Left Atrial Diverticula: A Rare Non-Pulmonary Vein Trigger for Atrial Fibrillation

Left Atrial Diverticula: A Rare Non-Pulmonary Vein Trigger for Atrial Fibrillation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Left Atrial Diverticula: A Rare Non-Pulmonary Vein Trigger for Atrial Fibrillation Kaushal Patel, Ajitha Virinchipuram Ganesan, Gaurav Patel, Darshan Gandhi, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8435174/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Pulmonary vein isolation (PVI) is the cornerstone of the catheter ablation strategy for atrial fibrillation (AF). However, recurrence of AF despite durable PVI suggests the presence of non–pulmonary vein (non-PV) triggers. Left atrial diverticula (LADs) are common anatomic variants but are rarely arrhythmogenic substrates. No standardized guidelines currently address the management of diverticulum-mediated AF Case presentation We report a 48-year-old man with long-standing persistent atrial fibrillation who remained symptomatic despite multiple electrical cardioversions and catheter ablations with repeated pulmonary vein re-isolation. During a fourth ablation procedure using pulsed-field ablation, high-density electroanatomic mapping revealed a discrete region of preserved voltage on the superior posterior wall of the left atrium. Intracardiac echocardiography demonstrated a corresponding sac-like outpouching consistent with a left atrial diverticulum. Given the thin wall of the diverticulum and its proximity to the esophagus, ablation within the pouch was avoided. Targeted ablation at the ostium of the diverticulum resulted in immediate termination of atrial fibrillation and restoration of sinus rhythm. At the two-month follow-up, the patient remained asymptomatic and had no documented arrhythmia recurrence. Conclusions Left atrial diverticula represent rare but important non-PV triggers of atrial fibrillation, particularly in patients with recurrent arrhythmia despite successful PVI. Multimodal imaging combined with high-density mapping can facilitate identification of these substrates and guide safe, individualized ablation strategies. Further studies are needed to define the prevalence and optimal management of diverticulum-mediated atrial fibrillation. Figures Figure 1 Introduction Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and is triggered predominantly by ectopic activity arising from pulmonary veins (PVs). Accordingly, pulmonary vein isolation (PVI) remains the cornerstone of the AF ablation strategy. According to recent international guidelines (2024 EHRA/HRS/APHRS/LAHRS), additional ablation beyond pulmonary vein isolation should be reserved only when nonpulmonary vein foci are definitively mapped or when they are reproducibly inducible after successful PVI(1). This represents a shift from earlier guidelines (2020 ESC guidelines) that advocate for more extensive ablation in persistent atrial fibrillation (PeAF) and long-standing PeAF, including linear ablation in the left atria, left atrial appendage (LAA) isolation, superior vena cava (SVC) isolation, and targeted ablation of potentially arrhythmogenic atrial sites for cases of non-PVI foci(2). Left atrial diverticula, small, pouch-like outpouchings of the atrial wall, represent uncommon but potentially significant nonpulmonary vein (non-PV) triggers of atrial fibrillation. They are not infrequent, with a prevalence varying up to 35% in patients undergoing cardiac imaging for diverse clinical indications, where they are most often identified as incidental anatomic variants (3)(4). Only a few case reports (e.g., Takayanagi et al. 2024, Sirinvaravong et al. 2024, Tsuji et al. 2024)(5)(6)(7) have described diverticula as arrhythmogenic. No standardized guidelines currently address the management of diverticulum-mediated AF. In this study, we report a case of intractable chronic PeAF in which multiple PVI were ineffective, a meticulous search for a non-PVI trigger led to the finding of LAD, and ablation was performed around the ostium of diverticula, highlighting the importance of multimodal imaging and individualized management strategies when standard PVI fails. Case Presentation We describe a 48-year-old man with hypertension, dyslipidemia, and dilated cardiomyopathy who presented with long-standing persistent atrial fibrillation (PeAF). He was diagnosed with AF in 2020 and underwent 9 electrical cardioversions, after which he was started on