Kyra Smithlin still remembers the strange flutter in her heart she felt out of the blue in November 2012 — something she’d never experienced before. But it was just before the holidays, and she had no prior heart issues or a family history of heart problems, so she put off getting it checked out. In mid-December of that year, Smithlin was cuddling with her then 9-year-old son Bryce on a Saturday morning when the boy felt her shaking and heard a gasp.