Does Left Atrial Appendage Amputation During Routine Cardiac Surgery Reduce Future Atrial Fibrillation and Stroke?

The left atrial appendage closure by surgery 2 trial: statistical analysis plan for a randomized multicenter trial exploring if the closure of the left atrial appendage during open-heart surgery reduces stroke irrespective of patients' stroke risk and preoperative atrial fibrillation status

BACKGROUND

Surgical left atrial appendage (LAA) closure concomitant to open-heart surgery prevents thromboembolism in high-risk patients. Nevertheless, high-level evidence does not exist for LAA closure performed in patients with any CHA2DS2-VASc score and preoperative atrial fibrillation or flutter (AF) status-the current trial attempts to provide such evidence.

METHODS

The study is designed as a randomized, open-label, blinded outcome assessor, multicenter trial of adult patients undergoing first-time elective open-heart surgery. Patients with and without AF and any CHA2DS2-VASc score will be enrolled. The primary exclusion criteria are planned LAA closure, planned AF ablation, or ongoing endocarditis. Before randomization, a three-step stratification process will sort patients by site, surgery type, and preoperative or expected oral anticoagulation treatment. Patients will undergo balanced randomization (1:1) to LAA closure on top of the planned cardiac surgery or standard care. Block sizes vary from 8 to 16. Neurologists blinded to randomization will adjudicate the primary outcome of stroke, including transient ischemic attack (TIA). The secondary outcomes include a composite outcome of stroke, including TIA, and silent cerebral infarcts, an outcome of ischemic stroke, including TIA, and a composite outcome of stroke and all-cause mortality. LAA closure is expected to provide a 60% relative risk reduction. In total, 1500 patients will be randomized and followed for 2 years.

DISCUSSION

The trial is expected to help form future guidelines within surgical LAA closure. This statistical analysis plan ensures transparency of analyses and limits potential reporting biases.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT03724318. Registered 26 October 2018, https://clinicaltrials.gov/study/NCT03724318 .

PROTOCOL VERSION

https://doi.org/10.1016/j.ahj.2023.06.003 .

The left atrial appendage closure by surgery-2 (LAACS-2) trial protocol rationale and design of a randomized multicenter trial investigating if left atrial appendage closure prevents stroke in patients undergoing open-heart surgery irrespective of preoperative atrial fibrillation status and stroke risk

BACKGROUND

Current recommendations regarding the use of surgical left atrial appendage (LAA) closure to prevent thromboembolisms lack high-level evidence. Patients undergoing open-heart surgery often have several cardiovascular risk factors and a high occurrence of postoperative atrial fibrillation (AF)-with a high recurrence rate-and are thus at a high risk of stroke. Therefore, we hypothesized that concomitant LAA closure during open-heart surgery will reduce mid-term risk of stroke independently of preoperative AF status and CHA2DS2-VASc score.

METHODS

This protocol describes a randomized multicenter trial. Consecutive participants ≥18 years scheduled for first-time planned open-heart surgery from cardiac surgery centers in Denmark, Spain, and Sweden are included. Both patients with a previous diagnosis of paroxysmal or chronic AF, as well as those without AF, are eligible to participate, irrespective of their CHA2DS2-VASc score. Patients already planned for ablation or LAA closure during surgery, with current endocarditis, or where follow-up is not possible are considered noneligible. Patients are stratified by site, surgery type, and preoperative or planned oral anticoagulation treatment. Subsequently, patients are randomized 1:1 to either concomitant LAA closure or standard care (ie, open LAA). The primary outcome is stroke, including transient ischemic attack, as assigned by 2 independent neurologists blinded to the treatment allocation. To recognize a 60% relative risk reduction of the primary outcome with LAA closure, 1,500 patients are randomized and followed for 2 years (significance level of 0.05 and power of 90%).

CONCLUSIONS

The LAACS-2 trial is likely to impact the LAA closure approach in most patients undergoing open-heart surgery.

TRIAL REGISTRATION

NCT03724318.

