Evaluation of Effectiveness and Safety of Left Atrial Appendage Closure Under Moderate Conscious Sedation

Abstract: Background. Left atrial appendage closure (LAAC) using the Watchman device has become a well-established, world-wide therapeutic alternative to oral anticoagulation in high-risk patients for bleeding with paroxysmal, persistent atrial fibrillation (Afib) or permanent Afib. Currently, in the United States, LAAC procedures are performed under general anesthesia (GA). We present the feasibility, effectiveness, and safety of LAAC under moderate conscious sedation (MCS). Methods. A total of 112 patients with elevated CHA₂DS₂VASc (median score of 3) between November 2018 and November 2019 underwent transesophageal echocardiography (TEE)-guided LAAC with the FDA-approved Watchman LAAC device (Boston Scientific) under MCS. We prospectively evaluated clinical and procedural outcomes using medical records of these patients. Results. Mean patient age was 73.5 ± 4.5 years and 45 (40%) were women. Procedural duration, device implant time, and fluoroscopic times were 45 ± 8.6 minutes, 14.5 ± 2.8 minutes, and 10.2 ± 1.2 minutes, respectively. The median required dosage of propofol was 101 ± 2.8 mg. No complications were observed from MCS. There was no need for conversion to GA in any of the patients during the procedure. Conclusions. LAAC is safe and effective when performed under MCS. Thus, applying MCS may simplify the LAAC procedure, as well as reduce procedural time and procedural costs, while increasing overall patient satisfaction. 

J INVASIVE CARDIOL 2020;32(9):358-362. Epub 2020 June 8.

Key words: anesthesia, conscious sedation, left atrial appendage closure, transcatheter

Atrial fibrillation (Afib) remains one of the most common cardiac arrhythmias and its incidence increases with age. Afib is associated with cardioembolic strokes in patients with increased comorbidities, and that risk can be calculated with the CHA₂DS₂VASc score. The Watchman (Boston Scientific) is the only Food and Drug Administration (FDA)-approved left atrial appendage closure (LAAC) device for patients with paroxysmal, persistent, or permanent Afib who are at high risk for cardioembolic stroke, but are unable to take chronic oral anticoagulation due to their high risk of bleeding.^1,2 

Most LAAC procedures have been traditionally performed under general anesthesia (GA) in the United States, whereas other percutaneous cardiac procedures, including transcatheter aortic valve replacement (TAVR), are increasingly performed under moderate conscious sedation (MCS) or so-called “monitored anesthesia care” (MAC) or deep sedation (DS).^3-5 Transesophageal echocardiography (TEE) is an essential imaging technique to guide LAAC procedures, and the main reason for GA requirement.^1,2 GA is easily and rapidly administered, with the advantages of complete airway control, patient immobility, operator comfort, analgesia, amnesia, and ability to breath-hold.^1,2 However, GA results in increased overall procedure complexity, time, and cost, as well as possible important and serious complications.^6,7 Furthermore, GA is associated with a mortality risk of 0.03 deaths per 1000 patients.⁷ There is scarce knowledge about the feasibility and safety of MCS in LAAC procedures, and no reported experience from the United States in the literature.^8-10 Thus, we present our experience on the effectiveness, procedural characteristics, and safety of LAAC under MCS.

Methods

Study population and preprocedural evaluation. A total of 112 patients with Afib underwent LAAC with MCS between December 2018 and December 2019. We evaluated the clinical and procedural outcomes using medical records. Every patient was assessed and judged unsuitable for chronic oral anticoagulation by an interdisciplinary heart team of cardiologists (including non-implanting physician) and electrophysiologists. LAAC decision was based on CHA₂DS₂VASc scores and bleeding risks, non-compliance, risk of fall, etc. Patients who had CHA₂DS₂VASc scores >2 were enrolled. All patients gave informed consent to undergo the procedure. Informed consents were performed according to institutional guidelines for this study.

Preprocedural evaluation standards consisted of TEE to determine both the morphology as well as the absence of clot in the LAA. All patients had clinical assessment, a full laboratory work-up, and electrocardiography. All patients were started on anticoagulation (warfarin) 4 weeks prior to the procedure date. At 24 hours prior to the procedure, patients were also started on aspirin. 

