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Incidence and predictors of major complications from
contemporary catheter ablation to treat cardiac arrhythmias
Marius Bohnen, BSc, William G. Stevenson, MD, FHRS, Usha B. Tedrow, MD, MSc, FHRS,
Gregory F. Michaud, MD, FHRS, Roy M. John, MD, PhD, FHRS, Laurence M. Epstein, MD, FHRS,
Christine M. Albert, MD, MPH, Bruce A. Koplan, MD, MPH, FHRS
From the Cardiac Arrhythmia Service, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital,
Boston, Massachusetts.
BACKGROUND Updated understanding of the risks of catheter ablation is important because techniques have evolved for procedures
treating non–life-threatening as well as potentially lethal arrhythmias.
OBJECTIVE This prospective study sought to assess the incidence
and predictors of major complications from contemporary catheter
ablation procedures at a high-volume center.
METHODS Over a 2-year period, 1,676 consecutive ablation procedures were prospectively evaluated for major complications throughout 30 days postprocedure. Predictors of major complications were
determined in a multivariate analysis adjusted for demographics,
clinical variables, ablation type, and procedural factors.
RESULTS Rates of major complications differed between procedure types, ranging from 0.8% for supraventricular tachycardia,
3.4% for idiopathic ventricular tachycardia (VT), 5.2% for atrial
fibrillation (AF), and 6.0% for VT associated with structural heart
disease (SHD). Ablation type (ablation for AF [odds ratio (OR)
5.53, 95% confidence interval (CI) 1.81 to 16.83], for VT with SHD
[OR 8.61, 95% CI 2.37 to 31.31], or for idiopathic VT [OR 5.93,
95% CI 1.40 to 25.05] all referenced to supraventricular tachycar-
Introduction
Reported catheter ablation complication rates vary considerably, depending on the type of procedure.1–7 A better
understanding of the procedural risk is important for selecting patients for ablation. In addition, because several reports
on procedural complications have been published many
years ago and technology to improve safety has advanced,
prior results may be outdated. Knowledge of the contemporary major complication rates for catheter ablation is a
necessity in the current health policy climate, as professional organizations and regulatory entities weigh risk and
benefits, relative value, and consider health care quality
issues. We sought to determine the incidence and predictors
Drs. Koplan, Tedrow, Michaud, Epstein, and John serve as consultants to
and receive research support from St. Jude Medical. Dr. Epstein serves as a
consultant to Medtronic, General Electric, and Bard Medical and receives
research support from Medtronic. Dr. Tedrow receives research support from
Biosense Webster/Johnson & Johnson. Address reprint requests and correspondence: Dr. Bruce A. Koplan, Brigham and Women’s Hospital, 75
Francis Street, Boston, MA 02115. E-mail address: [email protected].
(Received April 14, 2011; accepted May 19, 2011.)
dia ablation), and serum creatinine level ⬎1.5 mg/dl (OR 2.48,
95% CI 1.07 to 5.76) were associated with increased adjusted risk
of major complications, whereas age, gender, body mass index,
international normalized ratio level, hypertension, coronary artery
disease, diabetes, and prior cerebrovascular accident were not
associated with increased risk.
CONCLUSION In a large cohort of contemporary catheter ablation, major complication rates ranged between 0.8% and 6.0%
depending on the ablation procedure performed. Aside from ablation type, renal insufficiency was the only independent predictor
of a major complication.
KEYWORDS Atrial fibrillation; Catheter ablation; Outcomes; Quality of care
ABBREVIATIONS AF ⫽ atrial fibrillation; AVNRT ⫽ atrioventricular nodal reentrant tachycardia; CVA ⫽ cerebrovascular accident;
LV ⫽ left ventricle; SHD ⫽ structural heart disease; SVT ⫽ supraventricular tachycardia; VT ⫽ ventricular tachycardia
(Heart Rhythm 2011;8:1661–1666) © 2011 Heart Rhythm Society.
All rights reserved.
of major complications from contemporary catheter ablation
procedures at a high-volume center.
Methods
In this prospective study, all patients undergoing catheter
ablation at our institution were enrolled in an electronic
database at the time of their procedure that included demographic and procedural information, along with all complications through 30 days of follow-up. All procedures from
January 2009 through January 1, 2011, were analyzed. Procedures were classified as either ablation for atrial fibrillation (AF), supraventricular tachycardia (SVT) other than
AF, ventricular tachycardia (VT) associated with structural
heart disease (SHD), or idiopathic VT. The study was reviewed and approved by our institutional review board.
