Percutaneous ligation of the left atrial appendage results in atrial electrical substrate modification

Long-term effects of left atrial appendage isolation in surgical ablation of atrial fibrillation based on lesion set: a multi-centre propensity-score weighted study

BACKGROUND

This present study aimed to investigate the impact of left atrial appendage (LAA) isolation on adverse clinical outcomes, with a further stratified analysis by biatrial (BA) and left atrial lesion sets, in patients with atrial fibrillation (AF) undergoing surgical ablation (SA) concurrent with mitral valve (MV) surgery.

METHODS

We evaluated 875 patients (aged 65.1±12.0 years) who underwent SA of AF concomitant to MV surgery, excluding those with mechanical prostheses requiring lifelong anticoagulation, between 2005 and 2017 in five tertiary cardiac centres in South Korea. Of these, 458 had isolated the LAA, whereas the remainder (n=417) had the LAA preserved. Comparative risk of stroke, mortality and AF recurrence was assessed between the groups, considering death as a competing event. Inverse-probability treatment weighting was used for baseline adjustment.

RESULTS

During the median follow-up of 57.4 months (IQR, 32.5-92.4 months), the adjusted risk of long-term stroke was significantly lower in the patients who underwent LAA isolation compared with those who preserved the LAA (subdistribution HR (SHR), 0.28; 95% CI 0.15 to 0.51; p<0.001). However, there were no significant differences in the adjusted risk of mortality (HR, 0.85; 95% CI 0.57 to 1.27; p=0.429) or AF recurrence (SHR, 0.92; 95% CI 0.78 to 1.08; p=0.291) between LAA isolation and preservation. In the subgroup of patients who underwent BA ablation, LAA isolation was associated with a lower long-term risk of stroke and AF recurrence (SHR, 0.77; 95% CI 0.61 to 0.94; p=0.029) compared with LAA preservation.

CONCLUSIONS

Concomitant LAA isolation during SA of AF in patients undergoing MV surgery was associated with a significantly lower risk of long-term stroke, but no survival benefit was observed.

Anatomy and Physiologic Roles of the Left Atrial Appendage: Implications for Endocardial and Epicardial Device Closure

The left atrial appendage has been implicated as a major nidus for thrombus formation, particularly in atrial fibrillation. This discovery has prompted substantial interest in the development of left atrial appendage exclusion devices aimed at decreasing systemic thromboembolism risk. Its deceptively simple appearance belies the remarkable complexity that characterizes its anatomy and physiology. We highlight the key anatomic features and variations of the left atrial appendage as well as its relationships with surrounding structures. We also summarize crucial anatomic factors that should be taken into account by the interventional cardiologist when planning for or performing left atrial appendage exclusion procedures.

Electrophysiological Perspectives on Hybrid Ablation of Atrial Fibrillation

To overcome limitations of minimally invasive surgical ablation as a standalone procedure in eliminating atrial fibrillation (AF), hybrid approaches incorporating adjunctive endovascular catheter ablation have been proposed in recent years. The endovascular component targets residual conduction gaps and identifies additional electrophysiological targets with the goal of minimizing recurrent atrial arrhythmia. We performed a systematic review of published studies of hybrid AF ablation, analyzing 432 pooled patients (19% paroxysmal, 29% persistent, 52% long-standing persistent) treated using three different approaches: A. bilateral thoracoscopy with bipolar radiofrequency (RF) clamp-based approach; B. right thoracoscopic suction monopolar RF catheter-based approach; and C. subxiphoid posterior pericardioscopic ("convergent") approach. Freedom from recurrence off antiarrhythmic medications at 12 months was seen in 88.1% [133/151] for A, 73.4% [47/64] for B, and 59.3% [80/135] for C, with no significant difference between paroxysmal (76.9%) and persistent/long-standing persistent AF (73.4%). Death and major surgical complications were reported in 8.5% with A, 0% with B and 8.6% with C. A critical appraisal of hybrid ablation is presented, drawing from experiences and insights published over the years on catheter ablation of AF, with a discussion of the rationale underlying hybrid ablation, its strengths and limitations, where it may have a unique role in clinical management of patients with AF, which questions remain unanswered and areas for further investigation.