Patient selection. The institutional review board at the Beijing Anzhen Hospital, Capital Medical University has approved the study. All patients referred for catheter or surgical ablation for LSPAF with moderate-severe TR between January 2008 and December 2013 were considered eligible for inclusion. Patients underwent surgical ablation concomitant with TV repair were included in the surgical cohort. The catheter cohort included patients who underwent ‘2C3L’ ablation. The exclusion criteria were: 1) previous percutaneous coronary intervention or cardiac surgery; 2) patients with more than moderate mitral regurgitation; 3) patients with an ejection fraction of < 40%.
Catheter ablation and surgical procedure. A fixed approach for ablation of long-standing persistent AF was developed, which consists of bilateral circumferential PVAI (‘2C’) and three linear ablation sets (‘3L’) (Fig. 1). Linear ablation is empirically applied across the mitral isthmus (MI), the left atrial (LA) roof, and the cavo-tricuspid isthmus (CTI). Cardioversion was performed if AF persisted or converted into an organized atrial tachyarrhythmia (OAT) following the initial pulmonary vein (PV) antrum and linear ablations. If cardioversion failed or atrial fibrillation (AF) has immediately relapsed, amiodarone was intravenously administered before repeat cardioversion. After the restoration of sinus rhythm (SR), radiofrequency applications were applied, and if needed, to close the gaps along with the circumferential lesions to achieve pulmonary vein antrum isolation(PVAI)was later verified by a circular mapping catheter. Similarly, conduction across the LA roofline, the MI line, and the CTI line were evaluated by using differential pacing manoeuvers. Also if necessary, the ridge between the LA appendage (LAA) and the left superior PV was targeted. Further ablations were conducted to achieve complete linear block as previously reported. If an OAT occurred after PVAI and documented the blockage of the lines, this tachycardia was then ablated with guidance of 3D electroanatomic mapping and conventional electrophysiological manoeuvres. If AF relapsed after PVAI and linear block across the LA roof, MI and CTI lines were achieved, then the superior vena cava (SVC) was isolated following cardioversion. Procedural endpoint included the isolation of PV antrum and complete conduction of block across the three ablation lines.
Patients who experienced arrhythmia recurrence after the blanking period were treated with cardioversion, medication, or repeated ablation at the patient’s and physician’s discretion. A redo procedure followed the ‘2C3L’ strategy where the conduction gaps were targeted, and clinical OATs were also mapped and ablated; however, complex fractionated atrial electrograms (CFAEs) ablation were not performed during the repeat procedure. After completing the PVAI and blockage across the three lines (LA roof, MI, and CTI), burst pacing at 200 ms was applied from proximal coronary sinus (CS) to induce tachycardia. Only the traceable OAT further underwent ablation, and the endpoint included was that the targeting OAT became non-inducible. Otherwise, the procedure was terminated by cardioversion.
Surgical ablation procedure.
Ablation was carried out with bipolar Cardioablate (Medtronic, Minneapolis, MN) or an Atricure clamp (Atricure, West Chester, OH) as we described previously.12 After cross-clamping the aorta, the heart was arrested, and the LA was accessed through left atriotomy. The LA ablation line includes isolation of PVs and a connecting line was performed between both islands of PVs on the roof and a line from the left PVs to the posterior mitral annulus. The LAA was excised or excluded. Right atrial (RA) ablation line includes SVC to inferior vena cava; the lateral free-wall lesion completes the anterior-medial tricuspid valve annulus; medial free-wall lesion completes the anterior-medial TV annulus and CTI ablation. The procedure was considered complete with the ablation of the right appendage.
Tricuspid valve repair. TV annuloplasty was subsequently performed with a Carpentier-Edwards MC3 ring (Edwards Lifesciences). The tricuspid ring was sized according to the combined surface area of the posterior and anterior tricuspid leaflets that are extended using a right-angle hook and implanted with simple, interrupted mattress sutures by sparing the septal annulus and conduction tissue in the region of the apex of the triangle of Koch.
Post-procedure management.
