Leadless pacemaker implant, anticoagulation status,
and outcomes: Results from the Micra Transcatheter
Pacing System Post-Approval Registry
Mikhael F. El-Chami, MD, FHRS,* Christophe Garweg, MD, PhD,† Saverio Iacopino, MD,‡
Faisal Al-Samadi, MD, FHRS,x Jose Luis Martinez-Sande, MD,{
~olas Prat, MD,††
Claudio Tondo, MD, PhD, FHRS,k Jens Brock Johansen, MD,** Xavier Vin
Jonathan P. Piccini, MD, MHS, FHRS,‡‡ Yong Mei Cha, MD, FHRS,xx
Eric Grubman, MD, FHRS,{{ Pierre Bordachar, MD, PhD,kk Paul R. Roberts, MD,***
Kyoko Soejima, MD,††† Kurt Stromberg, MS,‡‡‡ Dedra H. Fagan, PhD,‡‡‡
Nicolas Clementy, MD, PhDxxx
From the *Division of Cardiology, Section of Electrophysiology, Emory University, Atlanta, Georgia,
†
Department of Cardiovascular Sciences, UZ Leuven, Leuven, Belgium, ‡Electrophysiology Unit,
Arrhythmology Department, Maria Cecelia Hospital, Cotignola, Italy, xKing Salman Heart
Center–King Fahad Medical City, Riyadh, Saudi Arabia, {Unidad de Arritmias, Servicio de
Cardiologia, University Clinical Hospital of Santiago de Compostela, Santiago de Compostela, Spain,
k
Monzino Cardiac Center, IRCCS, Department of Clinical Sciences and Community, University of
Milan, Milan, Italy, **Department of Cardiology, Odense University Hospital, Odense, Denmark,
††
Arrhythmia Unit, Hospital de la Santa Creu I Sant Pau, Barcelona, Spain, ‡‡Electrophysiology
Section, Duke Center for Atrial Fibrillation, Duke Clinical Research Institute, Duke University Medical
Center, Durham, North Carolina, xxMayo Clinic, Rochester, Minnesota, {{Section of Cardiovascular
Medicine, Yale University School of Medicine, New Haven, Connecticut, kkH^opital Cardiologique du
Haut-Lév^eque, CHU Bordeaux, Université Bordeaux, Bordeaux, France, ***University Hospital
Southampton NHS Foundation Trust, Southampton, United Kingdom, †††Kyorin University Hospital,
Tokyo, Japan, ‡‡‡Medtronic, Inc., Mounds View, Minnesota, and xxxDepartment of Cardiologic
Medicine, Centre Hospitalier Régional Universitaire de Tours–H^opital Trousseau, Tours, France.
BACKGROUND Early results from the Micra investigational trial and
Micra Post-Approval Registry (PAR) demonstrated excellent safety
and device performance; however, outcomes based on anticoagulation (AC) status at implant have not been evaluated.
OBJECTIVE The purpose of this study was to report implant characteristics, perforation rate, and vascular-related events based on
perioperative oral AC strategy in patients undergoing Micra implant.
METHODS We compared procedure characteristics, major complications, and vascular events, including pericardial effusion, stratified
by any adverse event (including major complications, minor compli-
Funding Sources: Dr Piccini was supported by Grant R01HL128595 from the National Heart, Lung, and Blood Institute. Disclosures: The Micra PostApproval Registry (ClinicalTrials.gov Identifier NCT02536118) is funded by Medtronic, Inc. Dr El-Chami reports consulting for Medtronic, Boston Scientific,
and Biotronik. Dr Garweg reports research funding and speaker/consultancy fees from Medtronic. Dr Tondo reports honoraria from Abbott; and serving on the
advisory board of Medtronic and Boston Scientific. Dr Johansen reports serving on a speakers bureau for Medtronic and Merit Medical; and honoraria/scientific
board for Medtronic and Biotronik. Dr Piccini reports clinical research grants from Abbott, American Heart Association, Association for the Advancement of
Medical Instrumentation, Bayer, Boston Scientific, and Philips; and consulting for Abbott, Allergan, ARCA Biopharma, Biotronik, Boston Scientific, LivaNova,
Medtronic, Milestone, MyoKardia, Sanofi, Philips, and Up-to-Date. Dr Roberts reports honoraria from Medtronic. Dr Soejima reports honoraria/lecturing for
Medtronic Japan and Abbott Japan. Dr Stromberg is an employee/shareholder of Medtronic. Dr Fagan is an employee/shareholder of Medtronic. Dr Clementy
reports consulting for Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Address reprint
requests and correspondence: Dr Mikhael F. El-Chami, Division of Cardiology, Section of Electrophysiology, Emory University Hospital, 550 Peachtree St
NE, Atlanta, GA 30308. E-mail address: melcham@emory.edu.