Anticoagulation and postprocedural
management
Patients on long-term anticoagulation therapy were managed with either a bridging strategy with intravenous heparin/subcutaneous enoxaparin or remained on coumadin
1547-5271/$ -see front matter © 2011 Heart Rhythm Society. All rights reserved.
doi:10.1016/j.hrthm.2011.05.017
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Heart Rhythm, Vol 8, No 11, November 2011
through their procedure with a targeted international normalized ratio (INR) of 2.0 to 3.0. During left heart procedures, intravenous heparin was administered to maintain the
activated clotting time over 350 seconds for AF and over
250 seconds for all other ablations.
All patients were assessed for complications before hospital
discharge. Patients also received written and verbal instructions to contact the operating physician regarding any complications or unplanned outside hospital visits. Patients were
routinely evaluated at our outpatient arrhythmia clinic postprocedure. When follow-up in our clinic could not be scheduled
because of logistical issues, information about complication
follow-up was obtained from patients per their written discharge instructions and/or outside following physician.
Definition of outcomes
A major complication was defined as an adverse event related
to the procedure requiring intervention for treatment, causing
long-term disability, or resulting in prolonged hospitalization.7,8 An intervention was counted if it involved an invasive
procedure (e.g., vascular surgery, pericardiocentesis, thrombin
injection) or blood transfusion. Adverse events that only required outpatient drug administration was not considered a
major complication. Arrhythmia recurrence requiring medical
or invasive management was not counted as a complication.
All complications were reviewed, with the members of the
arrhythmia service in a morbidity and mortality meeting and
classified as major or minor. Only major complications were
included in our current analysis.
Table 1
Statistical analysis
Our analysis included all patients entering the electrophysiology laboratory for catheter ablation, regardless of whether
ablation was performed. Continuous variables are summarized as mean ⫾ SD, categorical variables as absolute frequency (percentage). For univariate analysis, an independent t test was used for continuous variables and a ␹2 or
Fisher exact test for categorical variables. Analysis of variance (ANOVA) was used to compare multiple means. To
adjust for differences between groups, multivariate analysis
was performed creating a binary logistic regression model.
All tests were 2-sided, and a P value of ⬍0.05 was considered statistically significant. Statistical analysis was done
with SPSS version 18.0 (SPSS Inc., Chicago, IL).
Results
Patient and procedural characteristics
During the 2-year period, 1,676 consecutive ablation procedures were performed. Table 1 displays baseline demographics. The average age was in the 6th decade, with approximately one-third of the cohort being female. About one-third
of the cohort had a body mass index (BMI) ⱖ30. There was a
reasonable representation of comorbidities, including coronary
artery disease (22.1%), diabetes (15.4%), and abnormal renal
function, reflected by elevated serum creatinine levels of ⬎1.5
mg/dl (6.4%).
Procedures types are also displayed in Table 1. The most
common ablation was for AF (46.8%), with 57.1% parox-
Baseline demographics (n ⫽ 1,676 ablations)
Characteristic
Total
SVT
n ⫽ 524
AF
N ⫽ 784
VT with SHD
n ⫽ 250
Idiopathic VT
n ⫽ 118
Age (y)
Age ⱖ 70
Female
Weight (kg)
BMI
