Systems and methods for electrocardiographic waveform analysis, data presentation and actionable alert generation are described. Electrocardiographic waveform data can be received from a wearable device associated with a patient. A mathematical analysis of at least a portion of the electrocardiographic waveform data can be performed to provide cardiac analytics. In instances where (1) a pathologically prolonged QT interval and (2) an R on T premature ventricular contraction and/or a ventricular tachycardia are detected from the cardiac analytics of the at least a portion of the electrocardiographic waveform data, an actionable alert can be generated and displayed with a visualization of the cardiac analytics.