Clinical and Structural Factors Affecting Ablation Outcomes in Atrial Fibrillation Patients - A Review

Catheter ablation is an effective and durable treatment option for patients with atrial fibrillation (AF). Ablation outcomes vary widely, with optimal results in patients with paroxysmal AF and diminishing results in patients with persistent or long-standing persistent AF. A number of clinical factors including obesity, hypertension, diabetes, obstructive sleep apnea, and alcohol use contribute to AF recurrence following ablation, likely through modulation of the atrial electroanatomic substrate. In this article, we review the clinical risk factors and the electro-anatomic features that contribute to AF recurrence in patients undergoing ablation for AF.

eNOS3 Genetic Polymorphism Is Related to Post-Ablation Early Recurrence of Atrial Fibrillation

PURPOSE

Previous studies have demonstrated an association between eNOS polymorphisms and atrial fibrillation (AF). We sought to determine whether eNOS polymorphisms are associated with AF recurrence after a radiofrequency catheter ablation (RFCA).

MATERIALS AND METHODS

A total of 500 consecutive patients (56±11 years, 77% male) with paroxysmal (68%) or persistent (32%) AF who underwent RFCA and 500 age, gender-matched controls were genotyped for the eNOS3 single nucleotide polymorphism (rs1799983). AF recurrence was monitored according to 2012 ACC/AHA/ESC guidelines.

RESULTS

The frequencies of the rs1799983 variant alleles (T) in the case and control group were not significantly different (OR 1.05, 95% CI 0.75-1.46, p=0.798). AF patients with rs1799983 variants were more likely to have coronary artery disease or stroke than those without genetic variant at this gene (31.0% vs. 17.3%, p=0.004). During mean 17 months follow-up, early recurrence of AF (ERAF; within 3 months) and clinical recurrence (CR) of AF were 31.8% and 24.8%, respectively. The rs1799983 variant was associated with higher risk of ERAF (OR 1.71, 95% CI 1.06-2.79, p=0.028), but not with CR. ERAF occurred earlier (11±16 days) in variant group than those without variant allele (20±25 days, p=0.016). A multiple logistic regression analysis showed that presence of the rs1799983 variant (OR 1.75, 95% CI 1.07-2.86, p=0.026) and persistent AF were independent predictors for ERAF after AF ablation.

CONCLUSION

The rs1799983 variant of the eNOS3 gene was associated with ERAF, but not with CR, after RFCA. eNOS3 gene variants may have a potential role for stratification of post-ablation management.

Enlargement of the left atrium is associated with increased infiltration of immune cells in patients with atrial fibrillation who had undergone surgery

BACKGROUND

Enlargement of the left atrium (LA) is a risk factor of atrial fibrillation (AF) recurrence after pharmacological and nonpharmacological interventions for AF. However, structural changes associated with LA enlargement have not been fully elucidated.

METHODS

To examine inflammation in the structural changes associated with LA enlargement, human left appendages obtained from 27 patients who underwent cardiac surgery by using the maze procedure were subjected to immunohistochemical analysis.

RESULTS

The extent of interstitial fibrosis increased according to the increase in LA dimension (LAD) as assessed by using ultrasound echocardiography. The extent of the infiltration of CD68-positive macrophages and CD3-positive T cells increased simultaneously according to the increments in LAD. The areas infiltrated by immune cells were positively and significantly correlated with LAD (r (2)=0.58, p<0.01 for CD68; r (2)=0.49, p<0.01 for CD3).

CONCLUSIONS

In the patients with AF, LA enlargement was associated not only with the increase in the extent of interstitial fibrosis but also with the changes in the LA component cells, including an increase in number of immune cells resident in tissues.

Influence of body mass index on recurrence and quality of life in atrial fibrillation patients after catheter ablation: a meta-analysis and systematic review

BACKGROUND

Accumulating evidence has demonstrated that overweight and obesity, expressed as high body mass index (BMI), are associated with the development of atrial fibrillation (AF) and quality of life (QoL) in AF patients. However, the role of high BMI as a risk factor for prognosis and QoL in AF patients undergoing ablation remains controversial.

HYPOTHESIS

We hypothesized that elevated BMI was correlated with AF recurrence and QoL after an ablative procedure.

METHODS

We performed a comprehensive search of PubMed, EMBASE, and the Cochrane Library. Studies were included if they investigated the association of BMI with AF recurrence and QoL after ablation.

RESULTS

Of the 151 articles identified, 12 studies that enrolled 3286 individuals met the inclusion criteria. Overall, compared with normal-BMI patients, AF recurrence occured more frequently in high-BMI patients after ablation (odds ratio: 1.32, 95% confidence interval: 1.17-1.5, P < 0.001). However, the pooled esimate of odds ratio adjusted for multiple confounders did not reach significance. The summary weighted mean difference of BMI between patients with and without recurrence was 0.43 (95% confidence interval: 0.05-0.81, P = 0.027). In addition, QoL scores were significantly lower in high-BMI than in normal-BMI patients before the ablative procedure, whereas the gap of QoL between normal-BMI and high-BMI groups was decreased at follow-up.

CONCLUSIONS

Results of this meta-analysis suggest 2 points, namely that the tight association between overweight/obesity and AF recurrence after ablation may be partly due to other concomitant conditions, and that impaired QoL in high-BMI groups is significantly improved after ablation.