Sarcomeric network analysis of ex vivo cultivated human atrial appendage tissue using super-resolution microscopy

Investigating native human cardiac tissue with preserved 3D macro- and microarchitecture is fundamental for clinical and basic research. Unfortunately, the low accessibility of the human myocardium continues to limit scientific progress. To overcome this issue, utilizing atrial appendages of the human heart may become highly beneficial. Atrial appendages are often removed during open-heart surgery and can be preserved ex vivo as living tissue with varying durability depending on the culture method. In this study, we prepared living thin myocardial slices from left atrial appendages that were cultured using an air-liquid interface system for overall 10 days. Metabolic activity of the cultured slices was assessed using a conventional methyl thiazolyl tetrazolium (MTT) assay. To monitor the structural integrity of cardiomyocytes within the tissue, we implemented our recently described super-resolution microscopy approach that allows both qualitative and quantitative in-depth evaluation of sarcomere network based on parameters such as overall sarcomere content, filament size and orientation. Additionally, expression of mRNAs coding for key structural and functional proteins was analyzed by real-time reverse transcription polymerase chain reaction (qRT-PCR). Our findings demonstrate highly significant disassembly of contractile apparatus represented by degradation of [Formula: see text]-actinin filaments detected after three days in culture, while metabolic activity was constantly rising and remained high for up to seven days. However, gene expression of crucial cardiac markers strongly decreased after the first day in culture indicating an early destructive response to ex vivo conditions. Therefore, we suggest static cultivation of living myocardial slices derived from left atrial appendage and prepared according to our protocol only for short-termed experiments (e.g. medicinal drug testing), while introduction of electro-mechanical stimulation protocols may offer the possibility for long-term integrity of such constructs.

Exclusion of left atrial appendage: effects beyond thromboembolic prevention

PURPOSE OF REVIEW

This review aims to summarize the nonthromboembolic prevention effects of left atrial appendage exclusion (LAAE).

RECENT FINDINGS

Left atrial appendage (LAA) secretes multiple hormones; regulates blood volume and pressure; and generates trigger activities. Exclusion of the LAA by different techniques may lead to downstream effects including changes in blood pressure and cardiac performance, improvement of outcome of atrial fibrillation (AF) ablation, and alteration of metabolism.

SUMMARY

LAAE procedures not only prevent thromboembolic events in patients with AF, but rather may bring additional benefits or side-effect to patients undergoing LAAE.

The Effect of Minimally Invasive Thoracoscopic Left Atrial Appendage Excision on Cardiac Dynamic and Endocrine Function

Purpose: Left atrial appendage (LAA) isolation is an effective surgical treatment for decreasing thromboembolic risk. We sought to evaluate the short-term effect of minimally invasive surgery with LAA excision on left atrial dynamic and endocrine function in atrial fibrillation (AF) patients.

Methods: A total of 52 patients with paroxysmal AF undergoing minimally invasive surgery with LAA excision in Anzhen Hospital from October 2012 to June 2014 were enrolled in the study. The natriuretic peptide plasma level was determined by enzyme-linked immunosorbent assay (ELISA), and left atrial dynamic function was measured preprocedure by real-time three-dimensional echocardiography and postprocedure after 7 days and 3 months.

Results: With the exception of six recurrences, 88.5% (46/52) of the patients were prospectively followed over 3 months in terms of their sinus rhythm postprocedure. No severe operative complications or embolism events occurred within those 3 months. Echocardiography showed a 3–6% decrease in left atrial volume postprocedure, and dynamic function was largely restored by 3 months. There was no significant change in natriuretic peptide levels, although a slight decrease was detected 7 days postprocedure, which gradually recovered by 3 months (P = 0.350).

Conclusions: There are no significant differences in left atrial dynamics and natriuretic peptide secretion in AF patients after minimally invasive surgery with LAA excision.

Women and atrial fibrillation

Atrial fibrillation (AF) remains a growing problem in the United States and worldwide, imposing a high individual and health system burden, including increased resource consumption due to repeated hospitalizations, stroke, dementia, heart failure, and death. This comprehensive review summarizes the most recent data on sex-related differences in risks associated with AF. Women with AF have increased risk of stroke and death compared to men, and possible reasons for this disparity are explored. Women also continue to have worse symptoms and quality of life, and poorer outcomes with stroke prevention, as well as with rate and rhythm control management strategies. Many current rhythm control treatment strategies for AF, including cardioversion and ablation, are used less frequently in women as compared to men, whereas women are more likely to be treated with rate control strategies or antiarrhythmic drugs. Sex differences should be considered in treating women with AF to improve outcomes and women and men should be offered the same interventions for AF. We need to improve the evidence base to understand if variation in utilization of rate and rhythm control management between men and women represents health inequities or appropriate clinical judgement.