Медицинская литература. Новинки

 

 

 

 

 

 

Значение двухмерной спекл-трекинг эхокардиографии левого предсердия у пациентов с фибрилляций предсердий

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Данная статья представляет собой обзор литературы, посвященный анализу перспективных направлений использования показателей деформации левого предсердия, оцененных с помощью спеклтрекинг-эхокардиографии для прогнозирования фибрилляции предсердий (ФП). Показатели деформации левого предсердия в различные фазы сердечного цикла являются независимыми предикторами ФП как у пациентов с сердечной недостаточностью, так и в общей популяции. Добавление показателей деформации левого предсердия к традиционным эхокардиографическим параметрам позволит эффективно выбирать пациентов с ФП как для катетерной абляции, так и определять пациентов с высоким риском рецидива ФП после катетерной абляции.

Ключевые слова:
спекл-трекинг эхокардиография, деформация левого предсердия, фибрилляция предсердий, катетерная абляция, speckle-tracking echocardiography, left atrial strain, atrial fibrillation, catheter ablation

Литература:
1.Hindricks G., Potpara T., Dagres N., Arbelo E., Bax J.J., Blomstrom-Lundqvist C., Boriani G., Castella M., Dan G.A., Dilaveris P.E., Fauchier L., Filippatos G., Kalman J.M., La Meir M., Lane D.A., Lebeau J.P., Lettino M., Lip G.Y.H., Pinto F.J., Thomas G.N. ESC Scientific Document Group. 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for CardioThoracic Surgery (EACTS): The Task Force for the diagnosis and management of atrial fibrillation of the European Society of Cardiology (ESC) Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC. Eur. Heart J. 2021; 42 (5): 373–498. http://doi.org/10.1093/eurheartj/ehaa612
2.Chugh S.S., Havmoeller R., Narayanan K., Singh D., Rienstra M., Benjamin E.J., Gillum R.F., Kim Y.H., McAnulty J.H., Zheng Z.J., Forouzanfar M.H., Naghavi M., Mensah G.A., Ezzati M., Murray C.J. Worldwide epidemiology of atrial fibrillation: a Global Burden of Disease 2010 Study. Circulation. 2014; 129 (8): 837–847. http://doi.org/10.1161/CIRCULATIONAHA.113.005119
3.Arnautu S.F., Morariu V.I., Arnautu D.A., Tomescu M.C., Dan T.F., Dragos Jianu C. Left Atrial Strain Helps Identifying the Cardioembolic Risk in Transient Ischemic Attacks Patients with Silent Paroxysmal Atrial Fibrillation. Ther. Clin. Risk Manag. 2022; 18: 213–222. http://doi.org/10.2147/TCRM.S359490
4.Rasmussen S.M.A., Olsen F.J., Jorgensen P.G., Fritz-Hansen T., Jespersen T., Gislason G., BieringSorensen T. Utility of left atrial strain for predicting atrial fibrillation following ischemic stroke. Int. J. Cardiovasc. Imaging. 2019; 35 (9): 1605–1613. http://doi.org/10.1007/s10554-019-01601-0
5.Hauser R., Nielsen A.B., Skaarup K.G., Lassen M.C.H., Duus L.S., Johansen N.D., Sengelov M., Marott J.L., Jensen G., Schnohr P., Sogaard P., Mogelvang R., Biering-Sorensen T. Left atrial strain predicts incident atrial fibrillation in the general population: the Copenhagen City Heart Study. Eur. Heart J. Cardiovasc. Imaging. 2021; 23 (1): 52–60. http://doi.org/10.1093/ehjci/jeab202
6.Olsen F.J., Johansen N.D., Skaarup K.G., Lassen M.C.H., Ravnkilde K., Schnohr P., Jensen G.B., Marott J.L., Sogaard P., Mogelvang R., Biering-Sorensen T. Changes in left atrial structure and function over a decade in the general population. Eur. Heart J. Cardiovasc. Imaging. 2021; 23 (1): 124–136. https://doi.org/10.1093/ehjci/jeab173
