Single ring isolation is superior to circumferential pulmonary vein isolation plus modified posterior box isolation with a high power of 40-45 W in patients with persistent atrial fibrillation

doi:10.21203/rs.3.rs-2580364/v1

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Single ring isolation is superior to circumferential pulmonary vein isolation plus modified posterior box isolation with a high power of 40-45 W in patients with persistent atrial fibrillation

https://doi.org/10.21203/rs.3.rs-2580364/v1

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This study aimed to evaluate the superiority of single ring isolation (SRI) over circumferential pulmonary vein isolation (CPVI) plus modified posterior box isolation (MPOBI) using a high power of 40-45 W in patients with persistent atrial fibrillation (PeAF). We retrospectively studied 77 PeAF patients who underwent primary radiofrequency catheter ablation (RFCA). They were divided into the SRI group and the CPVI+MPOBI group according to the RFCA methods. Basic characteristics, procedural variables and AF recurrence rates at 3 months postprocedure were collected and compared between the two groups after propensity score matching (PSM) for age and left atrial diameter. After PSM, 28 patients in the SRI group were matched with 28 individuals in the CPVI+MPOBI group. Compared with the CPVI+MPOBI group, the total procedure time in the SRI group was not significantly shorter ( P =0.928). The total ablation time and ablation time of the PVs and posterior left atrium (ring ablation time) of patients with SRI were significantly shorter than those of patients with CPVI+MPOBI (all P <0.001). The total ablation spots and initial ring spots in the SRI group were significantly fewer than those in the CPVI+MPOBI group (all P <0.001), but the total additional spots were not different between the two groups (P=0.060). The proportion of immediate sinus rhythm was significantly higher in patients with SRI than in those with CPVI+MPOBI (P<0.001). At the follow-up analysis, the AF recurrence rate did not significantly differ between the SRI and CPVI+ MPOBI groups (14.3% vs. 17.9%, P=0.716). In conclusion, this study demonstrated that SRI with a high power was safe and effective for patients with PeAF, and it was superior to CPVI+MPOBI.

Health sciences/Cardiology

Health sciences/Diseases

persistent atrial fibrillation

single ring isolation

modified posterior box isolation

recurrence.

Currently, atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide¹, and AF is associated with pathological atrial myocardial dysfunction and remodelling^{2, 3}. Catheter ablation has been proven to be a more effective and safer method to maintain sinus rhythm for patients with paroxysmal AF or PeAF compared to medical treatment, especially among patients who do not respond to antiarrhythmic drug therapy^4–6.

CPVI is the cornerstone for AF catheter ablation based on the crucial observation of electrical triggers of AF in the pulmonary veins⁷. However, CPVI alone seems insufficient, with lower rates of long-term success for nonparoxysmal AF, and further modification of the atrial substrate may be necessary⁸. Electrical isolation of the posterior wall (PW) is an important aspect of the management of PeAF by electrophysiologists⁹. CPVI + BOX or SRI can be applied for electrical isolation of PW. Posterior box isolation (POBI) not only reduces the critical mass for the maintenance of AF but also decreases the rotors and multiple wavelets in the anterior wall, inferior wall and LA appendage during preAF¹⁰.

Previous reports have revealed that patients can obtain additional benefits from posterior LA box isolation (POBI) over PVI in persistent AF (PeAF) ^{11, 12}. However, a prior study revealed that the efficacy of box isolation is similar to that of circumferential PVI for catheter ablation of AF. Few patients achieved PVI with the box method alone¹³. These results are controversial. In addition, modified POBI, which has been performed for patients with PeAF, has been proven to provide significant left atrial reverse remodelling and has a high clinical success rate¹⁴. Otherwise, the available evidence also suggests that ablation can also cause serious complications, such as cardiac tamponade, stroke, atrio-oesophageal fistula and PV stenosis^15–18.

Single ring isolation (SRI) is carried out based on physiological principles to electrically isolate the posterior left atrium and pulmonary veins. This approach limits the amount of ablation in the posterior left atrium, shortens the ablation time and has the potential to reduce collateral damage to the oesophagus, preventing the formation of atrial oesophageal fistula^{19, 20}. On the other hand, a prior study revealed that the recurrence of atrial fibrillation is common after SRI. Reconnection of the posterior left atrium is not uncommon²¹.