BMI categories
⬍25
25–29.9
ⱖ30
LVEF (%)
LVEF ⱕ30%
Medical history
Hypertension
Coronary artery disease
Diabetes mellitus
Prior CVA
Laboratory values
INR
INR ⱖ2.0
Creatinine (mg/dl)
Creatinine ⬎1.5 mg/dl
Procedure types
SVT ablation
AF ablation
VT ablation with SHD
VT ablation, idiopathic
Procedural factors
Access ⱖ4 sheaths
57.6 ⫾ 14.4
19.0%
34.0%
88.0 ⫾ 20.4
28.7 ⫾ 5.9
54.9 ⫾ 18.2
21.2%
45.2%
81 ⫾ 20.8
27.3 ⫾ 6.1
59.1 ⫾ 10.7
15.8%
28.4%
93.1 ⫾ 19.3
29.6 ⫾ 5.6
62.6 ⫾ 13.0
31.7%
19.7%
87.5 ⫾ 19.1
28.7 ⫾ 6.1
48.8 ⫾ 13.0
4.25%
50.4%
84.4 ⫾ 18.8
28.3 ⫾ 5.9
27.6%
38.4%
33.8%
53.1 ⫾ 13.8
12.9%
41.1%
32.4%
26.5%
56.4 ⫾ 10.6
5.5%
18.1%
42.9%
38.9%
57.5 ⫾ 8.8
4.5%
29.3%
36.9%
33.7%
31.5 ⫾ 13.9
63.1%
28.2%
38.5%
33.3%
54.7 ⫾ 11.4
5.9%
47.5%
22.1%
15.4%
5.6%
42.65%
15.7%
15.1%
4.4%
51.7%
16.1%
12.9%
4.8%
53.0%
60.6%
28.1%
12.4%
30.3%
10.1%
6.7%
1.7%
1.7 ⫾ 0.7
34.2%
1.04 ⫾ 0.5
6.4%
1.4 ⫾ 0.6
18.9%
1.04 ⫾ 0.8
6.8%
2.1 ⫾ 0.6
59.3%
1.0 ⫾ 0.3
3.3%
1.3 ⫾ 0.3
3.6%
1.2 ⫾ 0.6
16.9%
18.5%
71.8%
49.4%
1.1 ⫾ 0.1
0%
0.9 ⫾ 0.2
2.5%
31.3%
46.8%
14.9%
7.1%
49.5%
39.5%
Data displayed as mean ⫾ SD or percentage.
AF ⫽ atrial fibrillation; BMI ⫽ body mass index; CVA ⫽ cerebrovascular accident; INR ⫽ international normalized ratio; LVEF ⫽ left ventricular ejection fraction; SHD ⫽
structural heart disease; SVT ⫽ supraventricular tachycardia; VT ⫽ ventricular tachycardia.
Bohnen et al
Complications From Contemporary Catheter Ablation
ysmal and 42.9% persistent. SVT ablation occurred in
31.3%, of which 26.5% were atrioventricular nodal reentrant tachycardia (AVNRT), 14.3% accessory pathways,
11.5% atrial tachycardia, and 42% right atrial flutter. VT
ablations, either in the presence or absence of SHD, comprised 22.0% of the cohort. Epicardial access was obtained
in 21.3% of VT ablations with SHD.
Patient and procedure characteristics varied among different procedure types. SVT or idiopathic VT ablation patients were younger (55 ⫾ 18 years and 48 ⫾ 13 years,
respectively) than patients undergoing an AF ablation (59 ⫾
11 years) or an ablation for VT in the setting of SHD (63 ⫾
13 years, P ⬍ .01). Prior ablation had occurred in 432
(30.1%) patients. A transseptal approach occurred in 14.7%
of SVT, 10.1% of idiopathic VT, 14.5% of other VT, and all
AF procedures, except 1, which was aborted prematurely
for anatomic reasons. Transseptal puncture utilized intracardiac ultrasound in 85.6% of cases. Epicardial access was
obtained mainly in VT ablation, except for 2 cases of an
accessory pathway and 1 case of atrial tachycardia. A therapeutic INR level on the day of the procedure occurred in
34.2% of patients. Among the 1026 (61.3%) procedures
with the patient being on long-term anticoagulation therapy,
827 (49.3%) patients continued warfarin (INR 2.2 ⫾ 0.5)
throughout their procedure, whereas 198 (11.8%) used a
bridging strategy with intravenous heparin or subcutaneous
enoxaparin (INR 1.4 ⫾ 0.3).
Incidence of major complications
Major complication rates by procedure type are displayed in
Table 2. In our entire cohort, a major complication occurred
in 64 of 1,676 (3.8%) of procedures. The rate was lowest for
SVT (0.8%), and highest for AF (5.2%) and VT ablations in
with SHD (6.0%, P ⬍ .01). In SVT, excluding AF, in which
left heart access was obtained (n ⫽ 76) the rate was 1.3%
(n ⫽ 1 psuedoaneurysm in a retrograde aortic approach).
Table 2
1663
Most complications (35 of 64, 54.7%) occurred on the
procedure day (22 of 64, 31.1% intraoperatively). Postprocedural complications were diagnosed at a mean of 4.4 ⫾
5.6 days, including 2 late pericardial effusions on postprocedural day 5 and 6.