7.Lang R.M., Badano L.P., Mor-Avi V., Afilalo J., Armstrong A., Ernande L., Flachskampf F.A., Foster E., Goldstein S.A., Kuznetsova T., Lancellotti P., Muraru D., Picard M.H., Rietzschel E.R., Rudski L., Spencer K.T., Tsang W., Voigt J.U. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J. Am. Soc. Echocardiogr. 2015; 28 (1): 1–39.e14. http://doi.org/10.1016/j.echo.2014.10.003
8.Kojima T., Kawasaki M., Tanaka R., Ono K., Hirose T., Iwama M., Watanabe T., Noda T., Watanabe S., Takemura G., Minatoguchi S. Left atrial global and regional function in patients with paroxysmal atrial fibrillation has already been impaired before enlargement of left atrium: velo city vector imaging echocardiography study. Eur. Heart J. Cardiovasc. Imaging. 2012; 13 (3): 227–234. http://doi.org/10.1093/ejechocard/jer281
9.Cameli M., Mandoli G.E., Loiacono F., Sparla S., Iardino E., Mondillo S. Left atrial strain: A useful index in atrial fibrillation. Int. J. Cardiol. 2016; 220: 208–213. http://doi.org/10.1016/j.ijcard.2016.06.197
10.Alekhin M.N. Two-dimensional speckle tracking of echocardiography for evaluation of myocardium and heart chambers. M.: Central State Medical Academy of the Presidential Administration of the Russian Federation, 2021: 48–56. (In Russian)
11.Motoc A., Luchian M.L., Scheirlynck E., Roosens B., Chameleva H., Gevers M., Galloo X., von Kemp B., Ramak R., Sieira J., de Asmundis C., Chierchia G.B., Magne J., Weytjens C., Droogmans S., Cosyns B. Incremental value of left atrial strain to predict atrial fibrillation recurrence after cryoballoon ablation. PloS One. 2021; 16 (11): e0259999. http://doi.org/10.1371/journal.pone.0259999
12.Voigt J.U., Malaescu G.G., Haugaa K., Badano L. How to do LA strain. Eur. Heart J. Cardiovasc. Imaging. 2020; 21 (7): 715–717. http://doi.org/10.1093/ehjci/jeaa091
13.Badano L.P., Kolias T.J., Muraru D., Abraham T.P., Aurigemma G., Edvardsen T., D'Hooge J., Donal E., Fraser A.G., Marwick T., Mertens L., Popescu B.A., Sengupta P.P., Lancellotti P., Thomas J.D., Voigt J.U., Industry representatives, & Reviewers: This document was reviewed by members of the 2016–2018 EACVI Scientific Documents Committee (2018). Standardization of left atrial, right ventricular, and right atrial deformation imaging using two-dimensional speckle tracking echocardiography: a consensus document of the EACVI/ ASE/Industry Task Force to standardize deformation imaging. Eur. Heart J. Cardiovasc. Imaging. 2018; 19 (6): 591–600. http://doi.org/10.1093/ehjci/jey042
14.Molnar A.A., Merkely B. The Added Value of Atrial Strain Assessment in Clinical Practice. Diagnostics (Basel). 2022; 12 (4): 982. http://doi.org/10.3390/diagnostics12040982
15.Kuppahally S.S., Akoum N., Burgon N.S., Badger T.J., Kholmovski E.G., Vijayakumar S., Rao S.N., Blauer J., Fish E.N., Dibella E.V., Macleod R.S., McGann C., Litwin S.E., Marrouche N.F. Left atrial strain and strain rate in patients with paroxysmal and persistent atrial fibrillation: relationship to left atrial structural remodeling detected by delayed-enhancement MRI. Circ. Cardiovasc. Imaging. 2010; 3 (3): 231–239. http://doi.org/10.1161/CIRCIMAGING.109.865683
16.Cameli M., Lisi M., Righini F.M., Massoni A., Natali B.M., Focardi M., Tacchini D., Geyer A., Curci V., Di Tommaso C., Lisi G., Maccherini M., Chiavarelli M., Massetti M., Tanganelli P., Mondillo S. Usefulness of atrial deformation analysis to predict left atrial fibrosis and endocardial thickness in patients undergoing mitral valve operations for severe mitral regurgitation secondary to mitral valve prolapse. Am. J. Cardiol. 2013; 111 (4): 595–601. http://doi.org/10.1016/j.amjcard.2012.10.049