Although high power (HP) creates continuous and transmural lesions, most AF medical centres still tend to use 25–30 W for 30–40 s for safety reasons with a 6-well irrigated-tip ablation catheter²². Radiofrequency ablation with 40–50 W has been demonstrated to be safe and effective in terms of clinical outcomes and lesion markers compared to conventional ablation with low power²³.

To date, the relative efficacy of SRI and CPVI + MPOBI ablation with a power of 40–45 w and a 3.5 mm 56-well irrigated-tip ablation catheter remains unknown. Therefore, the aim of this study was to identify the feasibility and safety of high-power SRI for treating PeAF patients and to assess whether it is superior to CPVI + MPOBI by retrospectively analysing the data at our centre.

Study population

A total of 105 consecutive patients with symptomatic PeAF were retrospectively enrolled in this study. They were admitted to our centre and received first-time RFCA for AF from September 2019 to May 2022 at Wujin People’s Hospital. The exclusion criteria were a secondary procedure (n = 2), other RFCA strategy (n = 15), loss to follow-up at 3 months (n = 5), and lack of essential data (n = 6). Finally, 77 eligible patients were included in the analysis.

Our study was approved by the Ethics Committee of Wujin Hospital Affiliated with Jiangsu University. This study was performed in accordance with the Helsinki Declaration. The study was carried out at August 2022. Written informed consent was unavailable because their data was retrospectively collected from the electronic medical records. The informed consent was then waived for above cause by the Ethics Committee of Wujin Hospital Affiliated with Jiangsu University.

Variables and definitions

Basic characteristics, including sex, age, body mass index (BMI), history of hypertension, diabetes mellitus (DM), coronary artery disease (CAD), ischaemic stroke, left atrium diameter (LAD), left ventricular ejection fraction (LVEF), and CHA2DS2-VASc score, were collected from the electronic medical records for all included patients. Variables of the ablation procedure, including the total procedure time, total ablation time, total procedure spots, initial ring spots, total added spots and severe complications, were collected. Venous blood samples were obtained from all patients in a fasting state on the morning following the admission day. Plasma lipid parameters, including fasting glucose (FG), uric acid (UA), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), were evaluated using standard techniques. BMI was calculated using the following formula: [weight/(Height×Height)] (kg/m²).

Hypertension was defined as a systolic blood pressure (SBP) of ≥ 140 mmHg and/or a diastolic blood pressure (DBP) of ≥ 90 mmHg or with the use of any antihypertensive drug²⁴. DM was defined as FBG ≥ 7.1 mmol/l or 2-h postload glucose ≥ 11.1 mmol/l or current use of antidiabetic medications²⁵.

Cather ablation procedure

Procedures were performed under conscious sedation using intravenous fentanyl for anaesthesia. A decapolar catheter (APT Medical, China) was placed in the coronary sinus. After double transseptal punctures, a deflectable pentaray mapping catheter (D75X4F262, Biosense Webster, US) and a 3.5 mm 56-well open irrigated-tip ablation catheter (Thermocool SF, Biosense Webster, US) were advanced into the left atrium for mapping and ablation via the femoral veins. Three-dimensional electroanatomical geometries of the LA and PVs were reconstructed using the pentaray catheter in conjunction with the Carto 3 mapping system after selective PV angiography. Point-by-point PVI was performed using RF energy and a 3.5 mm 56-well irrigated-tip ablation catheter. Intravenous heparin was administered to maintain an activated clotting time of 300 to 350 seconds. Ablation was performed with an interlesion distance ≤ 5 mm, a power of 40–45 W, temperature of 43°C, flow rate of 15 to 18 mL/min and ablation index (AI) of 350–380 at the posterior wall and 450–500 at the anterior wall. In addition, continuous infusions with heparinized saline were connected to the transseptal sheaths to avoid thrombus or air embolism during the procedures.

CPVI was performed with ipsilateral PV isolation in pairs, with an entrance and exit block as the electrophysiological endpoint²⁶. The MPOBI was performed with linear ablation at the roof line connecting both the superior PVs and with a V-shaped linear ablation at the floor line connecting both inferior PVs¹⁴ (Fig. 1A). The SRI was performed as follows: anterior to right pulmonary veins, roof, left pulmonary vein ridge, and then connecting both the inferior PVs with a V-shaped line¹⁹ (Fig. 1B). After ablation, if sinus rhythm was not achieved, ≤ 3 synchronized, biphasic direct current shocks (100 J and 150 J) were delivered externally to restore the sinus rhythm.

