Background: In this study, we examined how biobank study participants, who were found to have long QT syndrome (LQTS), a potentially life-threatening but treatable cardiac arrhythmia condition, experienced the process of disclosure of unexpected results and referral to health care. Methods: All 27 subjects with a LQTS mutation finding were asked to complete a questionnaire. Four participants did not uptake the re-testing and 5 others did not respond to the questionnaire. We received 17 questionnaires from 6 males and 11 females, aged 46-82; 5 of them were also willing to participate in qualitative interviews. Results: Of the respondents, 16/17 had experienced the process of receiving the results as positive and useful, especially if they had had symptoms. One respondent experienced the process negatively due to concerns related to informing her children. All respondents felt that genetic results should be reported back to the participants, while 2 indicated that this should occur only in the case of treatable conditions. Respondents had informed all of their children about the genetic condition, except 2 minors. Conclusions: The respondents from a population biobank study who were informed about an unexpected genetic finding evaluated this process as mainly positive. They considered that delivering genetic information about a life-threatening but actionable condition has more beneficial than adverse consequences. The feedback policy for biobanks should include how and who is informed, advise treatment or care pathways for actionable findings, and it should also include suitable options for those who do not want to know about such findings.