17.Lisi M., Mandoli G.E., Cameli M., Pastore M.C., Righini F.M., Benfari G., Rubboli A., D'Ascenzi F., Focardi M., Tsioulpas C., Bernazzali S., Maccherini M., Lisi E., Lindqvist P., Valente S., Mondillo S., Henein M.Y. Left atrial strain by speckle tracking predicts atrial fibrosis in patients undergoing heart transplantation. Eur. Heart J. Cardiovasc. Imaging. 2022; 23(6): 829–835. http://doi.org/10.1093/ehjci/jeab106
18.Marchandise S., Garnir Q., Scavee C., Varnavas V., le Polain de Waroux J.B., Wauters A., Beauloye C., Roelants V., Gerber B.L. Prediction of Left Atrial Fibrosis and Success of Catheter Ablation by Speckle Tracking Echocardiography in Patients Imaged in Persistent Atrial Fibrillation. Front. Cardiovasc. Med. 2022; 9: 856796. http://doi.org/10.3389/fcvm.2022.856796
19.Huber M.P., Pandit J.A., Jensen P.N., Wiggins K.L., Patel R.B., Freed B.H., Bertoni A.G., Shah S.J., Heckbert S.R., Floyd J.S. Left Atrial Strain and the Risk of Atrial Arrhythmias From Extended Ambulatory Cardiac Monitoring: MESA. J. Am. Heart Assoc. 2022; 11 (21): e026875. http://doi.org/10.1161/JAHA.122.026875
20.Park J.J., Park J.H., Hwang I.C., Park J.B., Cho G.Y., Marwick T.H. Left Atrial Strain as a Predictor of New-Onset Atrial Fibrillation in Patients With Heart Failure. JACC Cardiovasc. Imaging. 2020; 13 (10): 2071–2081. http://doi.org/10.1016/j.jcmg.2020.04.031
21.Jasic-Szpak E., Marwick T. H., Donal E., Przewlocka-Kosmala M., Huynh Q., Gozdzik A., Woznicka A.K., Jankowska E.A., Ponikowski P., Kosmala W. Prediction of AF in Heart Failure With Preserved Ejection Fraction: Incremental Value of Left Atrial Strain. JACC. Cardiovasc. Imaging. 2021; 14 (1): 131–144. http://doi.org/10.1016/j.jcmg.2020.07.040
22.Furukawa A., Ishii K., Hyodo E., Shibamoto M., Komasa A., Nagai T., Tada E., Seino Y., Yoshikawa J. Three-Dimensional Speckle Tracking Imaging for Assessing Left Atrial Function in Hypertensive Patients With Paroxysmal Atrial Fibrillation. Int. Heart J. 2016; 57 (6): 705–711. http://doi.org/10.1536/ihj.16-121
23.Nakanishi K., Daimon M., Fujiu K., Iwama K., Yoshida Y., Hirose K., Mukai Y., Yamamoto Y., Nakao T., Oshima T., Matsubara T., Shimizu Y., Oguri G., Kojima T., Hasumi E., Morita H., Komuro I. Prevalence of glucose metabolism disorders and its association with left atrial remodelling before and after catheter ablation in patients with atrial fibrillation. Europace. 2023; 25 (5): euad119. Advance online publication. http://doi.org/10.1093/europace/euad119
24.Steger C., Pratter A., Martinek-Bregel M., Avanzini M., Valentin A., Slany J., Stollberger C. Stroke patients with atrial fibrillation have a worse prognosis than patients without: data from the Austrian Stroke registry. Eur. Heart J. 2004; 25 (19): 1734– 1740. http://doi.org/10.1016/j.ehj.2004.06.030
25.Sanna T., Diener H.C., Passman R.S., Di Lazzaro V., Bernstein R.A., Morillo C.A., Rymer M.M., Thijs V., Rogers T., Beckers F., Lindborg K., Brachmann J., CRYSTAL AF Investigators. Cryptogenic stroke and underlying atrial fibrillation. New Engl. J. Med. 2014; 370 (26): 2478–2486. http://doi.org/10.1056/NEJMoa1313600