Subsequently, the ablation of typical or atypical atrial flutter (AFL), atrial premature or atrial tachycardia was a part of the substrate modification procedure to improve the outcome. After successful isolation of the PVs, programmed pacing and burst pacing within the isolated areas were performed for all preAF patients. The endpoint of the procedure was the absence of electrical activity and the inability to pace the posterior LA and all PVs in sinus rhythm.

Post-ablation care and follow-up of AF recurrence

After the ablation procedure, intravenous heparin was administered for 1 day to all patients, followed by warfarin or new oral anti-coagulation for at least 3 months. All patients were kept on antiarrhythmic drugs for 1 month after ablation unless contraindications were present. The patients were routinely prescribed proton pump inhibitors for 4 weeks after ablation. The enrolled patients were followed up at 3 months after ablation by the referring cardiologists. All patients received a 24-hour Holter recording to detect the incidence of post-procedural atrial arrhythmia. They were included in the pain score during the ablation procedure using the Visual Analogue Scale/Score. Recurrence of AF was defined as ≥ 30 seconds of atrial fibrillation, AFL or atrial tachycardia after a 90-day recovery period.

Statistical analysis

Statistical analysis was performed with SPSS version 25.0. Continuous variables are expressed as the mean ± SD, and non-normally distributed variables are expressed as the median [inter-quartile range]. Categorical variables are presented as frequencies and percentages. The comparisons of continuous variables were analyzed by Student’s t-test, one-way ANOVA or the non-parametric Mann‒Whitney test, as appropriate. Differences between the two groups were tested using the chi-square test for categorical variables.

Propensity score matching (PSM) was performed to minimize potential confounding variables, including age and LA diameter. One-to-one nearest-neighbour matching was conducted using a match tolerance of 0.02. All P values were two-sided. A P value less than 0.05 was considered statistically significant.

Baseline characteristics between the two groups

As shown in Table 1, the present study included 77 patients [(42 (54.55%) males; 70.73 ± 8.46 years)] with highly symptomatic PeAF. They received radiofrequency catheter ablation for the first time. Coronary artery disease was diagnosed in 14 (18.18%) patients. Ischaemic stoke was diagnosed in 10 (10.39%) participants. Hypertension and diabetes mellitus were documented in 54 (70.13%) and 20 (25.97%) patients, respectively. Their mean LA diameter was 45.29 ± 5.32 mm.

