The relationship between right atrial wall inflammation and poor prognosis of atrial fibrillation based on 18F-FDG positron emission tomography/computed tomography.

Background: Atrial fibrillation (AF) has been identified to increase stroke risk, even after oral anticoagulants (OACs), and the recurrence rate is high after radiofrequency catheter ablation (RFCA). Inflammation is an essential factor in the occurrence and persistence of AF. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is an established molecular imaging modality to detect local inflammation. We aimed to investigate the relationship between atrial inflammatory activity and poor prognosis of AF based on 18F-FDG PET/CT. Methods: A total of 204 AF patients including 75 with paroxysmal AF (ParAF) and 129 with persistent AF (PerAF) who underwent PET/CT before treatment were enrolled in this prospective cohort study. Clinical data, electrocardiograph (ECG), echocardiography, and cardiac 18F-FDG uptake were collected. Follow-up information was obtained from patient clinical case notes or telephone reviews, with the starting point being the time of PET/CT scan. The follow-up deadline was either the date of AF recurrence after RFCA, new-onset stroke, or May 2023. Cox proportional hazards regression models were used to identify predictors of poor prognosis and hazard ratios (HRs) with 95% confidence intervals (CIs) was calculated. Results: Median follow-up time was 29 months [interquartile range (IQR), 22-36 months]. Poor prognosis occurred in 52 patients (25.5%), including 34 new-onset stroke patients and 18 recrudescence after RFCA. The poor prognosis group had higher congestive heart failure, hypertension, age ≥75 years (doubled), diabetes mellitus, prior stroke or transient ischemic attack (TIA) or thromboembolism (doubled), vascular disease, age 65-74 years, sex category (female) (CHA2DS2-VASc) score [3.0 (IQR, 1.0-3.75) vs. 2.0 (IQR, 1.0-3.0), P=0.01], right atrial (RA) wall maximum standardized uptake value (SUVmax) (4.13±1.82 vs. 3.74±1.58, P=0.04), higher percentage of PerAF [39 (75.0%) vs. 90 (59.2%), P=0.04], left atrial (LA) enlargement [45 (86.5%) vs. 104 (68.4%), P=0.01], and RA wall positive FDG uptake [40 (76.9%) vs. 79 (52.0%), P=0.002] compared with the non-poor prognosis group. Univariate and multivariate Cox proportional hazard regression analysis concluded that only CHA2DS2-VASc score (HR, 1.29; 95% CI: 1.06-1.57; P=0.01) and RA wall positive FDG uptake (HR, 2.68; 95% CI: 1.10-6.50; P=0.03) were significantly associated with poor prognosis. Conclusions: RA wall FDG positive uptake based on PET/CT is tightly related to AF recurrence after RFCA or new-onset stroke after antiarrhythmic and anticoagulation treatment.

Scar-related atrial macroreentries: Different arrhymogenic basis generates different reentry type.

BACKGROUND: Catheter ablation is an established therapeutic strategy to treat scar-related macroreentry atrial tachycardia (MAT). However, the scar properties and arrhythmogenicity and the reentry type have not been clearly defined. METHODS AND RESULTS: A total of 122 patients with scar-related MAT were enrolled in this study. The atrial scars were classified into two categories: spontaneous scars (Group A: n = 28) and iatrogenic scars (Group B: n = 94). According to the relationship between scar location and the reentry circuit, MAT was described as scar pro-flutter MAT, scar-dependent MAT, and scar-mediated MAT. The reentry type of MAT was significantly different between Groups A and B: pro-flutter (40.5% vs. 62.0%, p = 0.02), scar-dependent AT (40.5% vs. 13.0%, p < 0.001), and scar-mediated AT (19.0% vs. 25.0%, p = 0.42). After a median follow-up of 25 months, 21 patients with AT recurrence were observed. Compared with the spontaneous group, there was a lower recurrence rate of MAT in the iatrogenic group (28.6% vs. 10.6%, p = 0.03). CONCLUSION: Scar-related MAT has three reentry types, and the proportion of each type varies with the scar properties and its arrhythmogenic basis. Optimization of the ablation strategy based on the scar properties to improve the long-term outcome of catheter ablation of MAT is necessary.