Two (0.1%) patients suffered procedure-related death.
One resulted from intraprocedural embolic stroke during AF
ablation. Postmortem examination revealed an interatrial
septum aneurysm containing chronic thrombus, which was
not seen in the preprocedural TEE. In a second patient with
severe cardiomyopathy and peripheral vascular disease,
who underwent urgent ablation for ischemic VT, death
resulted from complications of retroperitoneal bleed.
The most common major complications were related to
femoral access (1.4%). Pericardial effusion occurred in
1.3%, with tamponade in 0.7%. Each of these complications
was least common in SVT ablation. Access complications
occurred more frequently after ablations for AF and VT
with SHD than SVT (P ⫽ .022 and P ⫽ .016, respectively).
All (14 of 14) perforations in AF ablations were managed
successfully with percutaneous drainage (even with INR
therapeutic at the procedure). In contrast, 4 of 4 patients
suffering a perforation during ablation for VT with SHD
developed tamponade and subsequently required surgical
revision. Two AF procedures were aborted because of pericardial contrast during transseptal puncture. These patients,
however, did not develop a pericardial effusion and did not
meet criteria to be classified as major complication.
There were 11 (0.7%) thromboembolic events: 10 strokes
and 1 peripheral embolus. Thromboembolic events were
higher in AF ablation than SVT (P ⫽ .017). For other ablation
types, thromboembolic rates did not differ from SVT ablation.
Of all thromboembolic events, only 3 (27.3%) were clinically
evident before the patient leaving the procedure room. Two
patients experienced a postablation bleeding complication,
Major complications from catheter ablation procedures
Type of major complication
Total
n ⫽ 1,676
SVT
n ⫽ 524
AF
n ⫽ 784
VT with SHD
n ⫽ 249
Idiopathic VT
n ⫽ 119
Death
Perforation
Tamponade
Pericardial effusion
Thromboembolic event
Stroke/TIA
Systemic embolus
Access complication
Retroperitoneal bleed
Groin hematoma
Pseudoaneurysm
AV fistula
Other complications
Deep vein thrombosis
Aspiration pneumonia
Pulmonary edema
Conduction system damage
Genitourinary trauma
Major complication rate
2
21
12
9
11
10
1
23
5
9
7
2
9
1
3
2
1
2
64
0
1
0
1
0
0
0
2
0
0
2
0
1
0
0
1
0
0
4
1
14
7
7
8
7
1
14
4
6
3
1
5
0
3
0
1
1
41
1
4
4
0
2
2
0
5
1
3
1
1
3
1
0
1
0
1
15
0
2
1
1
1
1
0
1
0
0
1
0
0
0
0
0
0
0
4
(0.1)
(1.3)
(0.7)
(0.5)
(0.7)
(0.6)
(0.1)
(1.4)
(0.3)
(0.5)
(0.4)
(0.1)
(0.5)
(0.1)
(0.2)
(0.1)
(0.1)
(0.1)
(3.8)
(0.2)
(0.2)
(0.4)
(0.4)
(0.2)
(0.2)
(0.8)
Data displayed as absolute frequency (percentage).
AV ⫽ atrioventricular; TIA ⫽ transient ischemic attack; other abbreviations as in Table 1.
