Dantrolene, a RyR channel pore-blocking drug approved for treatment of malignant hyperthermia, exhibited antiarrhythmic effects in some patients with RyR2 mutations (Penttinen et al, 2015) and patients with heart failure (Hartmann et al, 2017) but may be impractical for chronic treatment (Bers, 2017) because direct dantrolene actions were questioned at the single-channel level (Choi et al, 2017). This evidence concerns the gene RYR2 and heart failure.