Proteomic Analysis of the Left Atrial Appendage in Atrial Fibrillation

Introduction: Atrial fibrillation (AF) poses a challenge to our growing elderly population; a significant proportion of AF patients are misclassified by clinical categorization. We performed a proteomic analysis of the left atrial appendage tissue obtained from patients suffering from AF subtypes (paroxysmal, persistent, and long-standing persistent).

Methods: MALDI imaging mass spectrometry (MALDI-IMS) was used to differentiate and classify the appendage tissue resected routinely during the MAZE procedure via direct (in situ) analysis of formalin-fixed paraffin embedded (FFPE) tissue samples.

Results: Using receiver operating characteristic analysis (AUC > 0.7) characteristic intensity distribution of given m/z values, which are discriminative for the considered cluster, was determined to distinguish between paroxysmal versus persistent AF, and persistent versus long-persistent AF (persistent vs. long-standing persistent, p = 0.02).

Conclusion: The tissue-based proteomic approach provides clinically relevant information that will be beneficial in improving the risk stratification in AF patients. In the future the obtained information might be considered as new biomarker to support the diagnosis of the severity of AF status. They also suggest new criteria to determine the most appropriate surgery for each AF subtype to improve postoperative outcomes.