1547-5271/$-see front matter © 2021 Heart Rhythm Society. All rights reserved.
https://doi.org/10.1016/j.hrthm.2021.10.023
El-Chami et al
Anticoagulation Status and Outcomes of Leadless Pacemaker Implant
cations, and observations) or major complication only according to
AC status in the Micra PAR.
RESULTS Among 1795 patients with AC status available, 585 were
not on AC, 795 had AC interrupted, and 415 had AC continued during Micra implant. Non-AC patients tended to be younger, with less
history of atrial fibrillation and chronic obstructive pulmonary disease, and more history of dialysis than interrupted and continued
patients. The implant success rate was similar for all groups
(99.1%–99.8%). Through 30 days postimplant, the overall major
complication rate was 3.1% for the non-AC group, 2.6% for the
interrupted group, and 1.5% for the continued group. The combined
rate for any vascular or pericardial effusion adverse event did not
Introduction
Patients undergoing electrophysiological procedures often
have comorbidities that require chronic anticoagulation
(AC) therapy.1 Interruption of AC before these procedures
is no longer a common practice; rather, performing these procedures with uninterrupted AC is considered the standard of
care in many situations.1–3 For example, performing atrial
fibrillation (AF) ablation without interrupting direct oral
anticoagulants (DOACs) or warfarin has been shown to be
safe and to be associated with fewer embolic events.4–6
Similarly, the practice of implanting a cardiac implantable
electronic device without interrupting DOACs or warfarin
has been shown to be safe in selected patients.1,3
The MicraÔ transcatheter pacing system (Medtronic, Inc.,
Minneapolis, MN) is a novel single-lead pacemaker often implanted in patients with AF and indications for AC.7,8 Implanting Micra requires large-bore venous access and
navigation of the delivery system in the right ventricle to
implant the device.9 Hence, venous access complications
and cardiac perforation are 2 potentially important complications of this procedure similar to what is encountered with
other electrophysiological procedures.8 Two small, retrospective, single-center studies showed that implanting Micra
without interruption of AC can be performed safely.10,11
We sought to assess the safety of implanting Micra in patients enrolled in a multicenter study without interruption of
their chronic AC.
Methods
Study design
Patients undergoing Micra VR implant attempt who were
enrolled in the Micra Post-Approval Registry (PAR) were
included in this analysis.8 The Micra PAR inclusion and
exclusion criteria in addition to a detailed description of
this registry have been reported previously.8,12 In brief, the
Micra PAR is a prospective, nonrandomized, registry study
that enrolled patients with class I or II indications for pacing13
with no comorbidity restrictions. The institutional review
board from each participating institution approved the protocol. The aim of the Micra PAR is to evaluate the safety and
long-term performance of the Micra system when used as intended in “real-world” practice. Therefore, the perioperative
229
differ significantly among AC strategies (6.5%, 4.8%, and 3.6%,
respectively).
CONCLUSION Implant of Micra seems to be safe and feasible
regardless of an interrupted or continued periprocedural oral AC
strategy, with no increased risk of perforation or vascular complications.
KEYWORDS Anticoagulation; Bradycardia; Leadless pacemaker;
Pacing; Vascular complications
(Heart Rhythm 2022;19:228–234)
All rights reserved.
© 2021 Heart Rhythm Society.
oral AC strategy was left to the discretion of the treating
physician. Initial results of the PAR were published and
confirmed the safety and efficacy of the Micra system in a
large patient population.8 The 9-year follow-up period in
the Micra PAR is ongoing.