LAAC procedure. The LAAC procedure was performed under MCS in all patients under fluoroscopic and TEE guidance. Left atrial pressure was invasively measured (left atrial pressure was kept above 12 mm Hg to ensure full expansion of the LAA for proper device sizing) and recorded in all patients. Selection of the Watchman device size was left to the discretion of the interventionalist upon preprocedural review of the LAA morphology and also the intraprocedural measurements of LAA dimensions. During the procedure, intravenous unfractionated heparin was administered to keep the activated clotting time >250 seconds at all times. Procedural time, device implant time, and fluoroscopy time were calculated. Procedural time was defined as the time from the insertion of the venous sheath to the removal of the device delivery system from the body. Device implant time was defined as the time from transseptal puncture to the absolute LAAC meeting the PASS criteria. Procedural success was defined as optimal device compression with color jet around the device and a complete seal of the LAA. All patients were continued on aspirin and warfarin 45 days post procedure per FDA recommendations. Thereafter, 6 months of 81 mg aspirin and 75 mg of clopidogrel were prescribed, followed by 81 mg of aspirin for life.

Conscious sedation protocol. MCS is a drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation.^11,12 DS is a drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposefully following repeated or painful stimulation. The ability to independently maintain ventilatory function may be impaired in DS.^13,14

All patients are seen and screened for best mode of anesthesia and airway protection by both structural heart disease interventionalist or implanting electrophysiologist as well as anesthesiologist on the day of the procedure. The Mallampati score¹⁵ was obtained during the physical examination of each patient. The score was assessed by asking the patient to open his or her mouth as wide as possible, while protruding the tongue as far as possible. The patient was instructed to not emit sounds during the assessment. A standard I to IV grading system was used: class I = soft palate and entire uvula visible; class II = soft palate and portion of uvula visible; class III = soft palate visible (may include base of uvula); and class IV = soft palate not visible.¹⁶ Patients with class IV score were not deemed as suitable for LAAC under MCS. 

All equipment needed for intubation (laryngoscope including a working battery/light, endotracheal tube of the appropriate sizes, stylet), oropharyngeal airway, suction, medications and reversal agents (flumazenil, naloxone) were supplied. Etomidate was readily available in case of emergent intubation. A Certified Registered Nurse Anesthetist (CRNA) and a nurse were available during the entire procedure. The CRNA and nurse were experienced with patient communication and sedative medication administration during TEE and/or catheterization laboratory procedures. Essentially, the procedure was guided by TEE and fluoroscopy. All patients fasted for at least 8 hours before the procedure and we did not hold the patients’ preprocedural anticoagulation prior to the procedure. All patients were treated with preoperative glycopyrrolate and acetaminophen. Local anesthesia of the groin prior to access was performed with prilocaine. Midazolam and/or fentanyl were administered for anxiolysis/sedation in some cases. Up to 6 puffs of topical anesthetic spray were applied before TEE. After an initial bolus of propofol, TEE was inserted via the face mask (Figure 1).

Intravenous propofol infusion was maintained throughout the LAAC procedure. Arterial blood pressure and non-invasive oxygen saturation were continuously monitored. MCS protocol for LAAC is summarized in Table 1.

Statistical analysis. This was a prospective, descriptive study and statistical analyses were performed using SPSS, version 23 for Windows (SPSS). Distribution of data was assessed using a one-sample Kolmogorov-Smirnov test. Data are demonstrated as mean ± standard deviation for normally distributed continuous variables, median (range) for skew-distributed continuous variables, and frequencies for categorical variables. 

Results

All patients underwent LAAC under MCS with an acute procedural success rate of 100%. Mean age was 73.5 ± 4.5 years, and 45 (40%) were women. The mean left ventricular ejection fraction was 62.9 ± 8.9%. Baseline clinical and demographic features of the study population are presented in Table 2.

Procedural success rate was 100%. Mean procedural duration, device implant time, and fluoroscopic time were 45  ±  8.6 minutes, 14.5 ± 2.8 minutes, and 10.2 ± 1.2 minutes, respectively. The median required dosage of propofol was 101 mg. No complications arose from MCS. There was no need for conversion from MCS to GA in any of the patients during the procedure. Procedural data, outcomes, and complications are shown in Table 3.

Discussion 

LAAC procedure requires the use of TEE for the assessment of LAA anatomy, sizing of the preferred device, and confirmation of optimal immediate positioning of the device. Therefore, GA is generally used to reduce the patients’ pain and discomfort. On the other hand, use of GA increases the complexity and cost of overall LAAC procedures, and has its own set of possible and potentially serious complications. Inhaled anesthetic agents may have transient or permanent cognitive dysfunction, particularly in elderly patients.⁶ Other structural heart interventions, such as transcatheter aortic valve replacement, atrial septal defect closure, and patent foramen ovale closure, can be done under MCS safely and effectively without the need for GA.^3-5,17 There has been a limited number of reports in the literature on performing LAA under MCS, but none from a United States experience.^8-10 