26.Gladstone D.J., Spring M., Dorian P., Panzov V., Thorpe K.E., Hall J., Vaid H., O'Donnell M., Laupacis A., Cote R., Sharma M., Blakely J.A., Shuaib A., Hachinski V., Coutts S.B., Sahlas D.J., Teal P., Yip S., Spence J.D., Buck B., EMBRACE Investigators and Coordinators. Atrial fibrillation in patients with cryptogenic stroke. New Engl. J. Med. 2014; 370 (26): 2467–2477. http://doi.org/10.1056/NEJMoa1311376
27.Ble M., Benito B., Cuadrado-Godia E., PerezFernandez S., Gomez M., Mas-Stachurska A., Tizon-Marcos H., Molina L., Marti-Almor J., Cladellas M. Left Atrium Assessment by Speckle Tracking Echocardiography in Cryptogenic Stroke: Seeking Silent Atrial Fibrillation. J. Clin. Med. 2021; 10 (16): 3501. http://doi.org/10.3390/jcm10163501
28.Kamel H., Bartz T.M., Longstreth W.T., Jr Elkind M.S.V., Gottdiener J., Kizer J.R., Gardin J.M., Kim J., Shah S. Cardiac mechanics and incident ischemic stroke: the Cardiovascular Health Study. Sci. Rep. 2021; 11 (1): 17358. http://doi.org/10.1038/s41598-021-96702-z
29.Pagola J., Juega J., Francisco-Pascual J., Bustamante A., Penalba A., Pala E., Rodriguez M., De Lera-Alfonso M., Arenillas J.F., Cabezas J.A., Moniche F., de Torres R., Montaner J., GonzalezAlujas T., Alvarez-Sabin J., Molina C.A., CryptoAF study group. Predicting Atrial Fibrillation with High Risk of Embolization with Atrial Strain and NT-proBNP. Translat. Stroke Res. 2021; 12 (5): 735–741. http://doi.org/10.1007/s12975-020-00873-2
30.Sonaglioni A., Vincenti A., Baravelli M., Rigamonti E., Tagliabue E., Bassi P., Nicolosi G.L., Anza C., Lombardo M. Prognostic value of global left atrial peak strain in patients with acute ischemic stroke and no evidence of atrial fibrillation. Int. J. Cardiovasc. Imaging. 2019; 35 (4): 603–613. http://doi.org/10.1007/s10554-018-1485-z
31.Kim D., Shim C.Y., Cho I J., Kim Y.D., Nam H.S., Chang H.J., Hong G.R., Ha J.W., Heo J.H. Chung, N. Incremental Value of Left Atrial Global Longitudinal Strain for Prediction of Post Stroke Atrial Fibrillation in Patients with Acute Ischemic Stroke. J. Cardiovasc. Ultrasound. 2016; 24 (1): 20–27. http://doi.org/10.4250/jcu.2016.24.1.20
32.Fauchier L., Clementy N., Pelade C., Collignon C., Nicolle E., Lip G.Y. Patients With Ischemic Stroke and Incident Atrial Fibrillation: A Nationwide Cohort Study. Stroke. 2015; 46 (9): 2432–2437. http://doi.org/10.1161/STROKEAHA.115.010270
33.Obokata M., Negishi K., Kurosawa K., Tateno R., Tange S., Arai M., Amano M., Kurabayashi M. Left atrial strain provides incremental value for embolism risk stratification over CHA2DS2-VASc score and indicates prognostic impact in patients with atrial fibrillation. J. Am. Soc. Echocardiogr. 2014; 27 (7): 709–716.e4. http://doi.org/10.1016/j.echo.2014.03.010
34.Saha S.K., Anderson P.L., Caracciolo G., Kiotsekoglou A., Wilansky S., Govind S., Mori N., Sengupta P.P. Global left atrial strain correlates with CHADS2 risk score in patients with atrial fibrillation. J. Am. Soc. Echocardiogr. 2011; 24 (5): 506–512. http://doi.org/10.1016/j.echo.2011.02.012
35.Islas F., Olmos C., Vieira C., De Agustin J.A., Marcos-Alberca P., Saltijeral A., Almeria C., Rodrigo J.L., Garcia Fernandez M.A., Macaya C., Perez de Isla L. Thromboembolic risk in atrial fibrillation: association between left atrium mechanics and risk scores. A study based on 3D wall-motion tracking technology. Echocardiography. 2015; 32 (4): 644–653. http://doi.org/10.1111/echo.12711
