Prognostic Value of High-sensitive Troponin T for Predicting Cardiovascular Events After Atrial Fibrillation Ablation

Shota Tamura MD; Atsushi Doi MD, PhD; Masanori Matsuo MD; Hisashi Katayama MD; Tomotaka Yoshiyama MD; Hiroaki Tatsumi MD, PhD; Yasuhiro Izumiya MD, PhD; Minoru Yoshiyama MD, PhD


J Cardiovasc Electrophysiol. 2019;30(9):1475-1482. 

In This Article


Patient Population

A total of 227 consecutive patients with AF (mean age, 66 ± 10 years; persistent AF, n = 98), defined according to the 2014 American Heart Association/American College of Cardiology/Heart Rhythm Society guidelines, treated with contact force radiofrequency catheter ablation (CF-RFCA) (n = 177) or cryoballoon ablation (CBA) with a second-generation catheter (n = 50) for the first time between June 2014 and October 2017 were enrolled in this study. All patients had symptomatic AF refractory to at least one antiarrhythmic drug. The exclusion criteria were as follows: (a) age, less than 20 or greater than equal to 85 years, (b) presence of an intracavitary thrombus, (c) uncontrolled heart failure, (d) moderate or severe valvular heart diseases, and (e) significant coronary artery stenosis with greater than or equal to 50% luminal narrowing on a multidetector computed tomography scan. Patients were enrolled after the application of these exclusion criteria. All patients provided their documented informed consent, and the institutional ethical review committee approved our study.

High-sensitive Troponin T Analysis

Plasma samples were obtained from all patients before the ablation and frozen in aliquots and stored at −70°C until analyzed. The hs-TnT levels were determined with sandwich immunoassays using a Cobas Analysis 3601 immunoanalyzer or a highly sensitive quantitative electrochemiluminescence immunoassay (Elecsys 2010; Roche Diagnostics, Mannheim, Germany). We divided all patients into 3 groups according to the hs-TnT level. The value of hs-TnT levels at the 99th percentile in healthy populations was reported to be 0.014 μg/L.[12] Therefore, we defined the cutoff point for high hs-TnT levels as greater than or equal to 0.014 μg/L. There were 46 patients in the high hs-TnT group (greater than or equal to 0.014 μg/L: the 80th percentile of hs-TnT), and the others were divided into the low (lesser than equal to 0.005 μg/L [n = 54]: the 20th percentile of hs-TnT) and medium hs-TnT groups (0.006-0.013 μg/L [n = 127]).

Ablation Procedure

All patients received oral anticoagulation therapy with warfarin (n = 32) or direct oral anticoagulants (DOACs) (n = 195). Warfarin was continued throughout the procedure, whereas DOACs were discontinued after oral administration 24 hours before the procedure and restarted 6 hours after the procedure at the same dose. The transseptal procedure was guided by intracardiac echocardiography. After inputting introducer sheaths, a single bolus of 5000 U heparin was administered, and continuous heparin infusion was started at 1000 U/hour. The bolus of heparin was adjusted to maintain the activated clotting time at 300 to 350 seconds. The choice between CF-RFCA and CBA was based on the operator's preference. Pulmonary vein isolation (PVI) was performed in all patients. Radiofrequency ablation for nonpulmonary vein foci, complex fractionated atrial electrogram ablation, or both were performed after PVI, if necessary.

Contact Force Radiofrequency Catheter Ablation

Ablation was performed using a 3.5-mm tip-irrigated catheter with a contact force (CF) sensor (Navistar Thermocool Smart Touch; Biosense Webster Inc, Diamond Bar, CA) targeting a maximum temperature of 43°C and maximum power of 25 to 30 W with the guidance of an electroanatomical mapping system (CARTO 3, Biosense Webster Inc). The aim was to achieve a CF of at least 10 g (mean) with a vector perpendicular to the tissue. The defined upper limit of CF was 50 g.

Cryoballoon Ablation

A 28-mm Arctic Front Advance cryoablation catheter was inserted into the left atrium over a spiral mapping catheter (Achieve; Medtronic Inc, Minneapolis, MN). Complete pulmonary vein antrum occlusion was assessed with venous angiography. The freeze cycle duration was 180 seconds. PVI was assessed continuously using the circular Achieve catheter during CBA and by using another circular catheter (Lasso, Biosense Webster Inc) after CBA. If the pulmonary vein remained connected, additional applications were performed using different angulations. If PVI could not be achieved with CBA alone, a radiofrequency ablation catheter was utilized.

Echocardiographic Measurement Parameters

Transthoracic echocardiography (iE33; Philips Medical Systems, Andover, MA) was performed before the ablation. We measured the left atrial anteroposterior diameter (LAD) at the mitral annulus and calculated the left ventricular ejection fraction (LVEF) using a modified Simpson's method. Early transmitral flow velocity (E) and mitral annular velocity on tissue Doppler imaging (e′) were measured, and the E/e′ ratio was calculated.

Patient Follow-up and Clinical Outcome Assessment

After the first procedure, all patients underwent follow-up evaluations (every 1-3 months) at our outpatient clinic. AF recurrence within 3 months after the procedure was considered transient, and a 3-month period was applied as a blanking period. AF recurrence was defined as sustained AF lasting greater than or equal to 30 seconds after the initial procedure. Follow-up examinations including 12-lead electrocardiography, 24-hour Holter monitoring, and assessment of the current condition were performed. All patients who had symptoms without a documented AF recurrence were given an event recorder to identify the cause of their symptoms. When AF recurred during the early unstable period after the procedure, antiarrhythmic drugs that had been previously ineffective were resumed temporarily, and the antiarrhythmic drugs were discontinued if sinus rhythm could be maintained. Repeat ablation was performed in patients with AF recurrence. The assessed clinical outcomes were AF recurrence and MACE (including death, stroke, acute coronary syndrome, and heart failure hospitalization) after the ablation. The composite endpoint was defined as AF recurrence or MACE after AF ablation.

Statistical Analysis

All analyses were performed using JMP version 14 (SAS Institute, Cary, NC). All data are presented as mean ± standard deviation and as number (percentage) for categorical data. Differences between groups were assessed using the Mann-Whitney U and Kruskal-Wallis tests, and categorical data and percentage frequencies were analyzed using the χ 2 test. A Kaplan-Meier analysis with a log-rank test was used to determine the probability of freedom from AF recurrence and the composite endpoint. Univariate and multivariate analyses with Cox proportional hazard models were performed to identify the predictors of the composite endpoint after the initial ablation. For all comparisons, a P < .05 was considered significant.