Briana Bohannon (left), Peter Larsson (center), and colleagues reveal that PUFAs with distinct head groups can differentially activate the cardiac I_Ks channels that terminate ventricular action potentials, raising the prospect of personalized treatments for LQTS. The graph (right) shows that, compared with linoleic acid (black), linoleoyl glycine (red) moderately shifts the voltage dependence of I_Ks activation, whereas linoleoyl taurine (green) has a much greater effect, largely because of its lower pK_a.