36.Azemi T., Rabdiya V.M., Ayirala S.R., McCullough L.D., Silverman D.I. Left atrial strain is reduced in patients with atrial fibrillation, stroke or TIA, and low risk CHADS(2) scores. J. Am. Soc. Echocardiogr. 2012; 25 (12): 1327–1332. http://doi.org/10.1016/j.echo.2012.09.004
37.Kirchhof P., Benussi S., Kotecha D., Ahlsson A., Atar D., Casadei B., Castella M., Diener H.C., Heidbuchel H., Hendriks J., Hindricks G., Manolis A.S., Oldgren J., Popescu B.A., Schotten U., Van Putte B., Vardas P. ESC Scientific Document Group. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Eur. Heart J. 2016; 37 (38): 2893–2962. http://doi.org/10.1093/eurheartj/ehw210
38.Yamaguchi T., Marrouche N.F. Recurrence PostAtrial Fibrillation Ablation: Think Outside the Pulmonary Veins. Circ. Arrhythm. Electrophysiol. 2018; 11 (4): e006379. http://doi.org/10.1161/CIRCEP.118.006379
39.Mujovic N., Marinkovic M., Mihajlovic M., Mujovic N., Potpara T.S. Risk factor modification for the primary and secondary prevention of atrial fibrillation. Part 2. Kardiol. Pol. 2020; 78 (3): 192–202. http://doi.org/10.33963/KP.15240
40.Saraiva R.M., Demirkol S., Buakhamsri A., Greenberg N., Popovic Z.B., Thomas J.D., Klein A.L. Left atrial strain measured by twodimensional speckle tracking represents a new tool to evaluate left atrial function. J. Am. Soc. Echocardiogr. 2010; 23 (2): 172–180. http://doi.org/10.1016/j.echo.2009.11.003
41.Mirza M., Caracciolo G., Khan U., Mori N., Saha S.K., Srivathsan K., Altemose G., Scott L., Sengupta P., Jahangir A. Left atrial reservoir function predicts atrial fibrillation recurrence after catheter ablation: a two-dimensional speckle strain study. J. Interv. Card. Electrophysiol. 2011; 31 (3): 197–206. http://doi.org/10.1007/s10840-011-9560-6
42.Lee D.K., Shim J., Choi J.I., Kim Y.H., Oh Y.W., Hwang S.H. Left Atrial Fibrosis Assessed with Cardiac MRI in Patients with Paroxysmal and Those with Persistent Atrial Fibrillation. Radiology. 2019; 292 (3): 575–582. http://doi.org/10.1148/radiol.2019182629
43.Yasuda R., Murata M., Roberts R., Tokuda H., Minakata Y., Suzuki K., Tsuruta H., Kimura T., Nishiyama N., Fukumoto K., Aizawa Y., Tanimoto K., Takatsuki S., Abe T., Fukuda K. Left atrial strain is a powerful predictor of atrial fibrillation recurrence after catheter ablation: study of a heterogeneous population with sinus rhythm or atrial fibrillation. Eur. Heart J. Cardiovasc. Imaging. 2015; 16 (9): 1008–1014. http://doi.org/10.1093/ehjci/jev028
44.Morris D.A., Parwani A., Huemer M., Wutzler A., Bekfani T., Attanasio P., Friedrich K., Kuhnle Y., Haverkamp W., Boldt L.H. Clinical significance of the assessment of the systolic and diastolic myocardial function of the left atrium in patients with paroxysmal atrial fibrillation and low CHADS(2) index treated with catheter ablation therapy. Am. J. Cardiol. 2013; 111 (7): 1002–1011. http://doi.org/10.1016/j.amjcard.2012.12.021
45.Koca H., Demirtas A.O., Kaypakl? O., Icen Y.K., Sahin D.Y., Koca F., Koseoglu Z., Baykan A.O., Guler E.C., Demirtas D., Koc M. Decreased left atrial global longitudinal strain predicts the risk of atrial fibrillation recurrence after cryoablation in paroxysmal atrial fibrillation. J. Interv. Card. Electrophysiol. 2020; 58 (1): 51–59. http://doi.org/10.1007/s10840-019-00573-4
46.Nielsen A.B., Skaarup K.G., Lassen M.C.H., Djern?s K., Hansen M.L., Svendsen J.H., Johannessen A., Hansen J., Sorensen S.K., Gislason G., Biering-Sorensen T. Usefulness of left atrial speckle tracking echocardiography in predicting recurrence of atrial fibrillation after radiofrequency ablation: a systematic review and meta-analysis. Int. J. Cardiovasc. Imaging. 2020; 36 (7): 1293– 1309. http://doi.org/10.1007/s10554-020-01828-2
