Using Postmortem Formalin Fixed Paraffin-Embedded Tissues for Molecular Testing of Sudden Cardiac Death: a Cautionary Tale of Utility and Limitations

•The validity of molecular testing of a panel of 95 cardiac genes using FFPE samples typically processed by the Medical Examiners was evaluated.•The sequencing results of twelve FFPE samples and the matched nonfixed samples of each case were compared.•FFPE samples that fixed in shorter period (2–6 days) produced higher quality of sequencing results than those fixed in longer period (>29 days).•Up to 52 % false negative & 27 % false positive sequencing results of FFPE samples were identified.•Without the nonfixed samples as control, the testing results of the FFPE samples should be cautioned of false positive and negative errors.