Safety of Conscious Sedation for Transcatheter Aortic Valve Replacement Without an Anesthetist

Abstract: Objectives. To compare the safety of performing transfemoral transcatheter aortic valve replacement (TAVR) under conscious sedation without an anesthetist present (TAVR-NA) vs TAVR performed with an anesthetist supervising sedation (TAVR-A). Background. In almost all United States and European centers, TAVR-A represents the standard of care. There are limited data on the safety of TAVR-NA. Methods. The prospective Mater TAVR database was analyzed. Patients undergoing transfemoral TAVR under conscious sedation were identified and divided into 2 groups, ie, TAVR-NA and TAVR-A. Demographics, procedural characteristics, and clinical outcomes for each group were assessed and compared. Results. From a cohort of 300 patients who underwent transfemoral TAVR under conscious sedation, TAVR-NA and TAVR-A were performed in 85 patients and 215 patients, respectively. Baseline variables were similar except for a higher median Society of Thoracic Surgeons score in the TAVR-NA group vs the TAVR-A group (5.1% vs 4.4% in the TAVR-A group; P=.05). TAVR-A patients had a higher rate of conversion to general anesthesia (4.2% vs 1.2% in the TAVR-NA group; P=.29), with 1 patient in each group requiring conversion to emergency surgery. In-lab and in-hospital complication rates were similar in the TAVR-NA and TAVR-A groups (7.1% vs 6.5% [P=.86] and 8.2% vs 12.1% [P=.34], respectively). The Kaplan-Meier estimate of freedom from mortality and/or stroke at 1 month was comparable between both groups (96.5% vs 97.7%; P=.57). Conclusions. In this modest-sized transfemoral TAVR cohort with a low conversion rate to emergency surgery, TAVR-NA was associated with safety outcomes that were equivalent to TAVR-A. In healthcare systems where access to TAVR may be limited by anesthetic resources, TAVR-NA appears to be a reasonable option to enable the application of this therapy. 

J INVASIVE CARDIOL 2021 February 4 (Ahead of Issue). 

Key words: conscious sedation, general anesthesia, transcatheter aortic valve replacement

The practice of anesthesia for transcatheter aortic valve replacement (TAVR) procedures has undergone significant change over time and varies significantly between regions.¹ In parallel with the increased volumes and clinical experience with TAVR, some regions have shown a move away from general anesthesia (GA) in favor of conscious sedation with local anesthesia.^2,3 In general, centers in the United States and Europe continue to employ an anesthetist to administer and supervise conscious sedation for TAVR procedures.⁴ Based largely on a lack of anesthetic resources, a number of TAVR centers in Ireland (and elsewhere) have evolved to perform TAVR procedures with conscious sedation managed solely by the cardiologist and catheterization team in the absence of an anesthetist. There is a paucity of data demonstrating the safety of this approach, with the major concern being the potential harm arising from a delay when GA becomes necessary during a TAVR procedure to facilitate emergency surgery.⁵ We sought to assess the safety of this strategy at our center by comparing the in-hospital and 30-day clinical outcomes in patients who underwent TAVR with conscious sedation supervised by the catheterization laboratory team (TAVR-NA) vs those undergoing TAVR with conscious sedation supervised by an anesthetist (TAVR-A). 

Methods

Ethical approval for this study was granted by the institutional review board of Mater Misericordiae University Hospital. Patients were identified using the Mater TAVR database, which is a prospective database of all TAVR procedures performed at the Mater Misericordiae University Hospital (MMUH) and Mater Private Hospital (MPH) since the inception of the TAVR program in 2008. A clinical nurse specialist with physician oversight at each site is responsible for entering patient demographics, procedural characteristics, and clinical follow-up. Patients provided written informed consent to have their information included in the database at the time of the procedure.  

Patients were eligible for inclusion in the analysis if they underwent TAVR under conscious sedation, using a fully percutaneous femoral approach. Patients were excluded if GA was used from the start of the procedure or if an alternative access site was used. Eligible patients were subsequently divided into 2 groups, ie, the TAVR-NA group, which included patients who had their sedation directed by the cardiologist and catheterization team, and the TAVR-A group, which included patients who had sedation administered and supervised by an anesthetist. The TAVI-NA group was all treated in the public hospital (MMUH), where a lack of anesthetic resources was the driving force for this practice. The TAVI-A cohort came predominantly from the private hospital (MPH), where anesthetic resources were available. 

