Toward a Prospective Definition of Atrial Fibrillation-induced Cardiomyopathy

Area of Science:

• Cardiology
• Electrophysiology
• Cardiomyopathy Research

Background:

• Atrial fibrillation (AF) is a common arrhythmia linked to left ventricular systolic dysfunction (LVSD).
• AF-induced cardiomyopathy (AIC) involves complex mechanisms beyond just rapid heart rates, necessitating distinct diagnostic and therapeutic approaches.
• Current diagnostic methods for AIC are retrospective, limiting proactive clinical management.

Purpose of the Study:

• To review the multifaceted mechanisms by which AF contributes to LVSD.
• To explore advanced imaging parameters and novel markers for prospectively identifying AIC.
• To discuss the potential of integrating new markers with existing imaging techniques for improved clinical decision-making.

Main Methods:

• Narrative review of existing literature on AF and its impact on ventricular function.
• Discussion of established and emerging imaging modalities (e.g., cardiac MRI, stress echocardiography) for assessing LVSD.
• Introduction and review of the Restitution Threshold Index (RTI) as a novel marker for AF-related ventricular dysfunction.

Main Results:

• AF impairs ventricular function through rapid rate, rhythm irregularity, and impaired atrial contraction, often exploiting underlying structural vulnerabilities.
• Existing imaging parameters like late gadolinium enhancement and contractile reserve offer insights but have limitations.
• The Restitution Threshold Index (RTI) is proposed as a non-parametric marker that considers both ventricular rate and AF's irregularity.

Conclusions:

• Identifying specific mechanisms of AIC is challenging but crucial for effective treatment.
• Integrating the novel RTI marker with imaging-based parameters may improve the prospective identification of patients who would benefit from rhythm control therapies.
• Further validation of RTI is essential for developing accessible clinical tools, with an open-access calculator now available.