Upstream therapies for management of atrial fibrillation: review of clinical evidence and implications for European Society of Cardiology guidelines. Part II: secondary prevention

Fundamental research into molecular mechanisms of atrial fibrillation (AF) and improved understanding of processes involved in the initiation and maintenance of AF have transformed the traditional approach to its management by targeting only the electrical aspects, usually with antiarrhythmic drugs and, recently, by ablation. The antiarrhythmic potential of upstream therapies, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers (ARBs), statins, and n-3 (ω-3) polyunsaturated fatty acids, extends beyond the benefit of treating underlying heart disease to modifying the atrial substrate and intervening in specific mechanisms of AF. The key target is structural remodelling of the atria, particularly inflammation and fibrosis, although there is evidence to suggest the direct involvement at the ion channel level. Positive clinical reports supported by robust experimental data have suggested that upstream therapies can be valuable strategies for primary prevention of AF in selected patients and have resulted in several class IIA recommendations in the new European guidelines on AF. However, these results have not been consistently replicated in the secondary prevention setting, and several recent randomized controlled studies failed to demonstrate any effect of upstream therapies on AF burden or on major cardiovascular outcomes. Part II of the review summarizes the evidence base for the use of upstream therapies for secondary prevention of AF.

Asymmetric dimethylarginine concentration and recurrence of atrial tachyarrythmias after catheter ablation in patients with persistent atrial fibrillation

PURPOSE

It has been reported that elevation of asymmetric dimethylarginine (ADMA) concentration is involved in atrial fibrillation (AF) process. The purpose of this study was to determine whether ADMA concentration is related to recurrences of AF after catheter ablation.

METHODS

A total of one hundred and thirty-eight patients with persistent AF (49.91 ± 7.23 years), but without known heart disease, who underwent successful mapping and catheter ablation were included. Serum ADMA levels were measured 1 day before the catheter ablation.

RESULTS

After a mean follow-up period of 285 days (range, 98-651 days), 80 (58%) patients underwent the AF recurrence. Comparing with no AF recurrence group, the serum ADMA concentration, left atrial diameter, and persistent duration of AF in patients with AF recurrence group were significantly increased. Left atrial diameter, persistent duration of AF, and the number of non-pulmonary vein ectopy ablation were increased when serum ADMA concentration was elevated. In addition, AF recurrences were significantly increased when serum ADMA concentration was elevated. A multivariable Cox regression analysis demonstrated that the elevated ADMA concentration [hazard ration (95% CI), 4.59 (1.81-11.62); P = 0.001], the left atrial diameter [1.35 (1.18-1.55), P < 0.001], and the number of non-pulmonary vein ectopy ablation [1.94 (1.18-3.18), P = 0.009] were independent factors associated with the AF recurrence after catheter ablation.

CONCLUSIONS

This study demonstrated that (1) serum ADMA concentrations were associated with non-PV ectopies and (2) increased serum ADMA concentrations were associated with higher rate of AF recurrence after catheter ablation in patients with persistent AF, supporting our hypothesis that ADMA might participate in the process of atrial remodeling.

High-sensitivity C-reactive protein as a predictor of atrial fibrillation recurrence after primary circumferential pulmonary vein isolation

BACKGROUND

Atrial fibrillation (AF) recurrence after circumferential pulmonary vein isolation (CPVI) is difficult to predict. Inflammation is associated with the development of AF. Inflammatory markers, such as high sensitivity C-reactive protein (hsCRP), are related to AF development via atrial remodeling. However, it is unknown whether plasma hsCRP concentration before CPVI can be used as a predictor for AF recurrence.

METHODS

A total of 121 patients without structural heart disease who underwent primary CPVI by a single operator were included in the study (paroxysmal/persistent AF: 77/44). Left atrial diameter was measured by transesophageal echocardiography. Plasma hsCRP concentration was determined by enzyme-linked immunosorbent assay. Based on the follow-up outcomes, patients were divided into two groups, a recurrence group and a nonrecurrence group. AF recurrence was defined as AF or atrial flutter or atrial tachycardia episodes lasting for ≥30 s during regular follow-up (>12 months).

RESULTS

A total of 36 (29.8%) patients (paroxysmal/persistent AF: 19 [24.7%]/17 [38.6%]) had AF recurrence in a mean 23 (range, 12-44) month follow-up period. The plasma hsCRP concentration in the recurrence group was significantly higher than that in the nonrecurrence group for all patients (median [quartile range] 2.22 [1.97] mg/L vs 0.89 [1.30] mg/L, P < 0.001), for patients with paroxysmal AF (2.12 [2.78] mg/L vs 0.84 [1.15] mg/L, P = 0.028), and for those with persistent AF (2.29 [1.08] mg/L vs 0.89 [1.53] mg/L, P = 0.005). Multiple logistic regression analyses showed that the higher level of the plasma hsCRP (P < 0.001) was a significant prognostic predictor of AF recurrence, both for patients with paroxysmal AF (P = 0.012) and those with persistent AF (P = 0.003).

CONCLUSION

Plasma hsCRP concentration before CPVI was associated with AF recurrence after primary CPVI procedure for both paroxysmal and persistent AF patients. Plasma hsCRP concentration could play a role in prediction of AF recurrence after primary CPVI.