antiarrhythmic therapy and anticoagulation. Over subsequent years, he underwent a series of catheter ablations: First ablation (September 2021): Isolation of the left common pulmonary vein and two large right-sided pulmonary veins. Second ablation (October 2022): Reisolation of the right and left superior pulmonary veins, with additional anterior wall ablation between the right and left inferior veins. Third ablation (January 2024): The right upper and anterior left veins were reconnected and successfully reablated. Despite these interventions, the patient continued to experience symptoms of recurrent symptomatic AF, such as palpitations, fatigue, and shortness of breath. In September 2025, a fourth ablation was performed via pulsed-field ablation (PFA). All pulmonary veins and the posterior wall were successfully reisolated. However, during ablation, high-density voltage mapping with an OCTARAY catheter revealed a discrete area of preserved high voltage on the superior posterior wall of the left atrium. Intracardiac echocardiography (ICE) demonstrated a corresponding sac-like outpouching consistent with a left atrial diverticulum. Given the thin wall of the diverticulum and its proximity to the esophagus, ablation within the pouch was deemed high risk and therefore deferred. Instead, energy delivery was limited to the ostium (entry site) of the diverticulum, which resulted in successful termination of AF and restoration of sinus rhythm. At the two-month follow-up, the patient remained asymptomatic, and no recurrence of AF was documented. Discussion We encountered a case of recurrent atrial fibrillation (AF) that persisted despite multiple catheter ablations and pulmonary vein isolation (PVI), suggesting the presence of a nonpulmonary vein (non-PV) trigger. High-density voltage mapping revealed a discrete preserved voltage region corresponding to a left atrial diverticulum (LAD) on intracardiac echocardiography (ICE), indicating an arrhythmogenic focus, which was confirmed by fractionated electrograms within the diverticular pouch. Left atrial diverticula are small outpouchings that project from the atrial cavity( 8 )( 9 ). LADs are considered normal variants and are found in up to 35% of patients undergoing cardiac imaging ( 3 , 4 ). The prevalence of LADs was similar in patients with and without AF ( 3 )( 4 )( 5 ). They often contain myocardial fibers. These myocardial fibers are capable of maintaining electrophysiologic activity, such as abnormal automaticity, triggered activity, and microreentrant circuits that can generate or sustain AF. Only a handful of case reports describe LAD as a trigger for atrial arrhythmias (e.g., Takayanagi et al. 2024, Sirinvaravong et al. 2024, Tsuji et al. 2024) ( 5 , 6 , 7 ). Procedural safety considerations are paramount with respect to ablation of the left atrial diverticulum. The diverticulum has thin walls and lies in close proximity to the esophagus. This anatomy poses a substantial risk of perforation or atrioesophageal fistula if energy is applied within the pouch ( 8 ), ( 10 ). Given these risks, the preferred strategy is to limit energy delivery to the ostium or antral region of the diverticulum, rather than deep inside the sac, whenever feasible. Several case reports (e.g., Takayanagi et al. 2024, Sirinvaravong et al. 2024, Tsuji et al. 2024)( 5 )( 6 )( 7 ) have demonstrated successful termination of atrial arrhythmias by performing ablation at or around the diverticular ostium, leading to good outcomes. In our patient, radiofrequency pulsed-field ablation (PFA) was performed at the ostium, effectively terminating AF without complications, which is consistent with prior reports. Compared with thermal ablation, the use of PFA (a nonthermal energy source) may confer an extra safety margin in such scenarios. PFA causes negligible esophageal injury, essentially minimizing the risk of atrio-esophageal fistula( 8 ). This case also underlines the importance of multimodal imaging and high-density mapping in complex, refractory AF. Preprocedural cardiac CT or MRI can reveal anatomical variants such as diverticula, guiding the procedural plan. Intraprocedural intracardiac echocardiography (ICE) is invaluable for visualizing the diverticular anatomy and assessing its wall thickness and location relative to the esophagus. Concurrently, high-density electroanatomic mapping (using an OCTARAY catheter) allowed us to identify a discrete high-voltage area at the