Table 1

Comparison of the patients characteristics between the two groups before and after propensity score matching analysis.
Characteristics	Total (n = 77)	Before matching			After matching
Characteristics	Total (n = 77)	SRI group (n = 37)	CPVI + MPOBI group (n = 40)	P value	SRI group (n = 28)	CPVI + MPOBI group (n = 28)	P value
Age, years	70.73 ± 8.46	67.35 ± 9.82	73.85 ± 5.44	0.001	70.61 ± 4.65	72.79 ± 5.21	0.105
Age group, n (%)				0.067			1.00
< 60	4 (5.19)	4 (10.8)	0 (0.0)		0 (0)	0 (0)
≤60 to < 80	66 (85.71)	31 (83.8)	35 (87.5)		26 (92.9)	26 (92.9)
≥ 80	7 (9.09)	2 (5.4)	5 (12.5)		2 (7.1)	2 (7.1)
male, n (%)	42 (54.55)	20 (54.1)	22 (55.0)	0.934	15(53.6)	19 (67.9)	0.274
BMI, kg/m²	25.46 ± 4.55	25.46 ± 5.34	25.45 ± 3.76	0.737	25.92 ± 5.71	25.82 ± 3.76	0.939
Hypertension, n (%)	54 (70.13)	24 (64.9)	30 (76.7)	0.247	18 (64.3)	22 (78.6)	0.237
DM, n (%)	20 (25.97)	9 (24.3)	11 (27.5)	0.751	7 (25.0)	8(28.6)	0.763
CAD, n (%)	14 (18.18)	5 (13.5)	9 (22.5)	0.307	4 (14.3)	6 (21.4)	0.485
Ischaemic stroke, n (%)	10 (10.39)	3(8.1)	5 (12.5)	0.528	3 (10.7)	3 (10.7)	1.00
LAD, mm	45.29 ± 5.32	43.22 ± 4.92	47.20 ± 4.99	0.001	44.86 ± 4.20	46.29 ± 4.95	0.250
LAD group, n (%)				0.008			0.542
< 40	7 (9.09)	7 (18.9)	0 (0.0)		1(3.6)	0(0)
≤ 40 to < 50	56 (72.73)	26 (70.3)	30 (75.0)		23(82.1)	25(89.3)
≥50	14 (18.18)	4 (10.8)	10 (25.0)		4(14.3)	3(10.7)
LVEF, %	58(53–62)	59(56–62)	56.5(51.5–61.5)	0.196	59(56-62.8)	58(53-62.8)	0.411
CHA2DS2-VASc score	3.65 ± 1.61	3.27 ± 1.63	4.00 ± 1.53	0.046	3	4	0.441
FG, mmol/L	5.18(4.74–6.02)	5.11 (4.63–5.95)	5.31 (4.79–6.11)	0.386	5.20(4.74–6.02)	5.18(4.79–5.87)	0.844
UA, µmol/L	414.45 ± 116.88	405.77 ± 116.92	422.48 ± 117.76	0.534	412.01 ± 121.70	406.21 ± 114.42	0.855
TC, mmol/L	4.01 ± 1.00	4.20 ± 0.96	3.84 ± 1.02	0.121	4.23 ± 0.98	3.75 ± 0.78	0.045
TG, mmol/L	1.29(1.04–1.81)	1.30(1.09–1.88)	1.26(0.98–1.79)	0.603	1.28(1.02–1.81)	1.24(0.87–1.75)	0.712
HDL-C, mmol/L	1.35 ± 0.47	1.39 ± 0.56	1.30 ± 0.33	0.387	1.42 ± 0.56	1.22 ± 0.27	0.110
LDL-C, mmol/L	2.38 ± 0.73	2.52 ± 0.69	2.25 ± 0.76	0.105	2.53 ± 0.70	2.28 ± 0.66	0.173

Before PSM, patients in the SRI group were significantly younger than those in the CPVI + MPOBI group (67.35 ± 9.82 vs. 73.85 ± 5.44 years, P = 0.001). The LAD level was significantly higher in the patients with SRI than in those with CPVI + MPOBI (P = 0.001). The proportions of men, hypertension, DM, CAD, ischaemic stroke and levels of BMI, LVEF, FG, UA, TC, TG, HDL-C or LDL-C were comparable between the groups (all P > 0.05). The CHA2DS2-VASc score was lower in the SRI group than in the CPVI + MPOBI group (P = 0.046).

After PSM for age and LAD, 28 patients in the SRI group were matched with 28 individuals in the CPVI + MPOBI group. After PSM, there was no significant difference in the levels of age or LAD between the two groups (all P > 0.05).

Procedure-related variables between the two groups after PSM

Electroanatomic maps of the LA in posteroanterior and right lateral views for the two ablation methods are shown in Figure a and b, respectively. Posterior left atrium isolation was achieved, and the AF was terminated after the procedure in all patients. During the procedure, the ablation of typical or atypical atrial flutter (AFL) or atrial tachycardia was performed in 16 (57.14%) patients in the SRI group. On the other hand, only 5 (17.86%) patients received ablation of AFL or atrial tachycardia in the CPVI + MPOBI group. The ablation rates of other atrial arrhythmias were significantly higher in the SRI group (P = 0.002).

The differences in procedure-related variables between the two groups were examined and are summarized in Table 2. The total procedure time required was not different between the SRI group and the CPVI + MPOBI group (275.64 ± 60.88 vs. 277.14 ± 63.03 min, P = 0.928). However, the total ablation time and ablation time of the PVs and posterior left atrium (ring-ablation time) in patients with SRI were significantly shorter than those in patients with CPVI + MPOBI (49.12 ± 9.16 vs. 61.32 ± 13.03; 29.32 ± 4.59 vs. 45.98 ± 7.77, all P < 0.001).