Baseline demographics, comorbidities, procedural characteristics (including perioperative AC strategy), and study outcomes were collected on study case report forms. Device
diagnostic data contained in interrogation files were obtained
from study centers as they occurred.
Objective
The objective of this analysis was to compare the acute safety
and performance of the Micra system by perioperative oral
AC strategy. For the purposes of this analysis, patients
were divided into 3 groups based on their perioperative
chronic AC strategy as follows: group 1: patients not on
AC; group 2: patients who interrupted AC in the perioperative setting; and group 3: patients who continued AC in the
perioperative setting.
Acute safety was assessed by comparing the rate of any
vascular events (see Supplemental Table S1 for included
events) and pericardial effusion events occurring within 30
days of implant attempt regardless of event severity and by
comparing the subset of these events resulting in major
complication. Major complications were defined as events
related to the Micra system or procedure that resulted in
death, permanent loss of device function, hospitalization,
prolonged hospitalization by 48 hours, or system revision
(Supplemental Table S2).
Statistical analysis
All patients enrolled in the Micra PAR for whom AC status
was reported were included in the analysis. The Micra PAR
database was frozen for this analysis on February 2, 2021.
Baseline characteristics, comorbidities, and procedural characteristics were compared between groups 1 and 2 and between groups 1 and 3 using Student t tests or the Wilcoxon
rank sum test for continuous variables or Fisher exact test
for categorical variables. Logistic regression using Firth
penalized likelihood to account for low event rates was
used to compare the rate of vascular and pericardial effusion
230
Table 1
Heart Rhythm, Vol 19, No 2, February 2022
Baseline and medical history characteristics by oral AC strategy
Patient characteristic
Age (y)
Mean 6 SD
Median
25th–75th percentile
BMI (kg/m2)
Mean 6 SD
Median
25th–75th percentile
BMI ,20
Female
Cardiovascular disease history
Atrial fibrillation
Congestive heart failure
Coronary artery disease
Hypertension
MI
Other comorbidities
COPD
Diabetes
Renal dysfunction
Dialysis
Previous CIED
Preclusion for transvenous system
Pacing indication
Bradyarrhythmia with AF
Sinus nodal dysfunction
AV block
Syncope
Other
Group 1 (no AC)
(n 5 585)
Group 2 (interrupted AC)
(n 5 795)
Group 3 (continuous AC)
(n 5 415)
71.5 6 17.8
76.0
65.0–84.0
77.5 6 9.7
79.0
73.0–84.0
77.8 6 10.8
80.0
74.0–85.0
27.7 6 6.1
26.7
23.8–30.8
5.5% (31/568)
41.4% (242/585)
27.8 6 5.7
26.7
24.2–30.3
3.6% (28/783)
38.3% (304/794)
27.5 6 5.5
26.6
23.9–30.3
4.7% (19/405)
36.1% (150/415)
38.3% (224/585)
11.3% (66/585)
22.1% (129/585)
61.4% (359/585)
7.5% (44/585)
88.5% (703/794)
13.5% (107/794)
22.9% (182/794)
65.6% (521/794)
8.3% (66/794)
6.8% (40/585)
28.5% (167/585)
24.1% (141/585)
12.1% (71/585)
16.9% (99/585)
31.6% (185/585)
34.1% (199/583)
15.3% (89/583)
24.9% (145/583)
22.0% (128/583)
3.8% (22/583)
P value*
P value†
,.001
,.001
.94
.54
.11
.27
.66
.10
85.1% (353/415)
15.2% (63/415)
20.7% (86/415)
68.0% (282/415)
7.5% (31/415)
,.001
.25
.74
.11
.62
,.001
.08
.64
.038
1
11.0% (87/794)
24.9% (198/794)
20.2% (160/794)
5.7% (45/794)
13.9% (110/794)
20.4% (162/795)
11.8% (49/415)
27.0% (112/415)
20.7% (86/415)
6.3% (26/415)
14.9% (62/415)
20.0% (83/415)
.011
.14
.09
,.001
.13
,.001
.009
.62
.22
.002
.43
,.001
76.5% (606/792)
7.1% (56/792)
4.7% (37/792)
9.8% (78/792)
1.9% (15/792)
76.1% (316/415)
6.5% (27/415)
6.5% (27/415)
8.2% (34/415)
2.7% (11/415)
,.001
,.001
AC 5 anticoagulation; AF 5 atrial fibrillation; AV 5 atrioventricular; BMI 5 body mass index; CIED 5 cardiac implantable electronic device; COPD 5 chronic
obstructive pulmonary disease; MI 5 myocardial infarction.