diverticulum, indicating preserved viable myocardium and focal electrical activity. We deliberately refrained from delivering lesions inside the diverticulum, given the risks mentioned above, and instead created a lesion set at its entry site. Notably, current guidelines do not specifically address the management of diverticulum-mediated AF because such cases are rare. Thus, an individualized, case-by-case approach is warranted. Our experience contributes to the growing recognition that non-PV triggers (from the LAA, SVC, or rare sites such as an atrial diverticulum) should be systematically sought in long-standing PeAF patients who do not respond to conventional PVI. When identified, targeting these triggers can significantly improve outcomes, as reflected in our patients’ symptom-free status at follow-up, which mirrors the success in other case reports after LAD entry is targeted. Conclusion LADs are common anatomic variants but are very uncommon causes of atrial fibrillation. This case demonstrated LAD as a hidden trigger for AF that was present despite prior successful ablations. High-density mapping and imaging guided us to pinpoint the diverticular focus and safely isolate it with focal ablation at the ostium. This case also undermines the importance of multimodal imaging (CT, ICE) in revealing atypical arrhythmia substrates. Given that the current evidence is limited to isolated case reports and small series, future multicenter data are needed to define the prevalence of arrhythmogenic LADs and effective ablation strategies. Declarations Funding The authors declare that no funding was received for the conduct of this study or for the preparation of this manuscript. Ethics Approval and Consent to Participate Ethical approval was not required for this study, as it is a case report describing clinical observations obtained during routine medical care, with no experimental intervention. Consent for Publication Written informed consent was obtained from the patient for publication of this case report and any accompanying images or clinical information. Competing Interests The authors declare that they have no competing interests . Availability of Data and Materials All data relevant to this case report are included within the manuscript. Authors’ Contributions All authors contributed to the conception and design of the study. Data collection was performed by the authors. All authors participated in manuscript drafting and critical revision for important intellectual content. All authors read and approved the final manuscript. Acknowledgements Not applicable. References (1) Tzeis, S., Gerstenfeld, E. P., Kalman, J., Saad, E. B., Sepehri Shamloo, A., Andrade, J. G.,… Trines, S. A. (2024). 2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation. EP Europace , 26 (4). https://doi.org/10.1093/europace/euae043 (2) Hindricks, G., Potpara, T., Dagres, N., Arbelo, E., Bax, J. J., Blomström-Lundqvist, C.,… Group, E. S. D. (2020). 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio- Thoracic 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. European Heart Journal , 42 (5), 373-498. https://doi.org/10.1093/eurheartj/ehaa612 (3) De Ponti, R., Lumia, D., Marazzi, R., Mameli, S., Doni, L. A., De Venuto, G.,…Salerno- Uriarte, J. A. (2013). Left atrial diverticula in patients undergoing atrial fibrillation ablation: morphologic analysis and clinical impact. J Cardiovasc Electrophysiol , 24 (11), 1232-1239. https://doi.org/10.1111/jce.12213 (4) Peng, L.-Q., Yu, J.-Q., Yang, Z.-G., Wu, D., Xu, J. -J., Chu, Z.-G.,…Chen, J. (2012). Left Atrial Diverticula in Patients Referred for Radiofrequency Ablation of Atrial Fibrillation. Circulation: Arrhythmia and Electrophysiology , 5 (2), 345-350. https://doi.org/doi:10.1161/CIRCEP .111.965665 (5) Takayanagi, T. (2024). Potential arrhythmic substrate of atrial fibrillation at the left atrial diverticulum. Nagoya J Med Sci , 86 (1), 142-148. https://doi.org/10.18999/nagjms.86.1.142 (6) Sirinvaravong, N., Fenberg, R., VanKoevering, K. K., Malara, M., Salmeron, A. W., Rajpal, S., & Houmsse, M. Ablation of Focal Atrial Tachycardia from a Large Left Atrial Diverticulum Using 3D Printing. (7) Tsuji, T., Hasegawa, K., & Tada, H. (2024). Left atrial diverticulum as a rare but possible origin of a sustained atrial tachycardia: a case report. European Heart Journal , 45 (29), 2679-2679. https://doi.org/10.1093/eurheartj/ehae317 (8) Ekanem, E., Neuzil, P., Reichlin, T., Kautzner, J., van