF: association between left atrium mechanics and risk scores. a study based on 3D wall-motion tracking technology. Echocardiography 2014. [Epub ahead of print]. Spethmann S, Stüer K, Diaz I, Althoff T, Hewing B, Baumann G, Dreger H, Knebel F. LA mechanics predict the success of pulmonary vein isolation in patients with AF. Interv Card Electrophysiol 2014;40:53–62. Morris DA, Parwani A, Huemer M, Wutzler A, Bekfani T, Attanasio P, Friedrich K, Kühnle Y, Haverkamp W, Boldt LH. Clinical significance of the assessment of the systolic and diastolic myocardial function of the left atrium in patients with paroxysmal AF and low CHADS(2) index treated with catheter ablation therapy. Am J Cardiol 2013;111:1002–1011. Kuppahally SS, Akoum N, Burgon NS, et al. LA strain and strain rate in patients with paroxysmal and persistent AF: relationship to LA structural remodeling detected by delayed-enhancement MRI. Circ Cardiovasc Imaging 2010;3: 231–239. Her AY, Choi EY, Shim CY, Song BW, Lee S, Ha JW, Rim SJ, Hwang KC, Chang BC, Chung N. Prediction of LA fibrosis with speckle tracking echocardiography in mitral valve disease: a comparative study with histopathology. Korean Circ J 2012;42:311–318. Chadaide S, Domsik P, Kalapos A, Sághy L, Forster T, Nemes A. Threedimensional speckle tracking echocardiography-derived LA strain parameters are reduced in patients with AF. Echocardiography 2013;30:1078–1083. Jiang RH, Po SS, Tung R, Liu Q, Sheng X, Zhang ZW, Sun YX, Yu L, Zhang P, Fu GS, Jiang CY. Incidence of pulmonary vein conduction recovery in patients without clinical recurrence after ablation of paroxysmal AF: mechanistic implications. Heart Rhythm 2014;11(6):969–976.