In our study, we demonstrate that LAAC can be safely and effectively performed using MCS with mean doses of 3.0 ± 0.2 mg of intravenous midazolam, 50.2 ± 11 µg of fentanyl, and 101 ± 2.8 mg of propofol. Despite the recommended use of GA in LAAC, there have been few previous reports of LAAC procedures that were performed under MCS. A previously published European survey reported the use of MCS in more than 50% of centers for LAAC procedures in Europe.⁸ However, no details were reported regarding the types of sedative drugs, procedural characteristics and outcomes, or the need for the presence of anesthetists. Another study of 80 patients using MCS with intravenous propofol and midazolam during LAAO procedures has been previously published.⁹ However, details of the sedation procedure, particularly the need for an anesthetist to administer propofol, were not available. In fact, for anesthetists, propofol sedation is generally preferred.¹⁸ Thus, our study is the first in the United States to report the safety, feasibility, and procedural details of LAAC procedures under MCS with intravenous propofol with support from anesthetists. These findings have important implications for the reduction of the overall complexity and costs of this increasingly performed procedure. Postoperatively, patients were awakened early after their procedures in the cardiac catheterization laboratory and were transferred directly to regular telemetry beds rather than going to post anesthesia or critical care, with an average savings of about $3589.68 per patient.

We achieved mean procedural duration of 45 ± 8.6 minutes, device implant time of 14.5 ± 7.8 minutes, and fluoroscopy time of 10.2 ± 1.2 minutes. In contrast, a much longer mean procedural time of 51.5 minutes was reported in another study involving 150 patients who underwent Watchman device implantation under GA.² However, the difference in procedural times may be related to other factors, including operator experience, efficiency of the catheterization laboratory staff, and availability of the heart team.

Intracardiac echocardiography has also been used to guide LAAC device implantation in 10 patients. Ronco et al¹⁹ reported a microtransesophageal echocardiographic probe was used to guide LAAC device implantation under conscious sedation.

Although aspiration pneumonia is a potential complication of MCS, it also occurs during GA or the TEE examination itself.²⁰ No aspiration pneumonia was reported in our patients. Whether aspiration pneumonia occurs more commonly in LAAC procedures under MCS compared with GA will require further investigation in a larger patient population. Also, in our experience in the current study, device deployment was not affected to any significant extent by respiratory motion of the patients under MCS. Therefore, device positioning or movement during positioning has been judged to be unrelated to the use of MCS instead of GA.

Per FDA recommendations and the randomized landmark trials of the Watchman device, all patients were given aspirin and warfarin for 45 days after LAAC. At 45-day follow-up TEE, there was no thrombus or significant peridevice leak in any of our patients. Patients were placed on 6 months of aspirin plus clopidogrel if the TEE revealed no significant residual jet flow around the device;¹ thereafter, lifelong aspirin was prescribed.

Our results may need to be confirmed in a randomized controlled study with a larger patient population. We only used the FDA-approved Watchman device in our study. The levels of pain, discomfort, and satisfaction experienced by the patients were not assessed in this study. Nevertheless, we concluded that LAAC procedures can be performed safely and effectively under MCS instead of GA. Our study suggests that both the complexity and costs of this increasingly performed procedure can be substantially reduced with MCS.

Study limitations. Our study had a limited number of patients. We did not compare results directly with GA or DS. We addressed only the Watchman LAAC system, and our findings in patients with MCS cannot necessarily be transferred to other LAAC systems. Finally, sedation is a continuum and it is not always possible to predict how an individual patient will respond. Hence, practitioners intending to produce a given level of sedation should be able to rescue patients whose level of sedation becomes deeper than initially intended. Individuals administering MCS should be able to rescue patients who enter a state of DS, while those administering DS should be able to rescue patients who enter a state of GA.

Conclusion

LAAC can be performed safely and effectively under MCS. Applying MCS may simplify the LAAC procedure while resulting a shorter procedural time, increased patient satisfaction, and a reduction in overall procedural costs. A structural heart disease team approach that includes the anesthesiology specialists should be applied, with the focus on the patient. This may result in increased patient comfort and satisfaction, reduced cost and morbidity, and a more streamlined patient flow in the cardiac catheterization laboratory. Further large-scale randomized controlled studies are needed to confirm these initial findings regarding MCS use for LAAC.

From the ¹Bahcesehir University, School of Medicine, Istanbul, Turkey; ²HCA Northside Hospital, St. Petersburg, Florida; and ³UT Houston, MD Anderson Cancer Center, Houston, Texas.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted January 15, 2020, accepted January 29, 2020.

Address for correspondence: Mehmet Cilingiroglu, MD, FSCAI, FACC, FESC, FAHA, 11800 Carmel Creek Road, San Diego, CA 92130. Email: cilingiroglumehmet@gmail.com

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