der Voort, P., Jais, P.,…Reddy, V. Y. Safety of pulsed field ablation in more than 17,000 patients with atrial fibrillation in the MANIFEST-17K study. (9) Veen, D., Bruning, T. A., & de Groot, N. M. S. (2020). Left atrial diverticula: Innocent bystanders or wolves in sheep's clothing? J Cardiovasc Electrophysiol , 31 (9), 2484- 2488. https://doi.org/10.1111/jce.14581 (10) Yamaoka, K., Takatsuki, S., Yano, S., Himeno, Y., Yamashita, S., Ibe, S.,…Ieda, M. (2025). Association of a Left Atrial Diverticulum with Adverse Events During Catheter Ablation for Atrial Fibrillation. J Clin Med , 14 (9). https://doi.org/10.3390/jcm14093041 Additional Declarations No competing interests reported. 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Accordingly, pulmonary vein isolation (PVI) remains the cornerstone of the AF ablation strategy. According to recent international guidelines (2024 EHRA/HRS/APHRS/LAHRS), additional ablation beyond pulmonary vein isolation should be reserved only when nonpulmonary vein foci are definitively mapped or when they are reproducibly inducible after successful PVI(1). This represents a shift from earlier guidelines (2020 ESC guidelines) that advocate for more extensive ablation in persistent atrial fibrillation (PeAF) and long-standing PeAF, including linear ablation in the left atria, left atrial appendage (LAA) isolation, superior vena cava (SVC) isolation, and targeted ablation of potentially arrhythmogenic atrial sites for cases of non-PVI foci(2). Left atrial diverticula, small, pouch-like outpouchings of the atrial wall, represent uncommon but potentially significant nonpulmonary vein (non-PV) triggers of atrial fibrillation. They are not infrequent, with a prevalence varying up to 35% in patients undergoing cardiac imaging for diverse clinical indications, where they are most often identified as incidental anatomic variants (3)(4). Only a few case reports (e.g., Takayanagi et al. 2024, Sirinvaravong et al. 2024, Tsuji et al. 2024)(5)(6)(7) have described diverticula as arrhythmogenic. No standardized guidelines currently address the management of diverticulum-mediated AF. In this study, we report a case of intractable chronic PeAF in which multiple PVI were ineffective, a meticulous search for a non-PVI trigger led to the finding of LAD, and ablation was performed around the ostium of diverticula, highlighting the importance of multimodal imaging and individualized management strategies when standard PVI fails.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eWe describe a 48-year-old man with hypertension, dyslipidemia, and dilated cardiomyopathy who presented with long-standing persistent atrial fibrillation (PeAF). He was diagnosed with AF in 2020 and underwent 9 electrical cardioversions, after which he was started on antiarrhythmic therapy and anticoagulation.\u003c/p\u003e\n\u003cp\u003eOver subsequent years, he underwent a series of catheter ablations:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eFirst ablation (September 2021): Isolation of the left common pulmonary vein and two large right-sided pulmonary veins.\u003c/li\u003e\n \u003cli\u003eSecond ablation (October 2022): Reisolation of the right and left superior pulmonary veins, with additional anterior wall ablation between the right and left inferior veins.\u003c/li\u003e\n \u003cli\u003eThird ablation (January 2024): The right upper and anterior left veins were reconnected and successfully reablated.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eDespite these interventions, the patient continued to experience symptoms of recurrent symptomatic AF, such as palpitations, fatigue, and shortness of breath.\u003c/p\u003e\n\u003cp\u003eIn September 2025, a fourth ablation was performed via pulsed-field ablation (PFA). All pulmonary veins and the posterior wall were successfully reisolated. However, during ablation, high-density voltage mapping with an OCTARAY catheter revealed a discrete area of preserved high voltage on the superior posterior wall of the left atrium. Intracardiac echocardiography (ICE) demonstrated a corresponding sac-like outpouching consistent with a left atrial diverticulum.\u003c/p\u003e\n\u003cp\u003eGiven the thin wall of the diverticulum and its proximity to the esophagus, ablation within the pouch was deemed high risk and therefore deferred. Instead, energy delivery was limited to the ostium (entry site) of the diverticulum, which resulted in successful termination of AF and restoration of sinus rhythm.