Atrial stunning as predictor of early relapse into atrial fibrillation after cardioversion

Effects of different ablation strategies on long-term left atrial function in patients with paroxysmal atrial fibrillation: a single-blind randomized controlled trial

Restoration of sinus rhythm in atrial fibrillation (AF) by radiofrequency catheter ablation (RFCA) is associated with a transient stunning of left atrial (LA) function. However, the long-term effects of different ablation strategies on LA function remain undetermined. We performed randomized controlled trial to evaluate the effects of RFCA, cryoablation, and 3D mapping-guided cryoablation on LA function of proximal AF patients within 1 year. The 3D mapping-guided cryoablation was defined as a maximum of two cryoablation procedures for each pulmonary vein accompanied by RFCA for additional points until complete pulmonary vein isolation was achieved. Conventional and speckle tracking echocardiographic analyses were performed to evaluate LA function. Among the 210 patients (70 in each group) included, a trend of decreasing LA systolic and diastolic function was observed in all groups, as evidenced by decreases in peak A-wave velocity, the global LA peak systolic strain, the peak strain rate, the peak early diastolic strain rate, and the peak late diastolic strain rate within 7 days to 3 months after ablation followed by gradual recovery thereafter. However, the temporal changes in the above four strain parameters among the three groups did not differ significantly within 1 year after ablation (all p > 0.05). Parameters of the LA emptying fraction and LA dimensions were not significantly affected. These results suggested that stunning of LA function occurred within 7 days to 3 months after ablation, and different strategies of AF ablation did not differentially affect the temporal changes in LA function up to 1 year after ablation.

Effects of Persistent Atrial Fibrillation-Induced Electrical Remodeling on Atrial Electro-Mechanics - Insights from a 3D Model of the Human Atria

Aims

Atrial stunning, a loss of atrial mechanical contraction, can occur following a successful cardioversion. It is hypothesized that persistent atrial fibrillation-induced electrical remodeling (AFER) on atrial electrophysiology may be responsible for such impaired atrial mechanics. This simulation study aimed to investigate the effects of AFER on atrial electro-mechanics.

Methods and Results

A 3D electromechanical model of the human atria was developed to investigate the effects of AFER on atrial electro-mechanics. Simulations were carried out in 3 conditions for 4 states: (i) the control condition, representing the normal tissue (state 1) and the tissue 2–3 months after cardioversion (state 2) when the atrial tissue recovers its electrophysiological properties after completion of reverse electrophysiological remodelling; (ii) AFER-SR condition for AF-remodeled tissue with normal sinus rhythm (SR) (state 3); and (iii) AFER-AF condition for AF-remodeled tissue with re-entrant excitation waves (state 4). Our results indicate that at the cellular level, AFER (states 3 & 4) abbreviated action potentials and reduced the Ca²⁺ content in the sarcoplasmic reticulum, resulting in a reduced amplitude of the intracellular Ca²⁺ transient leading to decreased cell active force and cell shortening as compared to the control condition (states 1 & 2). Consequently at the whole organ level, atrial contraction in AFER-SR condition (state 3) was dramatically reduced. In the AFER-AF condition (state 4) atrial contraction was almost abolished.

Conclusions

This study provides novel insights into understanding atrial electro-mechanics illustrating that AFER impairs atrial contraction due to reduced intracellular Ca²⁺ transients.

Risk factors for recurrence of atrial fibrillation in horses after cardioversion to sinus rhythm

Background

Although atrial fibrillation (AF) can be successfully treated in horses, recurrence occurs frequently. In humans, atrial function after cardioversion can predict recurrence.

Objectives

To examine the prognostic value of atrial mechanical function at 24 hours after cardioversion and other potential predictor variables for AF recurrence in horses.

Animals

117 horses treated for AF at 4 referral centers.

Methods

Retrospective study. Inclusion criteria were successful cardioversion, echocardiography at 24 hours after cardioversion and ≥4 months follow‐up. To determine factors associated with AF recurrence, a multivariable survival model was built.