*P value for comparison between groups 1 and 2.
†
P value for comparison between groups 1 and 3.
events and major complications by AC status. Similar models
were used to investigate the event rate and major complication rate by AC status by intravenous (IV) AC use during
the procedure (yes vs no) and within perioperative antiplatelet management strategy (none, discontinued, or continued).
For each comparison, if the omnibus test indicated a difference at the .05 significance level in the outcome between
any 2 AC strategies, pairwise comparisons were performed.
As a sensitivity analysis, logistic regression models using
propensity score overlap weights were used to adjust for differences in baseline and comorbid conditions between AC
groups. To compute the propensity score, the probability of
each patient to receive each AC strategy was estimated using
a multinomial regression model that included the baseline
and comorbidities shown in Supplemental Figure S1. The resulting propensity scores were used to derive a weight for
each patient to adjust for patient differences between AC status. Analyses using propensity score overlap weights place
the most emphasis on patients with characteristics most likely
to be in any of the 3 groups.14 Maximum pairwise standardized mean differences were used to assess balance among covariates included in the propensity model following
weighting.
All analyses were performed using SAS Version 9.4 (SAS
Institute, Cary, NC) or R Version 4.0.2 (www.r-project.org).
Multiple group propensity score weighting was accomplished using PSweight package in R Version 1.1.4 (cran.rproject.org).
Results
Baseline and implant characteristics
A total of 1811 patients were enrolled in the registry, and data
on AC status were available for 1795 patients. The 16 patients with unknown AC status were excluded from subsequent analysis. Of the 1795 patients, 585 (32.6%) were not
on AC (group 1), 795 (44.3%) were on AC but had it interrupted during the perioperative period (group 2), and 415
(23.1%) continued AC during the perioperative period
(group 3). Baseline characteristics and comorbid conditions
are summarized in Table 1. Patients in group 1 (no AC)
were younger on average than those in groups 2 and 3
(71.5 6 17.8 vs 77.5 6 9.7 vs 77.8 6 10.8 years; all P
,.001); were less likely to have a history of AF (38.3% vs
88.5% vs 85.1%; all P ,.001), and were less likely to have
a history of chronic obstructive pulmonary disease (COPD)
El-Chami et al
Table 2
Anticoagulation Status and Outcomes of Leadless Pacemaker Implant
231
Procedural information by oral AC strategy
Patient characteristic
Days hospitalized after implant
Mean 6 SD
Median
25th–75th percentile
n with measure available
Procedural duration (min)
Mean 6 SD
Median
25th–75th percentile
n with measure available
Fluoroscopic duration (min)
Mean 6 SD
Median
25th–75th percentile
n with measure available
Implant success
3 Deployments
Intraprocedure anticoagulation
IV anticoagulation
Reversal agent
Interoperative antiplatelet strategy
No antiplatelet therapy
Discontinued antiplatelet therapy
Continued antiplatelet therapy
Wound closure‡
Manual pressure/bandage
Suture
Closure device
Other
Group 1 (no AC)
(n 5 585)
Group 2 (interrupted AC)
(n 5 795)
Group 3 (continuous AC)
(n 5 415)
4.7 6 32.0
1.0
1.0–2.0
579 (99.0%)
2.6 6 5.3
1.0
1.0–2.0
786 (98.9%)
29.9 6 20.1
25.0
17.0–36.0
509 (87.0%)
P value*
P value†
2.9 6 5.1
1.0
1.0–2.0
414 (99.8%)
.51
.80
34.4 6 30.6
27.0
20.0–40.0
711 (89.4%)
33.5 6 21.7
29.0
20.0–42.0
381 (91.8%)
,.001
.001
10.6 6 43.7
6.2
4.1–10.8
563 (96.2%)
99.1% (580/585)
91.5% (498/544)
14.3 6 74.0
7.2
4.5–11.9
764 (96.1%)
99.1% (788/795)
90.1% (665/738)
9.6 6 22.3
6.0
4.0–10.1
390 (94.0%)
99.8% (414/415)
88.8% (348/392)
1
.44
.41
.18
77.4% (452/584)
11.4% (66/581)
76.7% (610/795)
11.0% (87/788)
80.2% (332/414)
11.7% (48/411)
.80
.86
.31
.92
64.9% (324/499)
13.6% (68/499)
21.4% (107/499)
76.6% (516/674)
16.2% (109/674)
7.3% (49/674)
73.0% (235/322)
5.3% (17/322)
21.7% (70/322)
,.001
,.001
56.3% (327/581)
82.3% (478/581)
2.9% (17/581)
0.0% (0/581)
51.7% (406/785)
83.8% (658/785)
8.4% (66/785)
0.1% (1/785)
44.2% (183/414)
89.9% (372/414)
2.7% (11/414)
0.0% (0/414)
.10
.47
,.001
1
,.001
.001
.85
1
.007
.57
AC 5 anticoagulation.