(0.1)
(1.8)
(0.9)
(0.9)
(1.0)
(0.9)
(0.1)
(1.8)
(0.5)
(0.8)
(0.4)
(0.1)
(0.6)
(0.4)
(0.1)
(0.1)
(5.2)
(0.4)
(1.4)
(1.4)
(0.8)
(0.8)
(2.0)
(0.4)
(1.2)
(0.4)
(0.4)
(1.2)
(0.4)
(0.4)
(0.4)
(6.0)
(1.7)
(0.8)
(0.8)
(0.8)
(0.8)
(0.8)
(0.8)
(3.4)
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Heart Rhythm, Vol 8, No 11, November 2011
Table 3 Univariate predictors of major complications from
catheter ablation (n ⫽ 1,676)
Characteristic
Age
Age ⱖ70 y
Female
Weight (kg)
BMI
BMI categories
⬍25
25–29.9
ⱖ30
LVEF (%)
LVEF ⱕ30%
Medical history
Hypertension
Coronary artery disease
Diabetes mellitus
Prior CVA
Laboratory values
INR
INR ⱖ2.0
Creatinine (mg/dl)
Creatinine ⬎1.5 mg/dl
Procedure types
SVT ablation
AF ablation*
VT ablation with SHD*
VT ablation, idiopathic*
Procedural factors
Access ⱖ4 sheaths
Complication
n ⫽ 64
None
n ⫽ 1,614
60.6 ⫾ 13.9
26.6%
31.3%
86.5 ⫾ 21.6
28.7 ⫾ 6.4
57.5 ⫾ 14.4
18.7%
34.1%
88.1 ⫾ 20.3
28.7 ⫾ 5.9
.44
.11
.64
.75
.79
30.2%
33.3%
36.5%
52.2 ⫾ 15.2
15.1%
27.1%
38.6%
34.3%
53.1 ⫾ 13.8
12.2%
.72
57.8%
5.1%
18.8%
12.5%
47.1%
3.5%
15.3%
5.3%
.09
.14
.45
.02
1.9 ⫾ 0.7
50.0%
1.14 ⫾ 0.6
14.1%
1.7 ⫾ 0.7
33.6%
1.03 ⫾ 0.5
6.1%
.04
.01
.05
.01
6.3%
64.1%
23.4%
6.3%
32.3%
46.1%
14.5%
7.1%
⬍.01
⬍.01
.06
65.6%
48.9%
.01
P
.33
.30
Data shown as mean ⫾ SD or percentage.
Abbreviations as in Table 1.
*Reference ⫽ non-AF SVT ablation.
prompting temporary discontinuation of anticoagulation,
which was followed by a major thromboembolic complication in the setting of a subtherapeutic INR.
Other major complications included aspiration pneumonia
(3), and 1 traumatic urinary catheter event leading to acute
renal failure that eventually resolved. There was 1 case of
conduction system damage necessitating permanent pacing
that occurred during AF ablation when ablation was performed
in the coronary sinus os. There was no case of atrioventricular
block in 524 SVT ablations, of which 169 were AVNRT.
Similarly, there were no significant pulmonary vein stenosis or
atrioesophageal fistulas after AF ablation.
Because of the large component of major complications
occupied by access complications, we also performed subanalysis to evaluate predictors of this particular complication
group. In a multivariate model controlling for the type of
procedure, serum creatinine ⬎1.5 mg/dl was shown to be a
predictor for access complications as well (odds ratio [OR]
4.0, 95% confidence interval [CI] 1.4 to 11.9, P ⫽ .012).
Discussion
Main findings
This study provides an update on the incidence of major
complications of cardiac catheter ablation at a high-volume
center. Our analysis showed that catheter ablation in general is
associated with a low risk, but that complication rates vary by
as much as a 5- to 8-fold between various types of ablation
procedures. Whereas the existence of this difference is not
surprising, the magnitude of the difference is notable and could
be useful when weighing the risks and benefits of different
types of procedures. Among several patient and procedural
characteristics, serum creatinine level of ⬎1.5 mg/dl was associated with major complications in general and more specifically with access complications.
Incidence of major complications by type of
procedure
When comparing our results with previous literature, it seems that
complication rates for SVT ablations have diminished over time.
The Multicenter European Radiofrequency Survey (MERFS)1
reported complication rates for SVT ablations during the years
1987 until 1992 ranging from 3.2% (atrioventricular junction
ablations) to 8.0% (AVNRT ablations), with a 5.1% incidence of
complete heart block in the latter subgroup. For 1992 to 1995,
Calkins et al3 reported for ablations of accessory pathways,
AVNRT, and atrioventricular junction a complication rate of 3%,
and 0.3% periprocedural death. The incidence of complete heart
block had further decreased, being 1.0% at that time. In 1997 a
NAPSE survey2 from 68 centers revealed major complication
rates of 0.6% to 5.0% for various SVT procedures. In our SVT
group, the complication rate was 0.8% without a procedure-reTable 4 Multivariate predictors of major complications from
catheter ablation (n ⫽ 1,626)
Univariate analysis
Characteristic
Odds
ratio
95% CI
P
In univariate analysis, patients with major complications
were roughly twice as likely to have a prior history of a
cerebrovascular accident (CVA), elevated serum creatinine,
and higher INR levels (Table 3). Furthermore, more complex types of ablation procedures were associated with a
higher complication rate.
