Deep electrocardiographic classifiers achieve strong performance, but their latent evidence remains difficult to audit. Prevalent explanations usually do not jointly expose clinical semantics, global rules, conflict, and abstention failures. In this work, we propose Cardiac Auditing with Rule-Based Decisions, Interpretability, and Abstention for eXplainability (CARDIA-X), a model-agnostic post-hoc framework that maps frozen neural features to continuous electrocardiogram (ECG) semantics, applies Weighted Entropy-Density Discretization, and induces conflict-aware rough-set rules without retraining. To our knowledge, its scientific novelty is the first governed neural-to-semantic-to-symbolic audit pathway that separately evaluates prediction, reconstruction, rules, fiducials, morphology, and physician agreement. Unlike other state-of-the-art approaches, which are based on local importance, predefined-concept sensitivity, architecture-coupled concepts, or exemplar similarity but not a reusable conflict-aware rulebook for a frozen ECG model, CARDIA-X uniquely combines continuous clinical semantics, symbolic rules, explicit conflict, and reason-coded abstention. On 2,198 patient-disjoint PTB-XL test records, exact multilabel subset accuracy was 0.741, micro-averaged F1 was 0.813, and atrial-fibrillation F1 was 0.875, whereas rare-label F1 ranged from 0.171 to 0.250. Semantic-reconstruction mean absolute error was 0.572, external LUDB R-peak detection achieved F1 of 0.916, and benchmark-blinded physician agreement across 100 cases yielded Cohen's kappa of 0.683. Overall, CARDIA-X enables traceable and clinically interpretable retrospective auditing while providing a rigorous foundation for systematic clinical evaluation and further methodological refinement.