*P value for comparison between groups 1 and 2.
†
P value for comparison between groups 1 and 3.
‡
Wound closure methods are not mutually exclusive.
(6.8% vs 11.0% vs 11.8%; group 1 vs 2: P 5 .001; group 1 vs
3: P 5 .009). Notably, more group 1 patients tended to
require dialysis and have a preclusion from transvenous pacing compared to group 2 or group 3 patients. Fewer patients
in group 1 had a primary pacing indication associated with
AF compared to group 2 or group 3 patients.
Implant procedure information is summarized in Table 2.
Implant success exceeded 99% in all 3 groups. However,
procedural duration tended to be longer for groups 2 and 3
relative to group 1 (group 1 vs 2 vs 3: median 25.0 vs
27.0 vs 29.0 minutes; all P ,.01), with median fluoroscopic
duration being longest in group 2 (7.2 minutes). Use of IV
AC (77.8%) or reversal agents (11.3%) did not differ across
oral AC strategies. However, perioperative antiplatelet management was different among groups, with a higher percentage of group 1 patients receiving antiplatelet therapy
compared to group 2 or group 3 patients (35.1% vs 23.4%
vs 27.0%; all P ,.001).
Safety
Table 3 lists the rate of acute major complications within 30
days of the Micra implant procedure by AC strategy. The rate
of acute complications by AC strategy was 3.1%, 2.6%, and
1.5% for group 1, 2, and 3, respectively, and did not differ
(P 5 .29). The most commonly occurring major complication across the 3 groups was pacing issues, which included
elevated thresholds and device capturing issues.
The rates of vascular and pericardial effusion events according to AC strategy are shown in Figure 1A, and the event
summaries are provided in Supplemental Table S1. The combined rate of vascular and pericardial effusion events regardless of severity was 6.5%, 4.8%, and 3.6% for groups 1, 2,
and 3, respectively, with no difference in rate of occurrence
among AC strategies (P 5 .12). There was a significant interaction (P 5 .040) regarding the combined rate of vascular
and pericardial effusion events between AC strategy and IV
AC (primarily heparin) use during the procedure. Specifically, patients in group 2 receiving IV AC during the procedure had a higher event rate than patients not receiving IV AC,
while the opposite was true for group 1 patients
(Supplemental Figure S2A). There was not a significant interaction regarding the combined rate of vascular and pericardial effusion events between AC strategy and antiplatelet
use during the procedure (P 5 .80) (Supplemental
Figure S2B). The rate of pericardial effusion regardless of
severity was 1.2% in group 1, 0.8% in group 2, and 0.5%
in group 3 (P 5 .51). Figure 1B shows the subset of vascular
232
Table 3
Heart Rhythm, Vol 19, No 2, February 2022
Acute major complications by oral AC strategy
Adverse event
Group 1 (no AC)
(n 5 585)
Group 2 (interrupted AC)
(n 5 795)
Group 3 (continuous AC)
(n 5 415)
Omnibus
P value*
Total major complications
Cardiac effusion/perforation
Events at groin puncture site
Thrombosis
Pacing issues†
Cardiac rhythm disorder
Infection
Other‡
19 (18, 3.08)
4 (4, 0.68)
2 (2, 0.34)
0 (0, 0.00)
8 (7, 1.20)
0 (0, 0.00)
1 (1, 0.17)
4 (4, 0.68)
25 (21, 2.64)
2 (2, 0.25)
7 (7, 0.88)
2 (2, 0.25)
8 (8, 1.01)
0 (0, 0.00)
3 (3, 0.38)
3 (3, 0.38)
6 (6, 1.45)
2 (2, 0.48)
1 (1, 0.24)
0 (0, 0.00)
1 (1, 0.24)
1 (1, 0.24)
0 (0, 0.00)
1 (1, 0.24)
.29
.52
.38
.62
.36
.46
.64
.62
Values are given as no. of events (no. of patients, %) unless otherwise indicated.