Age ⱖ70 y
Female gender
BMI ⱖ30
LVEF ⱕ30%
Hypertension
Coronary artery disease
Diabetes mellitus
Prior CVA
INR ⱖ2.0
Creatinine ⬎1.5 mg/dl
AF ablation*
VT ablation, VT with SHD*
VT ablation, idiopathic VT*
Access ⱖ4 sheaths
1.26
1.23
0.98
0.75
1.26
0.97
1.02
2.1
1.73
2.48
5.53
8.61
5.93
1.25
0.70–2.42
0.69–2.18
0.57–1.69
0.29–1.95
0.73–2.15
0.48–1.96
0.51–2.07
0.91–4.68
0.91–3.26
1.07–5.76
1.81–16.83
2.37–31.31
1.40–25.02
0.70–2.24
.49
.48
.94
.55
.40
.93
.95
.08
.09
.03
⬍.01
⬍.01
.02
.44
Multivariate analysis
Multivariate analysis adjusted for all variables from our univariate analysis (Table 4). In this analysis, only procedure type
(SVT as reference) and baseline serum creatinine were independent predictors, whereas age, gender, BMI, INR level,
number of sheaths, and other comorbidities were not predictive.
Abbreviations as in Table 1.
*Reference is non-AF SVT ablation.
Bohnen et al
Complications From Contemporary Catheter Ablation
1665
Thromboembolic events
lated death and without a case of complete heart block, indicating
a further decreased risk. It is worth noting that surveys mentioned
earlier were retrospective, voluntary, and did not include demographics or an adjusted analysis.
Complications from AF ablations were reported in a 1995–
2002 worldwide voluntary survey4 showing a major complication rate of 6.0%, and updated from 2003–2006, reporting a
rate of 4.5%.9 Other single-center studies conducted during the
years from 2005–2008 showed major complications ranging
from 3.9%10 to 5.0%.11 A multicenter Italian study from 2005–
2006 showed a major complication rate of 3.9%.12 In our
cohort, we found a similar major complication rate of 5.2% for
AF ablation procedures. The slightly higher complication rate
at our institution may be explained by different patient populations and a different definition of outcomes to some of the
mentioned studies. As established by Cappato et al,9 the rate of
major complications does not seem to decrease with more
experience.
Scant data exist on idiopathic VT ablation safety.13–15 Most
studies are too small to allow reliable conclusions, or did not
primarily focus on complications. We found a rate of major
complications of 3.4%. Furthermore, there does not seem to be
a significant difference between right heart (3.2%) and left
heart (3.5%) idiopathic VT ablations.
Major complication rates for ablation procedures of VT
with SHD vary widely up to 15%.16 The MERFS study (1987),
which did not distinguish between SHD and idiopathic VT,
showed a rate of 7.5%.1 More recently, multicenter trials of VT
ablation in patients with advanced structural heart disease
found complication rates of 5% to 8%,5,17 with a 3% procedure-related mortality. In our cohort of VT in SHD, the complication rate was relatively low (6.0%) with only 1 (0.4%)
death. It is notable that advanced pump failure therapies such
as ventricular assist devices were available at our institution.
Thus, it seems that the safety of VT ablations has increased
further despite the sick patient population.
Complications related to the site of vascular access are the most
common major complication, but generally do not lead to longterm disability or mortality. AF and VT with SHD procedures had
a higher incidence of femoral access complications than SVT
procedures, presumably related to the different needs for anticoagulation and vascular access. For SVT ablation, the major access
complication rate was 0.4%, consistent with other studies, ranging
from 0 to 0.3%.1,2 Regarding AF ablations, the published literature reports access complications from about 1%20,21 up to 14% of
cases,25 but comparability is impaired by the several different
definitions of outcome used. Our rate of 1.8% was based on the
definition suggested in previously published guidelines,19,23
which still leaves room for interpretation. Patients undergoing a
VT ablation experience an access complication rate of 0.7% to
4.7%.14,24 In our study, the incidence ranged from 0.8% to 2.0%,
being higher for ablations for VT with SHD.
