Method
A total of 17,496 patients who underwent catheter ablation of AF for the
first time in Beijing Anzhen Hospital from January 2015 to December 2021
were screened. The inclusion criteria were (1) aged 18 years or older;
(2) diagnosed with AF; (3) history of mitral valve replacement. The
exclusion criteria were a history of catheter ablation, surgical maze
procedure, left atrial appendage closure or resection. A total of 68
patients who met the inclusion and exclusion criteria were enrolled in
the study. According to the type of MVR, the patients were divided into
two groups: the bioprosthetic MVR group and the mechanical MVR group.
Totally, 12 patients were enrolled in the bioprosthetic MVR group and 56
patients in the mechanical MVR group. Written inform consents were
obtained in all the patients prior to the ablation procedure. The study
was approved by the institute ethics committee.
Catheter ablation of AF
All anti-arrhythmic drugs except amiodarone were discontinued for at
least 5 half-lives before catheter ablation. The procedure was performed
under fasting, conscious sedation and uninterrupted anticoagulation.
During the procedure, heparin was injected intravenously to maintain the
activated clotting time at 300-400s. AF ablation strategy was described
previously9. The left atrium geometry was
reconstructed in the CARTO system, with a 3.5 mm tip ablation catheter
point by point (Navi-Star Thermocool, or Thermocool-Smart-touch Biosenes
Webster, USA) (2015-2018) or PentRay Nav eco tip catheter (Biosenes
Webster, USA) with fast anatomy mapping (Since 2018). The patients with
paroxysmal AF were treated with circumferential pulmonary vein ablation
(CPVA), the ablation endpoint is all pulmonary veins isolation (PVI).
After CPVA in patients with persistent AF, LA roofline, mitral isthmus
(MI), and cavotricuspid isthmus (CTI) was routinely targeted. If AF was
still persistent, 200 J direct current cardioversion was performed to
convert AF to sinus rhythm. Additional ablation was applied, if needed,
to achieve PVI and linear block in sinus rhythm. Coronary sinus (CS),
superior vena cava (SVC), fractionated potentials (CFAEs), and ligament
of Marshall (LOM) were targeted at the physician’s discretion.
Data collection and follow-up
Antiarrhythmic drugs were routinely taken orally for 3 months after the
procedure. The patients in the bioprosthetic MVR group were given new
oral anticoagulants. The patients in the mechanical MVR group were given
warfarin, targeting the international normalized ratio range of
2.0–3.0. 24h-Holter was performed monthly in the first 3 months, which
was followed by 24h-Holter 6 months after the procedure and every 6
months thenceforth. Scheduled follow-up was implemented by telephone
interview or outpatient follow-up to collect the occurrence of endpoint
events at 3, 6, months and every 6 months thereafter. The follow-up
information was collected by professionally trained follow-up personnel.
If the patient had palpitations or other symptoms suggestive of
arrhythmia, ECG examination was performed in the local hospital at any
time.
The study endpoint was AF recurrence which was defined as any recurrence
of atrial arrhythmias with a duration of ≥ 30 seconds. AF recurrence
occurring within 3 months after the procedure was defined as early
recurrence, and recurrence after 3 months of procedure was defined as
late recurrence. If a patient underwent AF ablation again during the
follow-up, the patient would not be counted in the survival analysis
after the redo procedure.
Statistical analysis
SPSS 26.0 software was used for statistical analysis. All continuous
variables with normal distribution were presented as mean ± standard
deviation, and Independent-Samples t -test was used for
comparison. Medians and quartiles were used for continuous variables
with non-normal distribution, and non-parametric Mann-WhitneyU -test was used for comparison. Categorical variables were
presented as numbers and proportions and compared by
χ2 or Fisher’s exact test. Kaplan-Meier analysis with
log-rank test was used to calculate AF recurrence-free survival between
the groups. COX univariate and multivariate regression analyses were
used to assess independent predictors of AF recurrence after the
catheter ablation. A p -value < 0.05 was considered
statistically significant.