AC 5 anticoagulation.
*Omnibus P value from logistic regression model comparing whether any 2 groups are different. Pairwise P values were not computed as the omnibus P values were
..10.
†
Includes device loss of capture, undersensing, device dislodgment, and device embolization (see Supplemental Table S1 for details).
‡
Other includes congestive heart failure, acute myocardial infarction, pacemaker syndrome, syncope, and pulmonary edema (see Supplemental Table S2 for details).
and pericardial effusion events that met the major complication definition by AC strategy. The combined rate of vascular
and pericardial effusion events resulting in major complication was 1.2%, 1.5%, and 0.7% for groups 1, 2, and 3, respectively, and did not differ significantly (P 5 .58). Likewise,
the combined rate of major complication did not differ by
IV AC use or antiplatelet use during the procedure by AC
strategy (Supplemental Figures S2C and S2D, respectively).
The rate of major complications resulting from pericardial
effusion ranged from 0.7% in group 1 to 0.3% in group
2 and did not differ significantly across oral AC strategy
(P 5 .52). Of the 8 pericardial effusion events leading to a
major complication, 2 required cardiac surgery (1 in group
1 and 1 in group 2) and ultimately resulted in death (described
below). The remaining 6 pericardial events leading to major
complication resolved after pericardiocentesis.
The weighted analysis balanced the baseline characteristics included in the propensity model in the subset of 1788
patients with all baseline measurements available for constructing the overlap weights (Supplemental Figure S1). After adjustment for baseline patient conditions, there were no
differences in the rate of vascular or pericardial effusion
events regardless of severity (Supplemental Table S3). However, in the adjusted analysis of the subset of vascular or pericardial effusion events leading to major complication, group
2 had a higher rate of vascular major complications compared
to group 3 (adjusted rate of 1.7% vs 0.2%; P 5 .038). All 3
groups had an adjusted rate of pericardial effusion leading to
major complication of 0.4%.
Five procedure-related deaths in the Micra PAR have
been reported previously.8 Three of the deaths occurred in
group 1, and 2 occurred in group 2. Of the 3 deaths in group
1, 1 patient died of a retroperitoneal bleed on the day after an
implant procedure, which also involved a concomitant atrioventricular nodal ablation, 1 patient died after cardiac surgery to resolve a cardiac perforation that occurred during
an unsuccessful implant procedure, and 1 patient died of
pulmonary edema in the setting of severe aortic valve dis-
ease on the day of the procedure. In group 2, 1 patient
died 22 days postimplant from sepsis after cardiac surgery
to resolve a cardiac perforation that occurred during an unsuccessful implant attempt, and 1 patient died the day after
the implant procedure during which the patient became hypotensive. There was no evidence of pericardial effusion or
retroperitoneal bleeding. The death was presumed to be
associated with right ventricular failure, possibly due to
acute infarct.
Discussion
In this large multicenter registry, implantation of Micra
without interruption of AC was not associated with an
increased risk of complications. Importantly, we observed
that the rate of pericardial effusion was similar regardless
of AC strategy, ranging from 1.2% in group 1 to 0.5% in
group 3 (P 5 .12). Moreover, the severity of pericardial effusion was not associated with AC status. Groin complications
were similar among the 3 groups. Finally, it is important to
note that similar results were observed after adjusting for patient characteristics.
