Atrial Fibrillation After Cardiac Surgery: Electrophysiological Mechanism and Outcome

Catheter ablation for patients with anomalous pulmonary venous return and atrial fibrillation: a case report and literature review

Background

Anomalous pulmonary venous return involves the partial or complete absence of a connection between the pulmonary veins and the left atrium. The pulmonary vein potential plays a vital role in atrial fibrillation, and catheter ablation to isolate the pulmonary vein is crucial for treating this condition. However, when anomalous pulmonary venous return is present, it makes ablation more challenging and increases the risk of atrial fibrillation recurrence after the procedure.

Case summary

A 49-year-old man was hospitalized because he had been experiencing occasional palpitations for 2 months. He had previously undergone surgery to repair an atrial septal defect when he was 11 years old, during which an issue with the right inferior pulmonary vein was identified but left unaddressed. Electrocardiography upon admission showed atrial fibrillation. Left atrial computed tomography angiography revealed that following atrial septal repair surgery, the right inferior pulmonary vein drained into the right atrium. The patient underwent transcatheter radiofrequency ablation to electrically isolate the pulmonary vein with anomalous return. After 12 months of follow-up, there was no atrial fibrillation recurrence.

Discussion

When performing catheter ablation for anomalous pulmonary venous return and atrial fibrillation, it is essential to consider ablating the irregular pulmonary vein before surgery. This helps to reduce surgical complications and the likelihood of atrial fibrillation recurrence. This case report highlights the challenges encountered during ablation in patients with atrial fibrillation and anomalous pulmonary venous return. In addition, we have reviewed the literature to offer insights into the development of ablation strategies for similar patients.

The association between low serum calcium level and new-onset atrial fibrillation after coronary artery bypass grafting

OBJECTIVES

This study aims to investigate the relationship between serum calcium (SC) levels and the incidence of postoperative atrial fibrillation (POAF) in patients undergoing coronary artery bypass graft surgery.

METHODS

This retrospective, observational cohort study consecutively enrolled patients undergoing isolated coronary artery bypass grafting in Beijing Anzhen Hospital from January 2018 to December 2021. Patients with a previous history of atrial fibrillation or atrial flutter or requiring concomitant cardiac surgery were excluded. A logistic regression model was used to determine predictors of POAF. Multivariable adjustment, inverse probability of treatment weighting and propensity score matching were used to adjust for confounders. Moreover, we conducted univariable and multivariable logistic regression analyses on preoperative and postoperative SC and ionized SC levels.

RESULTS

The analysis encompassed 12 293 patients. The POAF rate was significantly higher in patients with low SC level than those without (1379 [33.9%] vs 2375 [28.9%], P < 0.001). Low SC level was associated with an increased odds ratio of POAF (odds ratio [95% confidence interval]: 1.27 [1.18-1.37], P < 0.001). Inverse probability of treatment weighting and propensity score matching analyses confirmed the results. The increased POAF rate in low SC level group still existed among subgroup analysis based on different age, sex, body mass index, hypertension, hyperlipidaemia, CHA2DS2-VASc and magnesium.

CONCLUSIONS

Low SC level indicates elevated POAF risk in patients undergoing isolated coronary artery bypass graft surgery even after the adjustment for age, sex, cardiovascular risk factors, echocardiographic parameters and laboratory markers.

Relationship between Serum miR-106 and MYL4 Levels and the Prevalence, Risk Stratification, and Prognosis of Atrial Fibrillation

Objective

To analyze the predictive value of serum microRNA-106 (miRNA-106), miR-106, and myosin light chain 4 (MYL4) levels on the prevalence of atrial fibrillation and to explore the relationship between serum miR-106 and MYL4 and the risk stratification and prognosis of atrial fibrillation, thereby providing basis for them to become clinical targets for the treatment of atrial fibrillation in the future.

Methods

300 patients with atrial fibrillation treated in our hospital from May 2017 to March 2019 were selected as the atrial fibrillation group, and 300 healthy people who came to our hospital for physical examination in the same period were selected as the control group. The general data of the subjects in the two groups were collected. The serum miR-106 level of the subjects in the two groups was detected by fluorescence quantitative polymerase chain reaction (PCR), and the level of MYL4 was detected by enzyme-linked immunosorbent assay (ELISA). The expression of miR-106 and MYL4 in the myocardium was observed by immunohistochemistry. The relationship between the levels of serum miR-106 and MYL4 and the prevalence of atrial fibrillation and the score of atrial fibrillation thromboembolism risk stratification scoring system (cha2ds2) was compared between the two groups. The relationship between serum level of miR-106 and prognosis of patients with atrial fibrillation was analyzed.