\u003c/p\u003e\n\u003cp\u003eAt the two-month follow-up, the patient remained asymptomatic, and no recurrence of AF was documented.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe encountered a case of recurrent atrial fibrillation (AF) that persisted despite multiple catheter ablations and pulmonary vein isolation (PVI), suggesting the presence of a nonpulmonary vein (non-PV) trigger. High-density voltage mapping revealed a discrete preserved voltage region corresponding to a left atrial diverticulum (LAD) on intracardiac echocardiography (ICE), indicating an arrhythmogenic focus, which was confirmed by fractionated electrograms within the diverticular pouch.\u003c/p\u003e \u003cp\u003eLeft atrial diverticula are small outpouchings that project from the atrial cavity(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e)(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). LADs are considered normal variants and are found in up to 35% of patients undergoing cardiac imaging (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). The prevalence of LADs was similar in patients with and without AF (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e)(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). They often contain myocardial fibers. These myocardial fibers are capable of maintaining electrophysiologic activity, such as abnormal automaticity, triggered activity, and microreentrant circuits that can generate or sustain AF. Only a handful of case reports describe LAD as a trigger for atrial arrhythmias (e.g., Takayanagi et al. 2024, Sirinvaravong et al. 2024, Tsuji et al. 2024) (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eProcedural safety considerations are paramount with respect to ablation of the left atrial diverticulum. The diverticulum has thin walls and lies in close proximity to the esophagus. This anatomy poses a substantial risk of perforation or atrioesophageal fistula if energy is applied within the pouch (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e), (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Given these risks, the preferred strategy is to limit energy delivery to the ostium or antral region of the diverticulum, rather than deep inside the sac, whenever feasible. Several case reports (e.g., Takayanagi et al. 2024, Sirinvaravong et al. 2024, Tsuji et al. 2024)(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e)(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) have demonstrated successful termination of atrial arrhythmias by performing ablation at or around the diverticular ostium, leading to good outcomes. In our patient, radiofrequency pulsed-field ablation (PFA) was performed at the ostium, effectively terminating AF without complications, which is consistent with prior reports. Compared with thermal ablation, the use of PFA (a nonthermal energy source) may confer an extra safety margin in such scenarios. PFA causes negligible esophageal injury, essentially minimizing the risk of atrio-esophageal fistula(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). This case also underlines the importance of multimodal imaging and high-density mapping in complex, refractory AF. Preprocedural cardiac CT or MRI can reveal anatomical variants such as diverticula, guiding the procedural plan. Intraprocedural intracardiac echocardiography (ICE) is invaluable for visualizing the diverticular anatomy and assessing its wall thickness and location relative to the esophagus. Concurrently, high-density electroanatomic mapping (using an OCTARAY catheter) allowed us to identify a discrete high-voltage area at the diverticulum, indicating preserved viable myocardium and focal electrical activity. We deliberately refrained from delivering lesions inside the diverticulum, given the risks mentioned above, and instead created a lesion set at its entry site.\u003c/p\u003e \u003cp\u003eNotably, current guidelines do not specifically address the management of diverticulum-mediated AF because such cases are rare. Thus, an individualized, case-by-case approach is warranted. Our experience contributes to the growing recognition that non-PV triggers (from the LAA, SVC, or rare sites such as an atrial diverticulum) should be systematically sought in long-standing PeAF patients who do not respond to conventional PVI. When identified, targeting these triggers can significantly improve outcomes, as reflected in our patients\u0026rsquo; symptom-free status at follow-up, which mirrors the success in other case reports after LAD entry is targeted.