Heterophile antibody interference in cardiac biomarker testing: mechanisms, pitfalls, and clinical consequences

High-sensitivity cardiac biomarkers have transformed modern cardiology by enabling earlier diagnosis and refined risk stratification in acute coronary syndromes and heart failure. However, increasing analytical sensitivity has also amplified the clinical impact of immunoassay interferences, particularly those caused by heterophile antibodies. These endogenous antibodies can interact with assay antibodies and generate false-positive or false-negative results, most notably in sandwich immunoassays used for cardiac troponins and natriuretic peptides. Persistent, clinically implausible biomarker elevations related to heterophile antibody interference have led to unnecessary invasive procedures, inappropriate pharmacologic treatment, repeated hospital admissions, and prolonged diagnostic uncertainty. Conversely, false-negative results may delay diagnosis, result in inappropriate discharge, and contribute to adverse clinical outcomes in high-risk patients. This review summarizes the immunological basis and analytical mechanisms of heterophile antibody interference, highlights cardiac biomarkers most commonly affected, and outlines key clinical red flags that should prompt suspicion. Practical laboratory strategies include polyethylene glycol precipitation as an initial approach to detect antibody-mediated interference, followed by dilution studies, heterophile blocking reagents, and cautiously interpreted alternative platform testing within assay-specific reference frameworks, together with close clinician-laboratory collaboration. Greater awareness of analytical interference is critical as cardiology becomes increasingly biomarker-driven. Integrating clinical judgment with structured laboratory verification can substantially reduce diagnostic error, improve patient safety, and prevent avoidable healthcare utilization in contemporary cardiovascular practice.