2 Methods
The study was designed as a randomized controlled single-center study.
2.1 Patients
Patients aged >18 years with symptomatic AF refractory to
at least one class I or class III antiarrhythmic drug, and referred for
a first catheter ablation procedure at Changhai Hospital between March
2019 and October 2019 were enrolled. All patients provided written
informed consent. Consecutive 218 patients were randomized to either
BigThumb Group (BT Group) or Traditional Follow-up Group (TF Group) by
means of random number table. The baseline clinical features were noted
for each patient and compared for different follow-up strategies. The
study was conducted in accordance with the Declaration of Helsinki. The
study was approved by the institutional review board of Shanghai
Changhai Hospital, Second Military Medical University.
2.2 Ablation procedures
For all cases, standard femoral venous access was achieved using
Seldinger technique with a 6-French and a 7-French sheath in the left
femoral vein and two 8.5-French Swarz sheaths in the right femoral vein.
Coronary sinus catheter and right ventricle catheter were advanced
through left femoral vein. Transseptal access was achieved with
fluoroscopic guidance. A Tacticath Quartz catheter (St Jude Medical, St.
Paul, MN, USA) was used for radiofrequency catheter ablation in each
procedure. The ablation strategy for each case was left to the
discretion of the primary operator.
2.3 The BigThumb heart monitor
The technologies used to monitor AF are advancing at a rapid pace. Among
them, the BigThumb (Shanghai Yueguang Medical Technologies Inc,
Shanghai, China) heart monitor is a National Medical Products
Administration (NMPA) approved smartphone handheld tool that permits
easy and rapid collection of a “one-lead” ECG (bECG) with two thumbs
of users on the device (Figure 1). In parallel, the bECG will also be
sent to doctors automatically. Users can store and review bECGs on their
cellphones. Artificial intelligence (AI) algorithm was applied in new
version of BigThumb (Supplemental information 1). It may improve the
accuracy of automatic diagnosis. The feasibility of the BigThumb applied
in follow-up of patients after ablation was characterized.
2.4 Follow-Up Strategies
Patients in BT Group were provided with and trained to use a BigThumb
ECG monitor, and were instructed to take at least three bECGs every day
and additional bECGs if symptomatic. The patients should mark symptoms
when bECGs were collected. AF was detected by both an automated AF
detection algorithm and an AI algorithm. Two cardiologists will confirm
the diagnosis separately. While AF recurrence of patients in TF Group
were monitored with Holters 3, 6 and 12 months after ablation and ECGs
if there are symptoms. Monitoring data and patient management strategies
were collected and analyzed. A blanking period was defined as three
months after ablation. Oral anticoagulation was recommended after the
“blanking period” when the
CHA2DS2-VASc score >1.
Subsequent adherence on oral anticoagulation of patients were also
recorded.
2.5 Statistical Analysis
Continuous
variables are expressed as mean ± standard deviation, and categorical
variables are expressed as a number and percentage. Continuous variables
were compared using the two-tailed
Student’s t-test, and categorical
variables were compared using the χ2 test or Fischer’s exact test. In
order to investigate the influence of follow-up strategies on AF
recurrence detection, Kaplan-Meier survival curve and log rank analysis
were performed. For Cox regression, univariable regression was performed
first. Variables with a P-value of <0.2 were included in the
multivariable model. A level of significance was set at <0.05
for all reported P-values, and confidence intervals were calculated at
the 95% level. All statistics were calculated using SPSS (Version 24,
IBM, Armonk, NY, USA).