Methods
All patients undergoing CA for AF at our institution between January
2006 and August 2018 were analyzed including repeated procedures for AF
and/or left-sided atrial tachycardias. All patients signed informed
consent about the procedure. The study was approved by the institutional
review board and conducted according to the Helsinki declaration. The
need for informed consent was waived for the study.
Ablation
procedure
Bilateral femoral veins were punctured either using anatomical landmarks
or under direct ultrasound (US)
guidance (from 2016). In the most common setting, two
Swartz™ SL1 8.5 Fr sheaths were introduced via the
right femoral vein and two short sheaths via the left femoral vein: 7 Fr
for coronary sinus catheter and 11 Fr for intracardiac echocardiography
probe. Between 2006 and 2012, the right jugular / subclavian access was
used for coronary sinus catheter placement. For robotic cases (Sensei,
Hansen Medical, Mountain View, CA, USA), which were performed between
2008 and 2011, 14 Fr sheath was employed to accommodate
Artisan™ electromechanical catheter from the right
femoral vein. No arterial access was used for procedure monitoring. In
the early period, sheaths were removed after activated clotting time
(ACT) level dropped below 250 s and the puncture sites were compressed
for 6 hours. Since 2014, the sheaths were removed at the end of the
procedure and venous hemostasis was achieved by “Z”-stitch. Bed rest
was implemented in all patients till the next morning.
Intracardiac echocardiography was used throughout the whole procedure as
an institutional standard. It was used particularly for guiding the
transseptal puncture, determining accurate antral ablation points,
tagging the course of the esophagus, titration of radiofrequency energy,
and early detection of complications.
CA was performed with a 3.5 mm irrigated-tip catheter
(Navistar® Thermocool or Thermocool
Smarttouch® or Celsius® Thermocool;
Biosense Webster, Diamond Bar, CA, USA). The catheter was navigated with
the use of 3D electroanatomic system (CARTO®; Biosense
Webster or Ensite NavX®; St Jude Medical, St Paul, MN,
USA). Linear point-by-point lesions were placed around the ostia of
pulmonary veins with the endpoint of electrical isolation. In patients
with the advanced atrial disease (38%), empirical linear lesions and/or
superior vena cava isolation and/or biatrial electrogram-guided ablation
was performed. Cavotricuspid isthmus was ablated in 22% of procedures.
Mappable ATs were always targeted. Non-inducibility of arrhythmia was
the desired endpoint of repeated procedures.
Radiofrequency energy was delivered by an EP Shuttle™(Stockert, Freiburg, Germany) or Smartablate™(Biosense Webster) or Ampere™ generator (St Jude
Medical). Constant irrigation flow of 15 ml/min (30 ml/min inside the
coronary sinus) through a Cool Flow® pump (Biosense
Webster) or Cool Point™ (St Jude Medical),
respectively, was employed. The power mode was used with a preset power
up to 25–35 W and down-regulation when the tip temperature of 43°C was
achieved. Power output was mostly reduced to 20–25 W at the left atrium
posterior wall and inside the coronary sinus. The energy was delivered
either in point-by-point fashion (20–30 s at one spot) or by dragging.
Rarely (< 5%) other ablation catheters were used; of them
predominantly PVAC™ or Arctic Front®(Medtronic, Minneapolis, MN, USA).
Perioperative anticoagulation
In the early period from 2006 to 2012, warfarin was temporarily
discontinued to achieve International Normalized Ratio (INR) <
2 and bridged with weight-adjusted low molecular weight heparin (LMWH).
At the beginning of every procedure, unfractionated heparin was
administered with a loading dose of 5000 IU before the first transseptal
puncture. The ACT was measured every 15–30 minutes, with the target
value of 300–350 s in all patients during the procedure. After the
procedure, the infusion of unfractionated heparin was administered until
the morning of the first post-ablation day. Subsequently, the warfarin
was restarted and LMWH administered until reaching the therapeutic level
of INR.
From 2013, all procedures were performed on uninterrupted warfarin with
target INR between 2 and 3 or minimally (single dose) interrupted direct
oral anticoagulants. After the procedure, either direct oral
anticoagulants or warfarin were re-started after the drop of the ACT
under 170 s.
Anticoagulation treatment continued for at least 3 months after the
procedure in low-risk patients or lifelong in high-risk patients
according to the guidelines.5
Assessment of complications
The specific institutional tracking system was used to identify all
complications during and after the procedure until the 3-month clinical
outpatient visit. This included a purpose-established central registry
for complications of invasive procedures, which was described
elsewhere.6 All recorded complications were
individually reviewed by staff physicians of the arrhythmia service in
morbidity and mortality meetings and classified as vascular or other,
and major or minor.
Definition of complications
Major complications were defined as those that result in permanent
injury or death, require intervention for treatment, prolong
(> 48 h) hospitalization or require new
hospitalization.6 MVCs were major complications
limited to vascular access. Hemoglobin drop by > 30 g/l was
classified as MVC even if it was not treated with blood transfusion.
Statistical analysis
Continuous variables were expressed as means ± standard deviation and
compared by t-test or Mann-Whitney U test, as appropriate. Categorical
variables are expressed as percentages and compared by the chi-square
test, Fisher exact test or logistic regression if appropriate.
Association of baseline clinical and procedural factors with MVCs was
investigated by linear regression analysis. Statistically significant
factors on univariate analysis (P < 0.1) were entered into a
multivariate regression model. Two-tailed α < 0.05 was
considered statistically significant, except for the test of equality of
covariance matrices where P < 0.005 was considered
significant. For post hoc comparison of subgroups, Tukey HSD or
Bonferroni test was used where appropriate. The majority of analyses
were performed separately for males and females. All analyses were
performed using TIBCO Statistica™ version 13.3 (Palo
Alto, CA, USA) or IBM SPSS for MAC version 23 (IBM, New York, USA).