Left Atrial Appendage Occlusion for Persistent Thrombus Preventing Rhythm Control

Abstract

Background

Atrial fibrillation is the most common sustained arrhythmia and a major risk factor for cardioembolic stroke. Left atrial appendage occlusion (LAAO) is an established alternative to long-term anticoagulation in selected patients; however, active left atrial appendage (LAA) thrombus is generally considered a contraindication.

Case Summary

A 69-year-old man with hypertension, hyperlipidemia, newly diagnosed nonvalvular atrial fibrillation, and severe left ventricular systolic dysfunction (ejection fraction 20% to 25%) underwent transesophageal echocardiography (TEE) before cardioversion. A large apical LAA thrombus was identified, preventing cardioversion. Despite 9 months of anticoagulation, with apixaban for 2 months followed by warfarin for 7 months, serial TEEs demonstrated persistent thrombus despite supratherapeutic international normalized ratio values as high as 6.9. Following multidisciplinary evaluation, TEE-guided 27-mm Watchman FLX device was successfully performed without complication allowing direct-current cardioversion to normal sinus rhythm with return to normal ejection fraction.

Discussion

This case highlights the potential role of LAAO in patients when persistent thrombus prevents definitive rhythm control.

Take-Home Messages

Persistent LAA thrombus may remain despite prolonged anticoagulation and can prevent definitive rhythm-control therapy in patients with atrial fibrillation. To recognize persistent LAA thrombus as a barrier to rhythm-control therapy and review the role of LAAO in carefully selected patients with thrombus refractory to anticoagulation.

Visual Summary

History of Presentation

A 69-year-old male nonsmoker with hypertension and hyperlipidemia presented with palpitations and was found to have new-onset atrial fibrillation. Physical examination demonstrated an irregularly irregular rhythm consistent with atrial fibrillation. Transthoracic echocardiography revealed severe global hypokinesis with an estimated left ventricular ejection fraction (LVEF) of 20% to 25%, raising concern for tachycardia-induced cardiomyopathy. Given the severity of left ventricular dysfunction, a rhythm-control strategy with direct-current cardioversion was planned.

Past Medical History

Hypertension.

Hyperlipidemia.

Newly diagnosed nonvalvular atrial fibrillation.

Nonischemic cardiomyopathy with severe left ventricular systolic dysfunction.

Differential Diagnosis

Left atrial appendage (LAA) thrombus secondary to atrial fibrillation.

Left atrial myxoma.

Cardiac neoplasm.

Hypercoagulable disorder.

Echocardiographic artifact.

Investigations

Initial transthoracic echocardiography demonstrated severe global left ventricular systolic dysfunction with an estimated ejection fraction (EF) of 20% to 25%.

Preprocedural transesophageal echocardiography (TEE) demonstrated a large thrombus within the apical portion of the LAA shown in Figure 1. Significant biatrial enlargement was present, and LAA emptying velocity was markedly reduced to <20 cm/s, indicating severe atrial mechanical dysfunction and blood stasis. Because of the presence of thrombus, direct-current cardioversion was deferred because of the risk of systemic embolization.

Figure 1.

Initial Transesophageal Echocardiogram Demonstrating a Large Apical Left Atrial Appendage Thrombus (Red Arrow) With Dense Spontaneous Echocardiographic Contrast

The patient was initiated on apixaban. Repeat TEE 1 month later demonstrated persistent residual thrombus with persistently reduced left ventricular systolic function (EF approximately 25%). A third TEE performed 1 month later demonstrated modest improvement in ventricular function (EF 30% ± 5%), although residual thrombus remained present, and the left atrium remained markedly enlarged.

Subsequent serial TEEs over the following months continued to demonstrate persistent thrombus localized to the apical portion of the appendage, shown in Figure 2. Although the thrombus gradually decreased in size, complete resolution was never achieved. Repeat studies consistently demonstrated marked biatrial enlargement and persistent severe atrial mechanical dysfunction. Left ventricular systolic function remained depressed, ranging from 25% to 30%.

Figure 2.

Follow-Up Transesophageal Echocardiogram Demonstrating Persistent Apical Left Atrial Appendage Thrombus (Red Arrow) Despite Anticoagulation With Warfarin

Because persistent thrombus despite therapeutic anticoagulation, treatment was transitioned from apixaban to warfarin with a target international normalized ratio (INR) of 2.0 to 3.0. Despite approximately 9 months of anticoagulation therapy, serial TEE examinations continued to demonstrate persistent apical LAA thrombus. During this period, multiple supratherapeutic INR values were documented, reaching as high as 6.9, yet complete thrombus resolution was never achieved. Hematology was consulted to evaluate the possibility of an underlying hypercoagulable disorder. Given the patient's age, absence of previous thromboembolic events, lack of a family history suggestive of inherited thrombophilia, and the presence of multiple established risk factors for thrombus formation including atrial fibrillation, severe biatrial enlargement, and markedly reduced LAA emptying velocity, additional thrombophilia testing was not pursued by hematology because results were felt unlikely to alter management.

