Inflammation and Postoperative Atrial Fibrillation in Cardiac Surgery

Postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery, marked by an irregular and rapid heart rate, and associated with increased morbidity, longer hospital stays, and higher costs. Its complex pathophysiology involves atrial remodeling, inflammation, and autonomic dysregulation. Surgical trauma and cardiopulmonary bypass trigger an inflammatory response, releasing cytokines. Epicardial fat around the heart secretes pro-inflammatory cytokines, and its increased thickness is linked to higher inflammation and atrial fibrillation. This study uses RNA sequencing (RNA-seq) to profile gene expression in epicardial fat, identifying key genes involved in inflammation and metabolism. By comparing patients with and without POAF, RNA-seq reveals differentially expressed genes associated with postoperative atrial fibrillation.

Study Overview

• Status: Recruiting
• Conditions: Inflammation; Atrial Fibrillation
• Intervention / Treatment: Other: Descriptive

Detailed Description

Postoperative Atrial Fibrillation (POAF) after Cardiac Surgery Postoperative atrial fibrillation is a common complication following cardiac surgery, characterized by irregular and often rapid heart rate. It is associated with increased morbidity, prolonged hospital stays, and higher healthcare costs. The pathophysiology of POAF is complex and multifactorial, involving atrial structural and electrical remodeling, inflammation, and autonomic dysregulation.

Inflammation and Epicardial Fat Inflammation plays a significant role in the development of POAF. Surgical trauma and cardiopulmonary bypass trigger a systemic inflammatory response, releasing cytokines and other inflammatory mediators. Epicardial fat, the visceral fat depot around the heart, is an active endocrine organ secreting pro-inflammatory cytokines and adipokines. Increased epicardial fat thickness is associated with higher levels of inflammation and has been implicated in the pathogenesis of atrial fibrillation.

RNA isolation and sequencing RNA sequencing (RNA-seq) can be used to investigate gene expression in epicardial fat in several impactful ways. RNA-seq can profile gene expression to identify active genes in epicardial fat and their expression levels, revealing key genes involved in inflammation and metabolism. By comparing gene expression between groups, such as patients with and without POAF, RNA-seq can identify differentially expressed genes associated with atrial fibrillation.

RNA-seq analyses The RNA sequencing data files were aligned to the hg38 reference genome using the Spliced Transcripts Alignment to a Reference (STAR) aligner and read counts in genes were quantified. The resulting data matrix with unnormalized counts was loaded into RStudio together with patient metadata information (e.g., age, gender, BMI, smoking). Differential expression analyses were conducted with DESeq2 using adjustment for different variables, including type of tissue, age of patients, gender, and BMI.

Hypothesis We hypothesize that POAF may be influenced by pre-existing inflammation in epicardial fat, in addition to the inflammation caused by surgical trauma.

Objective:

To compare inflammatory gene expression in epicardial fat between patients who develop POAF and those who do not after elective cardiac surgery.

Study Design:

A prospective cohort study including patients undergoing first-time elective cardiac surgery.

Participants:

Inclusion criteria: Patients undergoing first-time elective cardiac surgery. Exclusion criteria: Patients with previous cardiac surgeries or emergency surgeries.

Groups:

POAF Group: Patients who develop POAF. Non-POAF Group: Patients who do not develop POAF.

Sample Collection:

Epicardial fat samples will be collected during the time of surgery.

RNA Isolation and Sequencing:

Homogenize adipose tissue in TRIzol using ceramic beads (Fastprep 24, MPBio). Purify RNA using EconoSpin columns (Epoch). Prepare RNA libraries with NEBNext Ultra II RNA Library Prep Kit for Illumina. Perform paired-end sequencing on the NovaSeq 6000 platform (Illumina).

Data Analysis:

Align RNA-seq data to the hg38 genome using STAR aligner. Quantify gene counts and perform differential expression analysis using DESeq2. Adjust for variables such as tissue type, age, gender, and BMI.

Outcome Measures:

Compare inflammatory gene expression profiles between POAF and Non-POAF groups at the time of surgery.

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

• Study Contact: Name: Lytfi Krasniqi, MD; Phone Number: 65412404; Email: Lytfi.Krasniqi@rsyd.dk

Study Locations

• Denmark
  • Odense, Denmark, 5000
    • Recruiting
    • Odense University Hospital, Cardiac Surgery Department
    • Contact: Lytfi Krasniqi, MD; Phone Number: 004524638899; Email: Lytfi.Krasniqi@rsyd.dk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

All patients undergoing cardiac surgery

Description

Inclusion Criteria:

• Age > 18
• Informed consent

Exclusion Criteria:

• Incompetent individuals
• General poor health condition at the time of inclusion
• Reoperation

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
POAF; Patients who develop postoperative atrial fibrillation.	Other: Descriptive; This study is observational and does not involve any clinical intervention. The primary procedure involves the collection of epicardial fat tissue samples. The collected samples are then processed and analyzed to compare inflammatory gene expression between the two groups. The analysis includes RNA sequencing to identify differentially expressed genes associated with atrial fibrillation and inflammation.
Non-POAF; Patients who do not develop postoperative atrial fibrillation.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Inflammatory genes	Genes including Interleukin 6	The sample is taken at the time of surgery.

Collaborators and Investigators

• Sponsor: Odense University Hospital

Publications and helpful links

General Publications

• Wong CX, Ganesan AN, Selvanayagam JB. Epicardial fat and atrial fibrillation: current evidence, potential mechanisms, clinical implications, and future directions. Eur Heart J. 2017 May 1;38(17):1294-1302. doi: 10.1093/eurheartj/ehw045.
• Dobin A, Davis CA, Schlesinger F, Drenkow J, Zaleski C, Jha S, Batut P, Chaisson M, Gingeras TR. STAR: ultrafast universal RNA-seq aligner. Bioinformatics. 2013 Jan 1;29(1):15-21. doi: 10.1093/bioinformatics/bts635. Epub 2012 Oct 25.
• Love MI, Huber W, Anders S. Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2. Genome Biol. 2014;15(12):550. doi: 10.1186/s13059-014-0550-8.

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2022
• Primary Completion (Estimated): January 1, 2025
• Study Completion (Estimated): January 1, 2025

Study Registration Dates

• First Submitted: June 20, 2024
• First Submitted That Met QC Criteria: June 20, 2024
• First Posted (Actual): June 26, 2024

Study Record Updates

• Last Update Posted (Actual): June 26, 2024
• Last Update Submitted That Met QC Criteria: June 20, 2024
• Last Verified: June 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Arrhythmias, Cardiac; Inflammation; Atrial Fibrillation
• Other Study ID Numbers: POAF130624

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

Data will be available in anonymized form in accordance with GDPR upon reasonable request.

Data will be shared with researchers whose proposed use has been approved, primarily for replication of our results.

• IPD Sharing Time Frame: TBA
• IPD Sharing Access Criteria: To request access, contact Lytfi.Krasniqi@rsyd.dk. A signed data access agreement, compliant with regional legislation and data authority requirements, is required prior to data release.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No