Causal effects of plasma lipids on the risk of atrial fibrillation: A multivariable mendelian randomization study.

BACKGROUND AND AIMS: Observational studies have suggested that plasma lipids contribute substantially to cardiovascular disease, but "cholesterol paradox" in atrial fibrillation (AF) remains. We sought to investigate the causal effects of lipid profiles on the risk of AF. METHODS AND RESULTS: Two-sample Mendelian randomization (MR) framework was implemented to examine the causality of association. Summary estimations of genetic variants associated with low density lipoprotein (LDL)-cholesterol, high density lipoprotein (HDL)-cholesterol, total cholesterol, triglycerides, lipoprotein-a [Lp(a)], apolipoprotein A1 (ApoA 1), and apolipoprotein B (ApoB) were 81, 99, 96, 61, 30, 10, and 23 single nucleotide polymorphisms, respectively. Genetic association with AF were retrieved from a genome-wide association study that included 1,030,836 individuals. The complications for AF were predefined as cardioembolic stroke (CES) and heart failure (HF). In the multivariable MR, the odds ratios for AF per standard deviation (SD) increase were 1.030 (95% confidence interval (CI) 0.979-1.083; P = 0.257) for LDL-cholesterol, 0.986 (95% CI 0.931-1.044; P = 0.622) for HDL-cholesterol, 0.965 (95% CI 0.896-1.041; P = 0.359) for triglycerides, 1.001 (95% CI 1.000-1.003; P = 0.023) for Lp(a), 1.017 (95% CI 0.966-1.070; P = 0.518) for ApoA1, and 1.002 (95% CI 0.963-1.043; P = 0.923) for ApoB. There was no evidence that other lipid components were causally associated with AF, CES, or HF, other than for a marginal association between triglycerides and HF. CONCLUSIONS: This MR study provides robust evidence that high Lp(a) increases the risk of AF, suggesting that interventions targeting Lp(a) may contribute to the primary prevention of AF.

Efficacy of sole pulmonary vein isolation in patients with nonparoxysmal atrial fibrillation without significant left atrium scar.

BACKGROUND: Catheter ablation strategies for nonparoxysmal atrial fibrillation (NPAF) are in varied forms. The mechanisms that circumferential pulmonary vein isolation (CPVI) alone could achieve success in some of the patients with NPAF are not well studied. This study sought to assess the clinical outcome of only CPVI approach in NPAF patients without significant left atrium scar. METHODS AND RESULTS: A total of 241 consecutive patients with NPAF undergoing an initial ablation procedure were studied. After CPVI, cavotricuspid isthmus ablation and direct current cardioversion, high-density atrial voltage mapping was performed during sinus rhythm. Transitional-voltage zone (TZ) was defined as 0.4-1.3 mV, and low-voltage zone (LVZ) as <0.4 mV. No LVZs were identified in 101 patients (41.9%), and only CPVI was performed. Among the patients without LVZs, single-procedure freedom from atrial fibrillation (AF)/atrial tachycardia was achieved in 73 patients (72%), while 28 patients (28%) had AF recurrence with mean follow-up of 29 ± 14 months. TZ index (TZi) was deduced by calculating the ratio of all TZ points over the total number of points and was found to be a univariate predictor of recurrence after a single procedure (P  =  0.047). CONCLUSIONS: The CPVI alone strategy for patients with NPAF can be performed in highly selective patients without LVZs. TZi may reflect healthy extent of left atrium, which has trend toward the association with AF recurrence.

Localized reentry as a novel type of the proarrhythmic effects of linear ablation in the left atrium.