Results

133 AF episodes in 117 horses were included. AF recurred in 36/100 horses with a first AF episode and in 57/133 AF episodes overall. Factors associated with recurrence in horses with a first episode were previous unsuccessful treatment attempt (hazard ratio HR 2.36, 95% confidence interval CI 1.11–4.99, P = .025) and mild or moderate mitral regurgitation (HR 2.70, 95% CI 1.23–5.91, P = .013). When the last AF episode of all horses was included, previous AF (HR 2.53, 1.33–4.82, P = .005) and active left atrial fractional area change ≤9.6% (HR 3.43, 1.22–9.67, P = .020) were significant predictors.

Conclusions and Clinical Importance

The only echocardiographic variable of left atrial function with significant prognostic value for recurrence was low active left atrial fractional area change. Further research is necessary to evaluate whether echocardiography at a later timepoint could provide more prognostic information.

Serological predictors for the recurrence of atrial fibrillation after electrical cardioversion

BACKGROUND AND OBJECTIVES

Although electrical cardioversion (CV) is effective in restoring sinus rhythm (SR) in patients with atrial fibrillation (AF), AF frequently recurs in spite of antiarrhythmic medications. We investigated the predictors of failed CV and AF recurrence after successful CV.

SUBJECTS AND METHODS

In 81 patients (M:F=63:18, 59.1+/-10.5 years old) with AF who underwent CV, clinical findings and pre-CV serologic markers were evaluated.

RESULTS

During 13.1+/-10.6 months of follow-up, 8.6% (7/81) showed failed CV, 27.16% (22/81) showed early recurrence atrial fibrillation (ERAF; </=2 weeks), 32.1% (26/81) had late recurrence atrial fibrillation (LRAF; >2 weeks), and 32.1% (26/81) remained in SR and had no recurrence (NR). Plasma levels of transforming growth factor beta (TGF)-beta were significantly higher in patients with failed CV than in those with successful CV (p=0.0260). Patients in whom AF recurred were older (60.4+/-9.0 years old vs. 55.3+/-12.5 years old, p=0.0220), and had lower plasma levels of stromal cell derived factor (SDF)-1alpha (p=0.0105). However, there were no significant differences in these parameters between ERAF patients and LRAF patients.

CONCLUSION

Post-CV recurrence commonly occurs in patients aged >60 years and who have low plasma levels of SDF-1alpha. High plasma levels of TGF-beta predict failure of electrical CV.

Clinical and serological predictors for the recurrence of atrial fibrillation after electrical cardioversion

AIMS

Although electrical cardioversion (CV) is effective in restoring sinus rhythm in patients with atrial fibrillation (AF), AF frequently recurs in spite of antiarrhythmic medications. We investigated the predictors of failed CV and AF recurrence after successful CV.

METHODS AND RESULTS

In 81 patients (M:F = 63:18, 59.1 +/- 10.5 years old) with AF who underwent CV, clinical, image, and CV findings (energy requirement, immediate recurrence of AF < 15 min), and pre-CV serological markers were evaluated.

RESULTS

(i) During 13.1 +/- 10.6 months of follow-up, 8.6% (7/81) showed failed CV, 59.26% (48/81) showed AF recurrence, and 32.1% (26/81) remained in sinus rhythm (no recurrence). (ii) Failed CV showed higher plasma levels of transforming growth factor (TGF)-beta (P = 0.0260) than those with successful CV. (iii) Patients with AF recurrence were older (60.4 +/- 9.0 years old vs. 55.3 +/- 12.5 years old, P = 0.0220), had a higher incidence of spontaneous echo contrast (SEC; 68.1 vs. 40.0%, P = 0.0106), a lower prescription rate of angiotensin-converting enzyme inhibitor (ACE-I)/angiotensin receptor blocker (ARB; 27.0 vs. 50.0%, P = 0.0248) or spironolactone (0.0 vs. 19.2%, P = 0.0007), and lower plasma levels of stromal cell-derived factor (SDF)-1alpha (P = 0.0105).

CONCLUSION

Post-CV recurrence commonly occurs in patients with age >60 years, SEC, under-utilization of ACE-I/ARB or spironolactone, and low plasma levels of SDF-1alpha. High plasma level of TGF-beta predicts failed CV.

Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation - the role of atrial cycle length

Background

Atrial electrical remodeling has been shown to influence the outcome the outcome following cardioversion of atrial fibrillation (AF) in experimental studies.

The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF.

Methods

Dominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion.

Results

32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04).

Conclusion

In this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion.