Above: AliveCor's ECG app.Image Credit: AliveCorWhile the step counters and run tracker apps of the world get most of the attention, a growing number of apps in the marketplace are serving serious clinical needs. One is AliveCor‘s AliveECG app, which will soon run an algorithm that detects atrial fibrillation (AF), a serious type of heart arrhythmia that’s often a precursor to stroke.