Table 2

Procedural characteristics between the SRI and CPVI + MPOBI groups.
Variables	SRI group (n = 28)	CPVI + MPOBI group (n = 28)	P value
Procedure time, min	275.64 ± 60.88	277.14 ± 63.03	0.928
Total ablation time	49.12 ± 9.16	61.32 ± 13.03	< 0.001
Ring ablation time, min	29.32 ± 4.59	45.98 ± 7.77	< 0.001
Total ablation spots	144.46 ± 25.07	180.36 ± 31.83	< 0.001
Initial ring spots	87.96 ± 13.76	136.00 ± 22.43	< 0.001
Additional spots	40.63 ± 23.66	28.19 ± 23.81	0.060
Other atrial arrhythmia	16 (57.14%)	5 (17.86%)	0.002
Immediate sinus rhythm	16 (57.10)	3 (10.70)	< 0.001
Gastrointestinal symptoms, n (%)	4 (14.3)	11 (39.3)	0.035

Of note, the total ablation spots and initial ring spots in the SRI group were significantly fewer than those in the CPVI + MPOBI group (all P < 0.001). Moreover, there was no significant difference in the total additional spots between the two groups (P = 0.060).

In addition, immediate sinus rhythm was achieved in 16 (57.10%) patients who underwent SRI after ablation but in only 5 (10.70%) patients with CPVI + MPOBI (P < 0.001). Correspondingly, ≤ 3 synchronized, biphasic direct current (DC) shocks were used to restore sinus rhythm in 28 patients: 12 (42.90%) in the SRI and 25 (89.30%) in the CPVI + MPOBI group. The proportion of patients needing DC shocks to terminate atrial arrhythmias in patients with SRI was significantly smaller than that with CPVI + MPOBI.

No major procedure-related complications, including death, cardiac perforation, or atrioesophageal fistula, occurred in any of the study patients. Fever occurred in 7 patients: 4 (14.29%) and 3 (10.71%) in the SRI and CPVI + MPOBI groups, respectively. Additionally, gastrointestinal symptoms after the procedure, including chest pain, nausea and vomiting, was observed in 4 (12.5%) and 11 (39.3%) patients in the SRI and CPVI + MPOBI groups, respectively. There was a significant difference (P = 0.035).

AF Recurrence Rates

Patients were followed clinically and with 24-hour Holter for AF recurrence after a 3-month recovery period. There was no significant difference in the average follow-up duration between the two groups [95 (93–104) vs. 100 (95–109) days, p = 0.198]. At the follow-up, 4 AF recurrences (2 had AF, 2 had atrial flutter) were detected in the SRI group. Meanwhile, 5 AF recurrences (2 had AF, 2 had atrial flutter, and 1 had atrial tachycardia) were recorded in the CPVI + MPOBI group. The AF recurrence rate was lower in the individuals with SRI. However, the difference was not statistically significant between the two groups (14.3% vs. 17.9%, P = 0.716). Additionally, the pain score during the procedure was retrospectively investigated when the patients were followed up by the referring cardiologists using the Visual Analogue Scale/Score. Questionnaires revealed that the pain score was significantly lower in the SRI group than in the CPVI + MPOBI group (2.79 ± 0.63 vs. 4.68 ± 1.06, P < 0.001).

In this single-centre, retrospective study, we investigated the difference between SRI and CPVI plus MPOBI with high power in propensity-score-matched patients in terms of efficacy and safety. There were four main findings. First, the ablation time, total ablation spots and initial ring spots in the SRI group were significantly lower than those in the CPVI + MPOBI group. Second, the proportion of patients with immediate sinus rhythm was significantly higher in the SRI group during the ablation procedure. Third, a significant reduction was observed in the procedure-related gastrointestinal symptoms and chest pain score in patients with SRI in comparison to those with CPVI + MPOBI. Fourth, the 3-month AF recurrence rate did not differ significantly between the SRI and CPVI + MPOBI groups.

Prior reports suggested that AF is an important cause of morbidity and mortality worldwide. Cather ablation can certainly reduce the complications and recurrence of AF in clinical practice. To date, to achieve satisfactory outcomes, ablation of the pulmonary veins and posterior atrium is a better strategy for cardiologists based on both laboratory and clinical studies.