BACKGROUND: There is a consistent understanding that the proarrhythmic effect of linear ablation in the left atrium body for atrial fibrillation (AF) always manifests as the macroreentry tachycardia. However, its genesis of localized reentry has been underestimated. METHODS: Among 90 persistent AF patients who had accepted linear ablation in the left atrium body, a total of 11 patients (12%) presented with a localized reentry (six men, mean age 59 ± 11 years) associated with previous ablation lines. Among the 11 patients, four were encountered during the index procedure for AF ablation and the remaining seven during the redo procedure for atrial tachycardias (ATs). RESULTS: The ATs were all located at previously ablated lesion sites and manifested a centrifugal mode in both the activation mapping and pattern of the postpacing interval response. The mean tachycardia cycle length (TCL) of the localized reentrant ATs was 306 ± 73 ms. The target sites demonstrated low amplitude (0.17 ± 0.09 mV) continuous complex electrograms or long double potentials, covering 142 ± 57 ms (46 ± 12 % of the TCL). The localized reentrant tachycardias were all successfully eliminated by catheter ablation. CONCLUSIONS: A novel type of the proarrhythmic effects of linear ablation in the left atrium for AF may manifest as localized reentrant ATs, as evidenced by the association of the site of origin with the prior lesions.

Noncavotricuspid isthmus-dependent right atrial tachycardia after paroxysmal atrial fibrillation ablation.

BACKGROUND: Atrial tachycardia (AT) is commonly encountered after atrial fibrillation (AF) ablation. But no study exclusively on noncavotricuspid isthmus-dependent right AT (NCTI-RAT) post-AF ablation has been reported. The present study aims to describe its prevalence, electrophysiological mechanisms, and ablation strategy and to further discuss its relationship with AF. METHODS: From July 2006 to November 2009, 350 consecutive patients underwent catheter ablation for paroxysmal AF. A total of seven patients (2.0%) developed NCTI-RAT after left atrium ablation for AF. In these highly selected patients (two male, mean age 54 ± 11 years, mean left atrium diameter of 34 ± 7 cm), all had circumferential pulmonary vein isolation in their initial procedures and three of them had additional complex fractionated electrograms ablation in the left atrium and the coronary sinus. RESULTS: Totally, nine NCTI-RATs were mapped and successfully ablated in the right atrium with a mean cycle length of 273 ± 64 ms in seven patients. Five ATs in three patients were electrophysiologically proved to be macroreentry and the remaining four were focal activation. All the ATs were successfully abolished by catheter ablation. After a mean follow-up of 29 ± 15 months post-AT ablation, all patients were free of AT and AF off antiarrhythmic drugs. CONCLUSIONS: NCTI-RAT is relatively less common post-AF ablation. Totally, 2.0% of paroxysmal AF patients were revealed to have NCTI-RAT.

Long-term clinical implication of the occurrence of dissociated pulmonary vein activities after circumferential left atrial ablation in patients with paroxysmal atrial fibrillation.

BACKGROUND: The incidence and clinical implication of dissociated pulmonary vein (PV) electrical activities after circumferential antrum PV ablation for paroxysmal atrial fibrillation (AF) remains unclear. METHODS AND RESULTS: A total of 196 patients with symptomatic paroxysmal AF who underwent circumferential antrum PV ablation were prospectively studied. Dissociated PV electrical activities were observed in 101 patients (Group 1), but absent in the remaining 95 patients (Group 2). There were no significant differences in the baseline clinical characteristics between them, except that Group 2 had a higher prevalence of hypertension (30 vs. 44%, P = 0.04). After 21.8 ± 7.9 months of follow-up, 148 had no recurrence of AF after the initial procedure. AF recurrence rate was significantly higher in Group 2 than in Group 1 (P = 0.023). Relapse of PV conduction was the major cause of AF recurrence in both groups (16/16 vs. 19/23, P = 0.08), and the overall procedural success rate after the redo ablation procedure was similar in the 2 groups (90 vs. 86%, P = 0.44). However, the total number of patients with non-PV foci was significantly higher in Group 2 than in Group 1 (12/95 vs. 2/101, P < 0.01). CONCLUSIONS: Dissociated PV electrical activities might identify a subgroup of patients with relatively higher initial procedural success with circumferential PV antrum ablation.