The sedation protocol for TAVI-A was at the discretion of the treating anesthetist. The typical sedation protocol for the TAVI-NA group included the administration of a bolus of midazolam (1-2 mg) and fentanyl (50 µg) at the start of the case, followed by repeat 1 mg bolus doses of midazolam to maintain patient comfort. 

Baseline clinical, echocardiographic, and procedural variables were analyzed and compared between the 2 groups. Patient outcomes were also analyzed and compared, including complications arising in the catheterization laboratory, in-hospital complications occurring post procedure, and 30-day freedom from mortality and/or stroke. 

The Society of Thoracic Surgeons (STS) score was used to summarize baseline patient characteristics and estimate mortality for surgical aortic valve replacement at 1 month for each group.⁶ Definitions for background medical conditions are in keeping with the Valve Academic Research Consortium (VARC)-2  criteria, as were standard variable and outcome definitions for TAVR.⁷ A stroke diagnosis was confirmed by the hospital stroke team and was defined as a persistent neurological deficit lasting more than 24 hours. The decision to insert a pacemaker was at the discretion of the primary cardiology consultant and was in keeping with current practice guidelines.⁸

Statistical analysis. Continuous variables are presented as mean ± standard deviation or median with interquartile range (IQR). Independent sample T-testing (parametric data) and Mann-Whitney U-testing (non-parametric data) were performed to assess for significant differences between the 2 groups. Categorical data are presented as frequencies and percentages, and compared using the Chi-square and Fisher’s exact tests. A Kaplan-Meier graph was plotted to assess freedom from mortality and/or stroke at 30 days, and groups were compared using the log-rank test. Statistical significance was defined at a level of α≤.05. All analyses were performed with SPSS Statistics, version 24 (IBM).

Results

During the study period, a total of 487 patients underwent TAVR, with 300 patients meeting the inclusion criteria. TAVR-NA and TAVR-A was performed in 85 and 215 patients, respectively. 

Baseline demographics and procedural characteristics (Table 1). The median calculated STS score was higher in TAVR-NA patients vs TAVR-A (5.1% vs 4.4%, respectively; P=.05). Other demographic variables were similar in the TAVR-NA group vs the TAVR-A group, including median procedure duration (70 minutes [IQR, 50-85 minutes] vs 75 minutes [IQR, 60-90 minutes], respectively; P=.10) and median length of hospital stay (3 days [IQR, 3-4 days] vs 3 days [IQR, 3-5 days], respectively; P=.97). 

In-lab and in-hospital complications. Overall in-lab complication rates were not significantly different between the groups (8.2% in the TAVR-NA group vs 12.1% in the TAVR-A group; P=.34) (Table 2). Similarly, no difference was observed in the rate of overall in-hospital postprocedure complications (7.1% in the TAVR-NA group vs 6.5% in the TAVR-A group; P=.86) (Table 3). There was a non-statistically significant trend toward a higher rate of conversion to GA in the TAVR-A group (4.2% [n = 9] vs 1.2% [n = 1] in the TAVR-NA group; P=.29). The single patient in the TAVR-NA group who required GA underwent emergency surgical repair of an annular rupture and survived. Among the 9 patients in the TAVR-A group who underwent conversion to GA, the most common indication (n = 6) was to facilitate management of excessive patient movement/agitation. The indication in the remaining patients was as follows: management of the airway following emesis (n = 1); as a precaution in a patient with partial annular rupture that was successfully managed conservatively (n = 1); and to allow for vascular surgery to attempt repair of an abdominal aortic rupture in a patient who died in the laboratory (n = 1).  

30-day clinical outcomes. There were no deaths in the TAVR-NA group and 2 deaths in the TAVR-A group (1 intraprocedure death and 1 postprocedure death). Kaplan-Meier estimates of freedom from mortality and/or stroke at 30 days for TAVR-NA and TAVR-A groups were 96.5% and 97.7%, respectively (P=.57) (Figure 1). 

Discussion

This study provides one of the few evaluations of the safety of performing fully percutaneous transfemoral TAVR under conscious sedation without an anesthetist present. In a cohort of 300 patients, no differences in procedural, in-hospital, or 30-day outcomes between patients who had TAVR-NA vs TAVR-A were found. 

