Cardiac arrhythmias impact over 16 million Americans, making precise ICD-10 coding critical for claims accuracy and compliance. With 30% of cardiology denials tied to coding errors, mastering codes like I49.9 (unspecified arrhythmia) or I48.0 (atrial fibrillation) is essential. In this guide, I’ll break down the top 10 cardiac arrhythmia ICD-10 codes, documentation requirements, and 2025 updates to streamline your billing process.