<jats:title>ABSTRACT</jats:title><jats:sec><jats:title>Purpose</jats:title><jats:p>Internationally-adopted variant interpretation guidelines from the American College of Medical Genetics and Genomics (ACMG) are generic and require disease-specific refinement. Here we developed CardioClassifier (<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://www.cardioclassifier.org">www.cardioclassifier.org</jats:ext-link>), a semi-automated decision-support tool for inherited cardiac conditions (ICCs).</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>CardioClassifier integrates data retrieved from multiple sources with user-input case-specific information, through an interactive interface, to support varian interpretation. Combining disease- and gene-specific knowledge with variant observations in large cohorts of cases and controls, we refined 14 computational ACMG criteria and created three ICC-specific rules.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>We benchmarked CardioClassifier on 57 expertly-curated variants and show full retrieval of all computational data, concordantly activating 87.3% of rules. A generic annotation tool identified fewer than half as many clinically-actionable variants (64/219 vs 156/219, Fisher’s <jats:bold>P</jats:bold>=1.1x10-18), with important false positives; illustrating the critical importance of disease and gene-specific annotations. CardioClassifier identified putatively disease-causing variants in 33.7% of 327 cardiomyopathy cases, comparable with leading ICC laboratories. Through addition of manually-curated data, variants found in over 40% of cardiomyopathy cases are fully annotated, without requiring additional user-input data.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>CardioClassifier is an ICC-specific decision-support tool that integrates expertly curated computational annotations with case-specific data to generate fast, reproducible and interactive variant pathogenicity reports, according to best practice guidelines.</jats:p></jats:sec>