Move to “minimalist” sedation. Since the inception of TAVR in the early 2000s, there has been a progressive shift toward a more minimalist approach to anesthesia for the procedure. As experience has grown, conscious sedation for TAVR procedures has been applied with increasing frequency, with data showing this approach to be as safe as GA, and associated with reduced costs and length of hospital stay.^9-11 However, there is significant geographic variation in the application of conscious sedation for TAVR, with rapid adoption in some countries (eg, the United Kingdom and France), and more modest adoption in others (eg, the United States and Germany).^2,3,12,13

When TAVR is performed under conscious sedation, current guidelines and consensus statements from major societies recommend supervision of sedation by an anesthetist.^14,15 The practice of performing TAVR under conscious sedation without an anesthetist present represents a departure from standard practice, but has been reported previously by Israeli and German groups.^16,17 

Safety of TAVR-NA. The primary issue of concern when performing TAVR-NA is the risk posed to the patient if GA is required to deal with a major cardiothoracic or vascular complication that requires surgery. This risk will depend on the conversion rate to GA for these surgical emergencies and the efficiency of systems of care when these emergencies occur. 

The data from contemporary TAVR studies suggest that the conversion rate to GA for surgical emergencies is now very low. A recent analysis of over 18,000 patients in the STS/American College of Cardiology registry reported that conversion to open-heart surgery occurred in 0.6% of patients.¹² Conversion rates to open-heart surgery of 0.8% and 1.4% have also been reported from contemporary German and United Kingdom registries, and a conversion rate for all surgery of 0.5% was reported in a recent French registry.^3,13,18 In the 2 published series of TAVR-NA, albeit involving much smaller sample sizes, there was no conversion to GA in the TAVR-NA cohort (n = 174) in the Israeli series, and a conversion rate to GA of 0.3% (n = 1/292) in the German series. Outcomes in our cohort were consistent with these studies. The single conversion to GA in the TAVR-NA cohort in the current series was required to treat an annular rupture causing pericardial tamponade. This reinforces that the safety of the TAVR-NA strategy is predicated on efficient systems of care to activate anesthetic and surgical support when required during TAVR procedures and may not be generalizable. 

Further evidence of the safety of the TAVR-NA strategy is that despite the TAVR-NA cohort in the current series having a higher STS score compared with the TAVR-A cohort, the overall procedural and in-hospital complication rates were similar in both groups (Tables 2 and 3). This is also consistent with the data from the German and Israeli series.

Future of sedation for TAVR. It is unclear whether the practice of performing TAVR without an anesthetist present will be adopted by other groups. The approach has obvious advantages in terms of resource utilization by eliminating the need for anesthetists in most cases and the potential for improved turnover times in the catheterization laboratory. These considerations likely explain the particular adoption by TAVR centers in the Republic of Ireland and Northern Ireland, where the lack of anesthetists and available catheterization laboratory time is a significant hurdle to delivering TAVR services, particularly in public hospitals. In other locations where such issues may limit the availability of TAVR, the current series provides additional evidence supporting the safety of this strategy.

Study limitations. This non-randomized observational study has a number of limitations. First, despite similar baseline characteristics in the TAVI-NA and TAVI-A groups, the potential for residual confounding cannot be eliminated. The TAVI-NA patients were all treated at a single public hospital, whereas the TAVI-A patients were largely treated at a separate private hospital. Although the primary operators were the same at both hospitals, the potential for unmeasured differences exists. The modest size of the patient cohort and low complication rates within each group may limit our ability to detect significant differences between each group.

Conclusion

In this prospective cohort study of patients undergoing TAVR with or without an anesthetist present, we found a low rate of conversion to GA for open-heart surgery in the TAVR-NA group, and no differences in procedural, in-hospital, or 30-day clinical outcomes between both groups. In circumstances where a lack of anesthetic resources may limit the delivery of TAVR services, this study supports the small number of prior studies that have documented the safety of this strategy. 

Acknowledgments. We are grateful to Barbara Moran, Susan Groarke, and Jaime Byrne for their assistance in data collection and maintaining the Mater TAVR database.

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From the ¹Department of Cardiology, Mater Misericordiae University Hospital, Dublin, Ireland; and ²Department of Cardiology, Mater Private Hospital, Dublin, Ireland.

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 accepted July 8, 2020.

Address for correspondence: Professor Ivan P. Casserly, Department of Cardiology, Mater Misericordiae University Hospital, Dublin 7, Ireland. Email: icasserly@mater.ie