Warfarin was given to maintain the international normalized ratio between 2.0 and 2.5 for the first 3 months to all patients. Patients who have no AF recurrence and a CHADS2 score < 2 stopped taking warfarin 3 months following the procedure. Unless contraindicated, patients received amiodarone or sotalol within 24 hours of the procedure, which were discontinued at three months (blanking period).
Echocardiography.
Comprehensive 2-dimensional (2D) echocardiography was performed with a commercially available system (IE33; Philips Medical Systems, Andover, MA). Standard 2D and Doppler echocardiographic images were acquired in the left lateral decubitus position using a phased-array transducer in the parasternal and apical views by experienced cardiac sonographers. Three consecutive cardiac cycles were recorded and stored for subsequent analysis. Left ventricle end-diastolic (LVEDD) and end-systolic dimensions (LVESD) were measured from parasternal acquisitions. Left ventricle volumes and left ventricle ejection fraction (LVEF) were calculated using Simpson’s biplane method according to the guidelines of the American Society of Echocardiography.13 LA and RA areas were measured by planimetry at end-systole from the apical 4-chamber views. Left atrial volumes were measured by Simpson’s biplane method. Color flow was applied in the apical 4-chamber view to assess the severity of TR, which was then graded semiquantitatively based on a scale of 0 to 4, where 0, none or trace; 1+, jet area/atrial area < 10% (mild TR); 2+, jet area/atrial area 10–20% (moderate TR); 3+, jet area/atrial area 20–33% (moderate-severe TR); and 4+, jet area/atrial area > 33% (severe TR).14 Tethering height was measured by tracing between the atrial surface of the leaflets and the tricuspid annular plane at the time of maximal systolic closure. From the apical 4-chamber view, the RV end-systolic and end-diastolic areas were measured by planimetry by positioning the transducer to maximize the RV area and to include the RV apex. RV fractional area change (RVFAC) was used to determine the RV systolic function and was calculated by the following formula: FAC=([diastolic area systolic area]/diastolic area) × 100%.15 RV long-axis length and RV short-axis width at the midventricular level were measured as described by Matsunaga and Duran and used to calculate the end-diastolic RV sphericity index (RVSI) as previously described (RVSI = RV long-axis length/RV short-axis width).16 Systolic pulmonary artery pressure (sPAP) was measured by echocardiography using the modified Bernoulli equation on the transtricuspid continuous-wave Doppler signal, while adding pressure on RA. The TV tethering height and TV tethering area were measured by tracing between the atrial surface of the leaflets and the tricuspid annular plane at the end-systole.
Patient follow-up. All patients had visits scheduled at 1, 3, and 12 months postoperatively and every 1 year thereafter. At each visit, the patient’s history, physical examination, chest X-ray, a 24-hour Holter, and echocardiogram were performed and obtained. The earliest echocardiogram on which moderate or greater TR was indicated for each patient was used to designate recurrent TR.
Statistics
All continuous variables are presented as mean standard deviation (SD), categorical values are presented as percentages, and odds ratios are presented with 95% confidence intervals (CIs). Comparisons between surgical and catheter cohorts were done by t test for continuous variables, chi-square test for categorical variables. A univariate and multivariate Cox hazard regression analysis was used to identify predictors of survival and freedom from events. The optimal cut-off value of the parameters in predicting the recurrence was identified using receiver operating characteristic (ROC) curve analysis. The area under the ROC curve (AUC) was calculated and compared by the DeLong method. Variables selected to be tested on multivariate analysis included those with P < 0.1 on univariate analysis. To reduce the effect of potential confounding factors in subgroup analysis, propensity-score match (PSM) analysis was used. The analysis was performed by matching patients in the 2 groups at a 1:1 ratio, without replacement, by the nearest neighbor technique, using a caliper width equal to 0.2 of the SD of the logit of the propensity score. A competing risk regression model was used to assess AF recurrence and stroke with death as a competing event. All significance tests were 2-tailed, and p value of < 0.05 was considered to be statistically significant. All analyses were performed with Stata/SE version 15 (Stata Corporation, Lakeway Drive College Station, TX, USA).