Left atrial scar identification and quantification in sinus rhythm and atrial fibrillation

Persistent atrial fibrillation without the evidence of low-voltage areas: a prospective randomized trial

BACKGROUND

An effective therapy of persistent atrial fibrillation beyond pulmonary vein isolation remains unsatisfactory. Targeting endocardial low-voltage areas represents an approach of substrate modification. This prospective, randomized study investigated the efficacy of ablation of low-voltage areas versus PVI and additional linear ablations in patients with persistent atrial fibrillation in terms of single-procedure arrhythmia-free outcome and safety.

METHODS AND RESULTS

A total number of 100 patients undergoing de-novo catheter ablation for persistent AF were randomized in a 1:1 ratio into two different treatment arms: group A: pulmonary vein isolation (PVI) and, if low-voltage areas were present, a substrate modification. Group B: PVI and, if atrial fibrillation persisted, additional ablations, such as linear ablation and/or ablation of non-PV triggers. A total of 50 patients were randomized into each group without significant differences in baseline characteristics. During a mean follow-up of 17.64 ± 4.5 months after a single procedure, 34 (68%) patients of group A were free of arrhythmia recurrence versus 28 (56%) patients in group B (p = ns). In group A, 30 (60%) patients did not show endocardial fibrosis and received solely PVI. Both procedures were performed with a low number of complications; no pericardial effusion or stroke were seen in either group.

CONCLUSIONS

A significant proportion of patients with persistent atrial fibrillation do not show low-voltage areas. A total of 70% of the patients receiving solely PVI did not show any recurrence of atrial fibrillation, and therefore, extensive additional ablation should be avoided in de-novo patients.

Uric acid significantly correlates with the presence of low-voltage areas at the endocardial mapping in patients with non-valvular atrial fibrillation

BACKGROUND AND AIMS

Interest in the role of atrial substrate in maintaining Atrial Fibrillation (AF) is growing. Fibrosis is the culprit in the electrical derangement of the myocytes. Many cardiovascular risk factors are known to be linked to atrial scarring; among them Uric Acid (UA) is emerging. The purpose of our study is to find whether UA is associated with Left Atrium (LA) with pathological substrate.

METHODS AND RESULTS

81 patients who underwent radiofrequency transcatheter ablation for nonvalvular AF at the cardiological department of the Niguarda Hospital were enrolled in an observational, cross-sectional, single-center study. UA levels were analysed before the procedure. High density electroanatomic mapping of the LA was performed and patients were divided according to the presence or not of areas of pathological substrate (bipolar voltage <0.5 mV in sinus rhythm). 19 patients showed a LA with pathological substrate. These subjects showed a significant higher prevalence of persistent phenotype of AF (84.2 vs. 25.8%, p < 0.001). UA levels were significantly higher in the group of patients with LA with pathological substrate (6.8 ± 1.9 vs 5.3 ± 1.4 mg/dL, p < 0.001) as well as the prevalence of hyperuricemia (26.5 vs. 6.5%, p = 0.021). The association between uric acid LA with pathological substrate remains significant even after correction for confounding factors (age, left ventricular dysfunction, valvular disease, arrythmia phenotype and furosemide use) and also when the ratio UA/creatinine was evaluated.

CONCLUSIONS

In a population of patients who underwent AF ablation, higher UA levels were significantly associated with pathological LA substrate at electro-anatomical mapping.

Prediction of Left Atrial Fibrosis and Success of Catheter Ablation by Speckle Tracking Echocardiography in Patients Imaged in Persistent Atrial Fibrillation

Background

Non-invasive evaluation of left atrial structural and functional remodeling should be considered in all patients with persistent atrial fibrillation (AF) to optimal management. Speckle tracking echocardiography (STE) has been shown to predict AF recurrence after catheter ablation; however in most studies, patients had paroxysmal AF, and STE was performed while patients were in sinus rhythm.

Aim

The aim of this study was to evaluate the ability of STE parameters acquired during persistent AF to assess atrial fibrosis measured by low voltage area, and to predict maintenance of sinus rhythm of catheter ablation.

Methods

A total of 94 patients (69 men, 65 ± 9 years) with persistent AF prospectively underwent measurement of Global Peak Atrial Longitudinal Strain (GPALS), indexed LA Volume (LAVI), E/e′ ratio, and LA stiffness index (the ratio of E/e′ to GPALS) by STE prior to catheter ablation, while in AF. Low-voltage area (LVA) was assessed by electro-anatomical mapping and categorized into absent, moderate (&gt;0 to &lt;15%), and high (≥15%) atrial extent. AF recurrence was evaluated after 3 months of blanking.

Results

Multivariable regression showed that LAVI, GPALS, and LA stiffness independently predicted LVA extent after correcting for age, glomerular filtration rate, and CHA2DS2-VASc score. Of all the parameters, LA stiffness index had the highest diagnostic accuracy (AUC 0.85), allowing using a cut-off value ≥0.7 to predict moderate or high LVA with 88% sensitivity and 47% specificity, respectively. In multivariable Cox analysis, both GPALS and LA stiffness were able to significantly improve the c statistic to predict AF recurrence (n = 40 over 9 months FU) over CHARGE-AF (p &lt; 0.001 for GPALS and p = 0.01 for LA stiffness) or CHA2DS2-VASc score (p &lt; 0.001 for GPALS and p = 0.02 for LA stiffness). GPALS and LA stiffness also improved the net reclassification index (NRI) over the CHARGE-AF index (NRI 0.67, 95% CI [0.33–1.13] for GPALS and NRI 0.73, 95% CI [0.12–0.91] for LA stiffness, respectively), and over the CHA2DS2-VASc score (NRI 0.43, 95% CI [−0.14 to 0.69] for GPALS and NRI 0.52, 95% CI [0.10–0.84], respectively) for LA stiffness to predict AF recurrence at 9 months.

Conclusion

STE parameters acquired during AF allow prediction of LVA extent and AF recurrence in patients with persistent AF undergoing catheter ablation. Therefore, STE could be a valuable approach to select candidates for catheter ablation.