The sodium-calcium exchanger (NCX) is known as the transporter that controls the concentration of Ca(2+) in cardiac myocytes. In the setting of heart failure and myocardial ischemia-reperfusion, NCX underlies an arrhythmogenic transient inward current responsible for delayed after--depolarizations and nonreentrant initiation of ventricular tachycardia. NCX is an attractive target for treatment in heart failure and myocardial ischemia-reperfusion. We have designed and synthesized a series of phenoxypyridine derivatives, based on compound 3. These derivatives have been evaluated for their inhibitory activity against both the reverse and forward mode of NCX in CCL39 cells. We have discovered several novel potent NCX inhibitors (39q, 48k), which have a high selectivity for reverse NCX inhibitory activity.