Management

Persistent thrombus prevented cardioversion and definitive rhythm-control therapy in a patient with severe presumed tachycardia-induced cardiomyopathy. Although serial imaging demonstrated gradual reduction in thrombus burden, complete resolution was never achieved despite prolonged anticoagulation.

Given persistent severe left ventricular dysfunction and inability to pursue cardioversion, the case was reviewed by a multidisciplinary team involving electrophysiology, structural cardiology, and hematology specialists. After discussion of risks and benefits, the decision was made to proceed with left atrial appendage occlusion (LAAO) despite persistent residual thrombus.

Given the presence of persistent distal LAA thrombus, meticulous procedural planning was undertaken to minimize embolic risk. The procedure was performed under continuous and fluoroscopic guidance with minimal contrast used to deploy a Sentinel cerebral embolic protection device via right radial access before transseptal puncture. TEE imaging confirmed that the residual thrombus remained confined to the distal apical portion of the appendage. A versa cross catheter and sheath were advanced into the superior vena cava. The sheath was then pulled back until tenting was noticed of the interatrial septum. After confirming location on ultrasound, the septum was crossed with radiofrequency needle. The wire was then advanced to the left atrium as well as the sheath. The sheath was then pulled back into the right atrium, the intracardiac echocardiography catheter was advanced into the left atrium through the same access site. The sheath was then readvanced into the left atrium. We then took a pigtail and advanced this to the sheath into the left atrium with minimal advancement into the LAA ostium and sizing was performed and a 27-mm Watchman FLX device was successfully implanted with 15% to 25% compression and met PASS criteria. Direct-current cardioversion was subsequently performed after device implantation with restoration of sinus rhythm, and the device was found to have compression between 19% and 26% with stable “tug test.” Finally, a sweep was performed with the intracardiac echocardiographic catheter to ensure no pericardial effusion or dislodgement of thrombus occurred. No procedural complications, neurologic events, or evidence of thrombus embolization occurred. Pre- and postimplantation images are shown in Figures 3 and 4, respectively.

Figure 3.

Preprocedural Transesophageal Echocardiogram Demonstrating Persistent Residual Thrombus Within the Apical Left Atrial Appendage (Red Arrow) Immediately Before Left Atrial Appendage Occlusion

Figure 4.

Follow-Up Transesophageal Echocardiogram Demonstrating Successful Left Atrial Appendage Occlusion Device Implantation With Exclusion of the Appendage Cavity (Red Arrow)

Outcome and Follow-Up

The patient experienced no procedural complications, including stroke, transient ischemic attack, systemic embolization, pericardial effusion, or vascular injury.

At 1-month follow-up, transthoracic echocardiography demonstrated substantial recovery of left ventricular systolic function, and electrocardiogram showed normal sinus rhythm. Left ventricular cavity size and wall thickness were normal, and EF improved to 50% to 55%. This marked improvement supported the diagnosis of tachycardia-induced cardiomyopathy and highlighted the clinical significance of persistent thrombus as a barrier to definitive rhythm-control management.

Discussion

LAA thrombus is a recognized complication of atrial fibrillation and remains the principal source of cardioembolic stroke in patients with nonvalvular atrial fibrillation. Current guidelines recommend anticoagulation for thrombus resolution and generally consider active LAA thrombus a contraindication to LAAO because of concern for thrombus dislodgement during device deployment.^1,2

Several echocardiographic findings likely contributed to thrombus persistence in this patient. Initial TEE demonstrated a large apical LAA thrombus, severe biatrial enlargement, and markedly reduced appendage emptying velocity (<20 cm/s). Reduced LAA emptying velocity is a recognized marker of blood stasis and has been associated with spontaneous echocardiographic contrast, thrombus formation, and thromboembolic events.³ Likewise, severe biatrial enlargement reflects advanced atrial remodeling and impaired mechanical function, both of which may reduce the likelihood of thrombus resolution despite anticoagulation.⁴

Most LAA thrombi resolve after several weeks of uninterrupted anticoagulation. However, persistence despite adequate therapy is increasingly recognized, particularly among patients with severe atrial cardiomyopathy, enlarged atria, reduced appendage emptying velocities, and severe left ventricular dysfunction.⁵ In this patient, serial imaging demonstrated gradual reduction in thrombus burden but failed to achieve complete resolution despite treatment with both a direct oral anticoagulant and warfarin.

An important feature of this case is that even a small residual thrombus continued to preclude cardioversion and definitive rhythm-control therapy. As a result, the patient remained in atrial fibrillation while severe left ventricular dysfunction persisted. The inability to pursue rhythm-control strategies may have delayed recovery from a potentially reversible tachycardia-induced cardiomyopathy.⁶

Although active thrombus remains outside traditional indications for LAAO, emerging reports and case series suggest that carefully selected patients may benefit from device-based therapy when conventional management strategies fail.7, 8, 9 In our patient, the thrombus remained confined to the distal apical portion of the appendage, allowing consideration of device implantation after multidisciplinary discussion among electrophysiology, structural cardiology, and hematology specialists. To mitigate procedural risk, a Sentinel cerebral embolic protection device was deployed before transseptal access, and the procedure was performed under continuous intracardiac echocardiographic and fluoroscopic guidance. Successful implantation of a 27-mm Watchman FLX device was achieved without neurologic or procedural complications.

