This invention relates to a diagnostic test measuring circulating HU proteins or gene transcripts in a blood sample to assess arrhythmic risk in heart failure patients. The invention addresses this need and features a diagnostic/prognostic test for measuring circulating HU levels in a sample to assess arrhythmic risk in heart failure patients, alternatively, to determine the risk of SCD. The methods described herein represent a non-invasive (or minimally invasive) test assay. The methods described herein may also include computing a level of an SCN5A variant, or cardiac transcription factors MESP1 (mesoderm posterior posterior protein 1), or MEF2C (myocyte enhancer factor-2), or any combination thereof.
