By re-analysis of our cohort of thin-filament HCM patients (Coppini et al. 2014) AF was identified in 10% of patients with sporadic mutations in the cardiac Troponin T gene (TNNT2), while AF occurrence was much higher (25–75%) in patients carrying specific “hot-spot” TNNT2 mutations. Here, TNNT2 is linked to atrial fibrillation.