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eLADs are common anatomic variants but are very uncommon causes of atrial fibrillation. This case demonstrated LAD as a hidden trigger for AF that was present despite prior successful ablations. High-density mapping and imaging guided us to pinpoint the diverticular focus and safely isolate it with focal ablation at the ostium. This case also undermines the importance of multimodal imaging (CT, ICE) in revealing atypical arrhythmia substrates. Given that the current evidence is limited to isolated case reports and small series, future multicenter data are needed to define the prevalence of arrhythmogenic LADs and effective ablation strategies.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that \u003cstrong\u003eno funding\u003c/strong\u003e was received for the conduct of this study or for the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval was \u003cstrong\u003enot required\u003c/strong\u003e for this study, as it is a case report describing clinical observations obtained during routine medical care, with no experimental intervention.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWritten informed consent\u003c/strong\u003e was obtained from the patient for publication of this case report and any accompanying images or clinical information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have \u003cstrong\u003eno competing interests\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of Data and Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data relevant to this case report are included within the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the conception and design of the study.\u003cbr\u003e\u0026nbsp;Data collection was performed by the authors.\u003cbr\u003e\u0026nbsp;All authors participated in manuscript drafting and critical revision for important intellectual content.\u003cbr\u003e\u0026nbsp;All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003e(1) Tzeis, S., Gerstenfeld, E. P., Kalman, J., Saad, E. B., Sepehri Shamloo, A., Andrade, J. G.,\u0026hellip;\u003c/p\u003e\n\u003cp\u003eTrines, S. A. (2024). 2024 European Heart Rhythm Association/Heart Rhythm\u003c/p\u003e\n\u003cp\u003eSociety/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society\u003c/p\u003e\n\u003cp\u003eexpert consensus statement on catheter and surgical ablation of atrial fibrillation. \u003cem\u003eEP\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEuropace\u003c/em\u003e,\u003cem\u003e\u0026nbsp;26\u003c/em\u003e(4). https://doi.org/10.1093/europace/euae043\u003c/p\u003e\n\u003cp\u003e(2) Hindricks, G., Potpara, T., Dagres, N., Arbelo, E., Bax, J. J., Blomstr\u0026ouml;m-Lundqvist, C.,\u0026hellip;\u003c/p\u003e\n\u003cp\u003eGroup, E. S. D. (2020). 2020 ESC Guidelines for the diagnosis and management of\u003c/p\u003e\n\u003cp\u003eatrial fibrillation developed in collaboration with the European Association for Cardio-\u003c/p\u003e\n\u003cp\u003eThoracic Surgery (EACTS): The Task Force for the diagnosis and management of\u003c/p\u003e\n\u003cp\u003eatrial fibrillation of the European Society of Cardiology (ESC) Developed with the\u003c/p\u003e\n\u003cp\u003especial contribution of the European Heart Rhythm Association (EHRA) of the ESC.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEuropean Heart Journal\u003c/em\u003e,\u003cem\u003e\u0026nbsp;42\u003c/em\u003e(5), 373-498. https://doi.org/10.1093/eurheartj/ehaa612\u003c/p\u003e\n\u003cp\u003e(3) De Ponti, R., Lumia, D., Marazzi, R., Mameli, S., Doni, L. A., De Venuto, G.,\u0026hellip;Salerno-\u003c/p\u003e\n\u003cp\u003eUriarte, J. A. (2013). Left atrial diverticula in patients undergoing atrial fibrillation\u003c/p\u003e\n\u003cp\u003eablation: morphologic analysis and clinical impact. \u003cem\u003eJ Cardiovasc Electrophysiol\u003c/em\u003e,\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e24\u003c/em\u003e(11), 1232-1239. https://doi.org/10.1111/jce.12213\u003c/p\u003e\n\u003cp\u003e(4) Peng, L.-Q., Yu, J.-Q., Yang, Z.-G., Wu, D., Xu, J.\u003c/p\u003e\n\u003cp\u003e-J., Chu, Z.-G.,\u0026hellip;Chen, J. (2012). Left Atrial Diverticula in Patients Referred for Radiofrequency Ablation of Atrial Fibrillation.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCirculation: Arrhythmia and Electrophysiology\u003c/em\u003e,\u003cem\u003e\u0026nbsp;5\u003c/em\u003e(2), 345-350.