Due to its special technique, SRI ablation can reduce the ablation spots and injury to the posterior left atrium. Previous studies have demonstrated that SRI plays an important role in decreasing the ablation time^{19, 20}. Consistently, in the present study, the ablation time of PVs and posterior atrium with SRI was significantly shorter than that of CPVI + MPOBI (P < 0.001). Moreover, the total ablation time was significantly shorter in the SRI group (P < 0.001). There were significant improvements both in total ablation spots and total ring spots during the ablation procedure for patients with SRI (all P < 0.001). Nevertheless, for the total procedure time, our results failed to show a significant difference between the groups. These results are similar to a previous report, in which PVI can be achieved with a similar procedural time²⁷.

Undeniably, there was a significantly higher ablation rate of atrial flutter (AFL) or atrial tachycardia in the SRI group than in the CPVI + MPOBI group, which should be considered when interpreting the outcomes. In addition, it is difficult for inexperienced operators to achieve the isolation of PVs and PW by a single ring. More practice (> 20 cases) may improve the efficiency of SRI and reduce the procedural time. Hence, SRI could be superior in terms of total procedure time for the majority of patients. Subgroup analysis for AF ablation alone or with additional atrial arrhythmia ablation could be useful in future, larger studies.

The high-power short-duration (HPSD) ablation strategy comprises the use of higher RFCA power (≥ 40 W) and a shorter duration (5–15 s) of each RF energy application, and HPSD ablation results in larger lesion diameters and smaller lesion depths compared to conventional (20–35 W, 10–30 s) applications²⁸. High-power ablation was previously associated with better procedural effectiveness than conventional RFCA with low power²⁹. Based on these studies, in our study, the findings demonstrated the effectiveness of SRI with a high power of 40–45 w in restoring sinus rhythm, and it was also superior to CPVI + MPOBI. Our data showed that immediate sinus rhythm was achieved in 16 (57.10%) patients who underwent SRI after ablation but in only 3 (10.70%) patients with CPVI + MPOBI. The acute procedural success for converting sinus rhythm was significantly higher in the SRI group. Meanwhile, the proportion of DC shocks to terminate atrial arrhythmias in patients with SRI was significantly lower than after CPVI + MPOBI (P = 0.039). Obviously, the SRI procedure was more effective and comfortable.

An earlier study showed that the posterior left atrium is important for both the initiation and maintenance of AF³⁰. Lim et al³¹ reported that even wider isolation of the pulmonary veins supporting the entire posterior left atrium resulted in even longer AF-free survival. Although the mechanism for the higher percentage of immediate sinus rhythm in patients with SRI is unclear, our findings demonstrated that SRI used in PeAF can significantly improve clinical outcomes and may reduce AF recurrence compared to CPVI + MPOBI. A possible explanation is that more atrial substrates and ganglionated plexuses (GPs) of the intrinsic cardiac autonomic system for maintenance of AF are included in the large, single ring.

Prior studies suggested that fever (73%), neurological (72%), gastrointestinal (41%), and cardiac (40%) symptoms were the most common adverse events presenting between 0 and 60 days post ablation (median 21 days). Atrioesophageal fistula complicating atrial fibrillation ablation is associated with high mortality³². In our study, radiofrequency energy was applied at each point with a power of 40–45 W around the PV and near the oesophagus. No major procedure-related complications, including death, cardiac perforation, or atrioesophageal fistula, occurred in any of the study patients. In addition, the procedure-related gastrointestinal symptoms after ablation were reduced in the SRI group than in the CPVI + MPOBI group (14.3% vs. 39.3%, P = 0.035). The pain score during the procedure was retrospectively investigated when the patients were followed up by the referring cardiologists using a visual analogue scale and patients in the SRI group had significantly lower pain scores during the procedure than those in the CPVI + MPOBI group (2.79 ± 0.63 vs. 4.68 ± 1.06, P < 0.001). Due to the use of retrospective questionnaires, these results may not be entirely consistent with the pain actually experienced with the ablation was performed. In summary, the above results suggested that it was safe to isolate the pulmonary veins and posterior left atrium with the SRI technique using a high power. Patients with PeAF can benefit from this method, more so than CPVI + MPOBI.