Kiani et al10 reported their single-center experience with
Micra implantation with and without AC interruption. The
rate of complications was similar irrespective of AC status
at the time of implant. In that study, 26 patients were implanted without AC interruption, whereas 144 were not anticoagulated at the time of implantation. Similarly, a singlecenter study from Spain examined outcomes after Micra implantation in 107 patients.11 Forty-three patients had Micra
implantation without AC interruption. Bleeding complications were not increased in this group.
From 15% to 35% of patients undergoing transvenous
pacemaker implantation have an indication for chronic
AC.1 This rate is even higher in patients undergoing leadless
pacing implantation.
More than 75% of patients undergoing Micra implantation
had a history of atrial arrhythmias, mostly AF.8 By virtue of
El-Chami et al
Anticoagulation Status and Outcomes of Leadless Pacemaker Implant
233
Figure 1 Acute combined vascular and pericardial effusion events (A) and major complications (B) by oral anticoagulation (AC) strategy. Omnibus P values
from logistic regression model comparing whether any 2 groups are different with respect to rate. A detailed breakdown of the vascular events is given in
Supplemental Table S1.
their age and other comorbidities, almost all of these patients
have an elevated CHA2DS2-VASC score that necessitates
AC. Similarly, 76% of patients undergoing Nanostim leadless pacemaker (St Jude Medical, Saint Paul, MN) implant
had a history of supraventricular arrhythmia, and almost
60% were on AC.15 Implantation of leadless pacemakers is
a relatively new procedure that requires a combination skill
set of a complex ablation and CIED implantation. Because
a majority of these patients are on chronic AC, physicians
must make strategic decisions about perioperative management of AC.
Whereas perioperative bridging with low-molecularweight heparin and heparin have fallen out of favor,1,16,17
interruption of AC could carry a risk of thromboembolic
events in high-risk patients. Therefore, performing this
procedure using a strategy of uninterrupted AC has a potential advantage in selected patients. However, the safety
of this approach has not been studied in the setting of a
large multicenter cohort. In this analysis from the Micra
PAR, we show that performing Micra implant without
interruption of AC is safe in a selected group of patients.
This approach did not carry an increased risk of vascular
events such as groin hematoma or retroperitoneal bleed
and importantly did not increase the risk of cardiac perforation and pericardial effusion. Of note, methods and techniques to prevent access complications, including the use
of vascular ultrasound or micropuncture techniques, are
important to avoid bleeding complications regardless of
AC status.
The use of IV AC did not seem to increase the rate of major vascular and pericardial complications, yet it was associated with an increase in nonmajor vascular/pericardial
complications only in patients with interrupted AC (group
2). These data are somehow reassuring given the lack of association with an increase in major complications with IV
234
heparin; however, judicious use of IV heparin probably is
warranted, especially in patients on AC.
Study limitations
This was not a randomized study, so we cannot rule out that
selection bias influenced the results of this analysis.
However, the baseline characteristics of the patients who
had AC interrupted vs those who continued AC in the perioperative setting were similar. Of interest, the baseline characteristics that are associated with increased perforation risk
(female sex, body mass index, coronary artery disease, and
COPD)7 were similar between groups 1 and 2. However, patients on AC were older and more likely to have COPD
compared to patients not taking AC (group 1). Major complications were similar across the 3 groups, and continuation of
AC did not seem to increase vascular complications or the
risk of pericardial perforation despite applying this strategy
in a sicker cohort. Furthermore, data on the type of AC
(DOAC vs warfarin) and international normalized ratio at
the time of the procedure were not collected as part of this
registry. In the absence of data on the type and extent of
AC, care should be exercised in patients considered to be at
increased risk for perforation.
Conclusion
The overall incidence of vascular and pericardial effusion
complications after Micra implant is low. Implantation of Micra using a strategy of uninterrupted AC seems to be safe, with
no increased risk of vascular or pericardial effusion events
compared to a strategy that relies on interruption of AC.
Appendix
Supplementary data
Supplementary data associated with this article can be found
in the online version at https://doi.org/10.1016/j.hrthm.2
021.10.023.
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