\u003c/p\u003e\n\u003cp\u003ehttps://doi.org/doi:10.1161/CIRCEP .111.965665\u003c/p\u003e\n\u003cp\u003e(5) Takayanagi, T. (2024). 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Left atrial diverticulum as a rare but possible\u003c/p\u003e\n\u003cp\u003eorigin of a sustained atrial tachycardia: a case report. \u003cem\u003eEuropean Heart Journal\u003c/em\u003e,\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e45\u003c/em\u003e(29), 2679-2679. https://doi.org/10.1093/eurheartj/ehae317\u003c/p\u003e\n\u003cp\u003e(8) Ekanem, E., Neuzil, P., Reichlin, T., Kautzner, J., van der Voort, P., Jais, P.,\u0026hellip;Reddy, V. Y.\u003c/p\u003e\n\u003cp\u003eSafety of pulsed field ablation in more than 17,000 patients with atrial fibrillation in\u003c/p\u003e\n\u003cp\u003ethe MANIFEST-17K study.\u003c/p\u003e\n\u003cp\u003e(9) Veen, D., Bruning, T. A., \u0026amp; de Groot, N. M. S. (2020). Left atrial diverticula: Innocent\u003c/p\u003e\n\u003cp\u003ebystanders or wolves in sheep\u0026apos;s clothing? \u003cem\u003eJ Cardiovasc Electrophysiol\u003c/em\u003e,\u003cem\u003e\u0026nbsp;31\u003c/em\u003e(9), 2484-\u003c/p\u003e\n\u003cp\u003e2488. https://doi.org/10.1111/jce.14581\u003c/p\u003e\n\u003cp\u003e(10) Yamaoka, K., Takatsuki, S., Yano, S., Himeno, Y., Yamashita, S., Ibe, S.,\u0026hellip;Ieda, M. (2025).\u003c/p\u003e\n\u003cp\u003eAssociation of a Left Atrial Diverticulum with Adverse Events During Catheter\u003c/p\u003e\n\u003cp\u003eAblation for Atrial Fibrillation. \u003cem\u003eJ Clin Med\u003c/em\u003e,\u003cem\u003e\u0026nbsp;14\u003c/em\u003e(9).\u003c/p\u003e\n\u003cp\u003ehttps://doi.org/10.3390/jcm14093041\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8435174/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8435174/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePulmonary vein isolation (PVI) is the cornerstone of the catheter ablation strategy for atrial fibrillation (AF). However, recurrence of AF despite durable PVI suggests the presence of non\u0026ndash;pulmonary vein (non-PV) triggers. Left atrial diverticula (LADs) are common anatomic variants but are rarely arrhythmogenic substrates. No standardized guidelines currently address the management of diverticulum-mediated AF\u003c/p\u003e\u003ch2\u003eCase presentation\u003c/h2\u003e \u003cp\u003eWe report a 48-year-old man with long-standing persistent atrial fibrillation who remained symptomatic despite multiple electrical cardioversions and catheter ablations with repeated pulmonary vein re-isolation. During a fourth ablation procedure using pulsed-field ablation, high-density electroanatomic mapping revealed a discrete region of preserved voltage on the superior posterior wall of the left atrium. Intracardiac echocardiography demonstrated a corresponding sac-like outpouching consistent with a left atrial diverticulum. Given the thin wall of the diverticulum and its proximity to the esophagus, ablation within the pouch was avoided. Targeted ablation at the ostium of the diverticulum resulted in immediate termination of atrial fibrillation and restoration of sinus rhythm. At the two-month follow-up, the patient remained asymptomatic and had no documented arrhythmia recurrence.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eLeft atrial diverticula represent rare but important non-PV triggers of atrial fibrillation, particularly in patients with recurrent arrhythmia despite successful PVI. Multimodal imaging combined with high-density mapping can facilitate identification of these substrates and guide safe, individualized ablation strategies. Further studies are needed to define the prevalence and optimal management of diverticulum-mediated atrial fibrillation.\u003c/p\u003e","manuscriptTitle":"Left Atrial Diverticula: A Rare Non-Pulmonary Vein Trigger for Atrial Fibrillation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-11 06:27:41","doi":"10.21203/rs.3.rs-8435174/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1aa86f09-cd5b-4383-a6b8-654cd725c895","owner":[],"postedDate":"February 11th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-26T07:42:52+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-11 06:27:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8435174","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8435174","identity":"rs-8435174","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}