47.Bajraktari G., Bytyci I., Henein M.Y. Left atrial structure and function predictors of recurrent fibrillation after catheter ablation: a systematic review and meta-analysis. Clin. Physiol. Functional Imaging. 2020; 40 (1): 1–13. http://doi.org/10.1111/cpf.12595
48.Parwani A.S., Morris D.A., Blaschke F., Huemer M., Pieske B., Haverkamp W., Boldt L.H. Left atrial strain predicts recurrence of atrial arrhythmias after catheter ablation of persistent atrial fibrillation. Open Heart. 2017; 28; 4 (1): e000572. http://doi.org/10.1136/openhrt-2016000572
49.Pilichowska-Paszkiet E., Baran J., Kulakowski P., Zaborska B. Echocardiographic assessment of left atrial function for prediction of efficacy of catheter ablation for atrial fibrillation. Medicine. 2021; 100 (38): e27278. http://doi.org/10.1097/MD. 0000000000027278
50.Li Y., Li Y., Sun L., Ye X., Cai Q., Zhu W., Guo D., Ding X., Wang J., Lv X. Left atrial strain for predicting recurrence in patients with non-valvular atrial fibrillation after catheter ablation: a singlecenter two-dimensional speckle tracking retrospective study. BMC Cardiovasc. Disord. 2022; 22 (1): 468. http://doi.org/10.1186/s12872-022-02916-y
51.Nielsen A.B., Skaarup K.G., Djern?s K., Hauser R., San Jose Estepar R., Sorensen S.K., Ruwald M.H., Hansen M.L., Worck R.H., Johannessen A., Hansen J., Biering-Sorensen T. Left atrial contractile strain predicts recurrence of atrial tachyarrhythmia after catheter ablation. Int. J. Cardiol. 2022; 358: 51–57. http://doi.org/10.1016/j.ijcard.2022.04.056
52.Wen S., Indrabhinduwat M., Brady P.A., Pislaru C., Miller F A., Ammash N.M., Nkomo V.T., Padang R., Pislaru S.V., Lin G. Post Procedural Peak Left Atrial Contraction Strain Predicts Recurrence of Arrhythmia after Catheter Ablation of Atrial Fibrillation. Cardiovasc. Ultrasound. 2021; 19 (1): 22. http://doi.org/10.1186/s12947-021-00250-5
53.Yoon Y.E., Oh I.Y., Kim S.A., Park K.H., Kim S.H., Park J.H., Kim J.E., Lee S.P., Kim H.K., Kim Y.J., Sohn D.W., Cho G.Y. Echocardiographic Predictors of Progression to Persistent or Permanent Atrial Fibrillation in Patients with Paroxysmal Atrial Fibrillation (E6P Study). J. Am. Soc. Echocardiogr. 2015; 28 (6): 709–717. http://doi.org/10.1016/j.echo.2015.01.017

The significance of two-dimensional speckle-tracking echocardiography of the left atrium in patients with atrial fibrillation.

This article is a review of the literature devoted to the analysis of promising directions for the use of left atrial strain evaluated using speckle-tracking echocardiography to predict atrial fibrillation (AF). Left atrial strain parameters in various phases of the cardiac cycle are independent predictors of AF both in patients with heart failure and in the general population. The addition of left atrial strain parameters to the traditional echocardiographic parameters will make it possible to effectively select patients with AF both for catheter ablation and to identify patients with a high risk of AF recurrence after catheter ablation.

Keywords:
спекл-трекинг эхокардиография, деформация левого предсердия, фибрилляция предсердий, катетерная абляция, speckle-tracking echocardiography, left atrial strain, atrial fibrillation, catheter ablation