Long-term results after pulmonary vein isolation have demonstrated high rates of recurrent arrhythmia after ablation procedures. Arrhythmia-free survival rates after catheter ablation procedures were 40%, 37%, and 29% after 1, 2, and 5 years, respectively³³. A meta-analysis found that wider isolation techniques had lower recurrence rates than ostial isolation in both paroxysmal and persistent AF patients³⁴. In addition, Lim et al³¹ found superiority for SRI against wide antral pulmonary vein isolation with regard to AF recurrence in patients with symptomatic AF (61% paroxysmal, 39% persistent/longstanding persistent). They showed that AF-free survival at 2 years was better after single ring isolation (74% [95% CI, 65–82%]) than wide antral isolation (61% [51–70%]; P = 0.031). In contrast, in the present study, the results revealed that the rates of AF recurrence were not significantly different between the two groups (8.3% vs. 12.5%, P = 0.637) after catheter ablation at the 3-month follow-up. One of the explanations for this difference is that the proportion of PeAF was significantly different between our study and the study of Lim et al. (100% vs. 39%, p < 0.01). Wide antral pulmonary vein isolation may not be sufficient for PeAF, and other ablation strategies are needed, such as posterior box isolation and substrate and trigger ablation³⁵. The posterior wall of the LA is isolated in SRI, which reduces the critical mass for the maintenance of PeAF and may improve the outcome¹⁰. In addition, the comparison of LA diameter, which can play an important role in the ablation outcome, among groups was absent in the abovementioned study. In our study, the differences between the two groups were balanced using PSM. Furthermore, the patients were followed for a shorter period of time. AF recurrence in our study should be evaluated in long-term follow-up.

Several limitations to this study need to be considered. First, owing to the small sample size, our results could be biased. Second, it was a single-centre, retrospective, observational study, and related data such as a comparison of immediate pain scores during the ablation and fluoroscopy time during the procedure were absent. There were no long-term outcomes. Finally, because AF recurrence was assessed on the basis of the symptoms and 24-hour Holter, occurrences of atrial arrhythmia may be missed. A daily self-pulse check and 72-hour Holter monitor should be used to evaluate AF recurrence in future studies.

In conclusion, this study demonstrated for the first time that the ablation strategy of SRI with a high power could be more efficient and safer for a majority of patients with PeAF than CPVI plus modified POBI. Our data provide a practical method of RFCA for persistent AF, but future long-term investigations with larger samples are necessary to confirm our conclusions.

BMI

body mass index

diabetes mellitus

CAD

coronary artery disease

LAD

left atrium diameter

LVEF

left ventricular ejection fraction

fasting glucose

uric acid

total cholesterol

triglyceride

HDL-C

high-density lipoprotein cholesterol

LDL-C

low-density lipoprotein cholesterol.

Availability of data and materials

All data used to support the findings of this study are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

The study was approved by the ethics committee of Wujin Hospital Affiliated with Jiangsu University, Changzhou, China. The written informed consents were not presented from the included patients because the relevant data were retrospectively obtained from the electronic medical records. The study conforms to the principles outlined in the Declaration of Helsinki. The data used in this study were anonymized before its use.

Consent for publication

Not applicable.

Conflicts of Interest

The authors declare that there is no conflict of interest regarding the publication of this paper.

Funding Statement

The study was supported by the Technology Support Project (social development) of Changzhou , Grant Number:CE20205004.

Authors’ contributions

Yanbin Song was responsible for initial manuscript writing. Yanbin Song, Wenhua Li, Bo Xu and Sheliang Xue collected the data.Yanbin Song, Wenhua Li and Jianqiang Xiao reviewed the paper and were responsible for the final version of the manuscript.

Acknowledgments

We are grateful to our colleagues at the Department of Cardiology, Wujin Hospital Affiliated with Jiangsu University, Changzhou, China.

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Single ring isolation is superior to circumferential pulmonary vein isolation plus modified posterior box isolation with a high power of 40-45 W in patients with persistent atrial fibrillation

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Abstract

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Introduction

Material And Methods

Study population

Variables and definitions

Cather ablation procedure

Post-ablation care and follow-up of AF recurrence

Statistical analysis

Results

Baseline characteristics between the two groups

Procedure-related variables between the two groups after PSM

AF Recurrence Rates

Discussion

Conclusions

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Conflicts of Interest

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