Cardiac perforation
Predictors of major complications
The overall incidence of cardiac perforation was 1.3%, with
the risk being higher in AF (1.8%) and VT with SHD (1.4%)
than in SVT ablations (0.2%). This may be explained by longer
catheter manipulation time, delivery of more lesions, and
greater anticoagulation. The MERFS study1 reported for SVT
ablations a rate of 0.1% to 1.3%, similar to results by Calkins
et al3 of 0.6%. In previous studies assessing the risk of perforation during left atrial ablation, the incidence of perforation
was 2.4%18 and 2.9%.19 The AF survey reported a 1.2%
incidence,4 the updated survey a 1.3% incidence of perforation.9 Regarding ablation for VT with SHD, a multicenter
study reported a 2.7% perforation rate.5 We have previously
published a 1% rate.20 It is thought that atrial perforation is
higher than in the ventricles. However, we could not find a
significantly increased risk in AF versus VT with SHD or
idiopathic VT. Ventricular perforation more frequently led to
tamponade and cardiac surgery. An explanation may be the
higher ventricular systolic pressure, making it less likely for the
bleeding to stop.
In our study, thromboembolic events occurred exclusively in
complex ablation procedures (AF and VT), where left heart
access occurred. Although sporadic thromboembolic events
have been reported for SVT ablations, the incidence is generally very low (approximately 0.5%).1,3 For AF, Oral et al21
found a risk of thromboembolic events of 1.1%. Scherr et al22
and the worldwide AF survey reported a 1.4% and 0.94%9
incidence of CVA. In our series, the thromboembolic event
rates were 1.0% of AF ablations, consistent with previous studies.
For both types of VT ablations, the rate of thromboembolic events
was 0.8%, which is lower than reported in a previous study
(2.7%)5 and estimated in a consensus document (1.3%).7
An important problem often encountered in clinical practice
is the management of patients with bleeding complications
who at the same time are at increased risk for a thromboembolic
event in the periprocedural period. Two of our patients had a
bleeding complication before their major thromboembolic event,
emphasizing the challenge of managing these situations.
Vascular access complications
Identification of impaired renal function as a predictor of adverse events in cardiac procedures, as was the case in our
study, has been demonstrated in previous literature.25–28 This
may result from a higher prevalence of cardiovascular risk
factors in these patients, but also from enhanced atherogenesis
due to factors associated with renal dysfunction itself,29 such as
inflammation and oxidative stress. Additionally, an elevated
serum creatinine level is a validated predictor for adverse
outcomes after general surgery,30 coronary artery bypass
graft,31 and percutaneous coronary intervention.32
Prior studies have investigated risk factors for major
complications from AF ablation procedures. These predictors included advanced age ⬎70 years, female gender, presence of coronary artery disease, and history of congestive
heart failure.10 –12,33 However, studies specifically focusing
on these patient populations failed to show an increased
risk.32–36 Similarly, we did not find an association between
major complications and these or other patient factors. None
of these studies investigated the impact of impaired renal
1666
function on the risk of catheter ablation. Furthermore, the
safety of ablation with therapeutic INR has also been demonstrated in previous literature.24
Study limitations
First, our study represents a single-center experience; however,
procedures were performed by multiple primary operators with
varied backgrounds. Second, the setting of this study was a large
tertiary referral center with possibly more complex and ill patients.
Hopefully, adjustment for confounding factors helps to address
this issue. Another potential limitation is the possibility of missed
complications from patients referred from longer distances. In
these patients, follow-up was often obtained through referring
physician correspondence or telephone follow-up. In total, follow-up was obtained in 96% of the entire cohort, and all patients
were given written instructions to notify the operating physician of
any complications postdischarge. In addition, because major complications are considered and the majority occurred in a short time
span, it is unlikely that a significant number of major complications was missed. Intracardiac ultrasound was used in 86% of
transseptal procedures. This may be a limitation to the extent that
other centers may have different use of this technology. Finally, a
larger cohort may provide a greater statistical power, and may
allow for more clinical variables to be adjusted for in order to
increase the chance of controlling for all possible confounders,
especially when analyzing rare outcomes. It is also possible that
more complex procedures with higher event rates could have a
greater influence on the results.
Conclusion
In the contemporary practice of catheter ablation, major
complications rates vary from 0.8% to 6.0% depending on
procedure type and patient factors. A preprocedural serum
creatinine level of ⬎1.5 mg/dl identifies patients at higher
risk for a major complication and for access complications,
regardless of the type of ablation procedure. Our findings
could be used to weigh the risks and benefits of a planned
procedure. These results may also assist with planning further studies of the safety and outcomes of ablation.
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