A particularly notable feature of this case was the marked improvement of left ventricular systolic function from 20% to 25% at presentation to 50% to 55% at 1-month follow-up. Although causality cannot be definitely established, the degree and rapid improvement strongly support tachycardia-induced cardiomyopathy as a major contributor to the patient's diminished EF. This case highlights the clinical consequences of persistent LAA thrombus with underlying tachycardia inhibiting direct-current cardioversion, highlighting LAAO's utility beyond thromboembolic risk alone.⁶

Most previously reported cases of LAAO in the setting of persistent thrombus have focused on stroke prevention when anticoagulation was ineffective or contraindicated. In contrast, our case highlights a distinct therapeutic rationale. LAAO was pursued not simply to reduce future thromboembolic risk, but to remove a barrier preventing definitive rhythm-control therapy. Successful device implantation allowed immediate cardioversion, restoration of sinus rhythm, and subsequent recovery of left ventricular function. This case therefore suggests a potential role for LAAO as a facilitator of rhythm-control therapy in carefully selected patients with persistent LAA thrombus refractory to anticoagulation. Although additional data are needed, this strategy may be particularly relevant in patients whose persistent atrial fibrillation contributes to reversible cardiomyopathy and ongoing heart failure.

Conclusions

Persistent LAA thrombus refractory to prolonged anticoagulation remains a challenging clinical problem. In carefully selected patients with persistent thrombus preventing definitive rhythm-control therapy, LAAO may represent a reasonable treatment strategy following multidisciplinary evaluation.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Take-Home Messages

• •Persistent LAA thrombus may remain despite prolonged anticoagulation and can prevent definitive rhythm-control therapy in patients with atrial fibrillation.
• •To recognize persistent LAA thrombus as a barrier to rhythm-control therapy and review the role of LAAO in carefully selected patients with thrombus refractory to anticoagulation.

Visual Summary.

Timeline of the Case

Date	Events
March 2024	A 69-year-old man presented with palpitations and was found to have new-onset atrial fibrillation. Transthoracic echocardiography demonstrated severe global left ventricular systolic dysfunction with an estimated LVEF of 20%–25%, concerning for tachycardia-induced cardiomyopathy.
March 23, 2024	Transesophageal echocardiography (TEE) performed before planned direct-current cardioversion demonstrated a large thrombus within the apical LAA, severe biatrial enlargement, and markedly reduced LAA emptying velocity (<20 cm/s). Cardioversion was deferred because of thromboembolic risk. Apixaban therapy was initiated.
April 2024	Repeat TEE demonstrated persistent residual LAA thrombus despite anticoagulation. Left ventricular systolic function remained severely reduced (LVEF approximately 25%).
May 28, 2024	Follow-up TEE demonstrated persistent residual thrombus with modest improvement in left ventricular systolic function (LVEF 30% ± 5%). Marked left atrial enlargement persisted. Because of persistent thrombus despite apixaban therapy, anticoagulation was transitioned from apixaban to warfarin (target INR 2.0-3.0).
July 2024	Repeat TEE demonstrated persistent apical thrombus, although thrombus burden appeared reduced compared with prior imaging. LVEF remained approximately 25%.
September 2024	TEE again demonstrated persistent apical thrombus and marked biatrial enlargement. LVEF remained 25%–30%.
May–December 2024	Despite warfarin therapy, serial imaging continued to demonstrate persistent LAA thrombus. Multiple supratherapeutic INR values occurred, reaching as high as 6.9, without complete thrombus resolution. Hematology was consulted and determined that a hypercoagulable evaluation would be low yield and unlikely to alter management.
December 2024	Following multidisciplinary evaluation by electrophysiology, structural cardiology, and hematology specialists, LAAO was recommended because persistent thrombus continued to preclude definitive rhythm-control therapy and recovery from presumed tachycardia-induced cardiomyopathy.
December 11, 2024	Successful implantation of a 27-mm Watchman FLX device was performed under intracardiac echocardiographic and fluoroscopic guidance with Sentinel cerebral embolic protection. The thrombus remained confined to the distal apical appendage. No procedural complications occurred. Direct-current cardioversion restored sinus rhythm.
Postprocedural day 1	Patient was discharged home in stable condition without neurologic or procedural complications.
January 2025 (1-month follow-up)	Transthoracic echocardiography demonstrated marked recovery of left ventricular systolic function with improvement in LVEF from 20%–25% to 50%–55%. The patient remained in normal sinus rhythm and clinically well.
February 5, 2025	Follow-up evaluation demonstrated satisfactory device position without complication. Warfarin was discontinued and dual antiplatelet therapy with aspirin and clopidogrel was initiated.

INR = international normalized ratio; LAA = left atrial appendage; LAAO = left atrial appendage occlusion; LVEF = left ventricular ejection fraction; TEE = transesophageal echocardiography.