Results

The systolic blood pressure, diastolic blood pressure, total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and left anterior descending artery (LAD) in the atrial fibrillation group were significantly higher than those in the control group, while HDL-C and left ventricular ejection fraction (LVEF) were significantly lower than those in the control group (P < 0.01). The level of serum miR-106 in patients with atrial fibrillation was significantly higher than that in the control group, whereas the level of MYL4 was significantly lower than that in the control group (P < 0.01). miR-106 was mainly localized in the cytoplasm, and the positive expression rate of miR-106 was 71.43% (81/115) in patients with atrial fibrillation and 21.74% (25/115) in patients with sinus rhythm. MYL4 was mainly located in the cell membrane and the positive expression rate of MYL4 was 24.35% (28/115) in patients with atrial fibrillation and 64.35% (74/115) in patients with sinus rhythm. With the increase of the severity of atrial fibrillation, the level of serum miR-106 gradually increased and the level of MYL4 gradually decreased, which were statistically significant compared with the control group (P < 0.05). With the increase of miR-106 level and the decrease of MYL4 level, the prevalence of atrial fibrillation gradually increased. With the increase of cha2ds2 score, the level of serum miR-106 increased and the level of MYL4 decreased. The survival rate of patients with miR − 106 ≤ 1.96 was significantly higher than that of patients with miR − 106 > 1.96. The survival rate of patients with MYL4 ≥ 0.24 was significantly higher than that of patients with MYL4 < 0.24. At the same time, TC and LDL-C were included in the analysis. The results showed that the survival rate of patients with TC ≤ 4.5 mmol/L was significantly higher than that of patients with TC > 4.5 mmol/L, and that of patients with LDL-C ≤ 2.6 mmol/L was significantly higher than that of patients with LDL-C > 2.6 mmol/L.

Conclusion

Serum miR-106 and MYL4 levels are closely related to the prevalence of atrial fibrillation, which can reflect the risk of thromboembolism in patients with atrial fibrillation and can be used as a biological indicator to predict the prognosis of patients with atrial fibrillation.

Non-invasive evaluation of new-onset atrial fibrillation after cardiac surgery: a protocol for the BigMap study

Aims

New‐onset atrial fibrillation (NOAF) is the most common complication after cardiac surgery, occurring in 25–50% of patients. It is associated with post‐operative stroke, increased mortality, prolonged hospital length of stay, and higher treatment costs. Previous small observational studies have identified the left atrium as a source of the electrical rotors and foci maintaining NOAF, but confirmation by a large prospective clinical study is still missing. The aim of the proposed study is to investigate whether the source of NOAF lies in the left atrium. The correct identification of NOAF‐maintaining structures in cardiac surgical patients might offer potential therapeutic targets for prophylactic perioperative ablation strategies.

Methods and results

This is a prospective single‐centre observational study of patients developing NOAF after cardiac surgery. The primary outcome is the description of NOAF‐maintaining structures within the atria. Key secondary outcomes include overall mortality, intensive care unit length of stay, hospital–ventilator‐free days, and proportion of persistent NOAF. In NOAF patients, the non‐invasive electrophysiological mapping will be conducted using a 252‐electrode electrocardiogram vest. After mapping, a low‐dose computed tomography scan of the chest will be performed to integrate the electrophysiological mapping results into a 3D picture of the heart. The study will include approximately 570 patients, of whom 30% (n = 170) are expected to develop NOAF. Sample size calculation revealed that 157 NOAF patients are necessary to assess the primary outcome. Patients will be tracked for a total of 5 years.

Conclusions

This is the largest prospective study to date describing the electrophysiological mechanisms of NOAF using non‐invasive mapping.

The Prognostic Potential of Atrial Natriuretic Peptide on the Development of Postoperative Atrial Fibrillation after Cardiac Surgery

Background Postoperative atrial fibrillation (POAF) represents a common complication after cardiac surgery associated with major adverse events and poor patient outcome. Tools for risk stratification of this arrhythmia remain scarce. Atrial natriuretic peptide (ANP) represents an easily assessable biomarker picturing atrial function and strain; however, its prognostic potential on the development of POAF has not been investigated so far.

Methods Within the present investigation, 314 patients undergoing elective cardiac surgery were prospectively enrolled. Preoperative mid-region proANP (MR-proANP) values were assessed before the surgical intervention. Patients were followed prospectively and continuously screened for the development of arrhythmic events.

Results A total of 138 individuals (43.9%) developed POAF. Median concentrations of MR-proANP were significantly higher within the POAF group (p < 0.001). MR-proANP showed a strong association with the development of POAF with a crude odds ratio (OR) of 1.68 per 1 standard deviation (1-SD; 95% confidence interval [CI]: 1.31–2.15; p < 0.001), which remained stable after comprehensive adjustment for confounders with an adjusted OR of 1.74 per 1-SD (95% CI: 1.17–2.58; p = 0.006). The discriminatory power of MR-proANP for the development of POAF was validated by the category-free net reclassification improvement (0.23 [95% CI: 0.0349–0.4193]; p = 0.022) and integrated discrimination increment (0.02 [95% CI: 0.0046–0.0397], p = 0.013).

Conclusion MR-proANP proved to be a strong and independent predictor of the development of POAF. Considering a personalized diagnostic and prognostic preoperative work-up, a standardized preoperative evaluation of MR-proANP levels might help to identify patients at risk for development of POAF after cardiac surgery.