Systems and methods that improving the specificity of discriminating between a monomorphic tachyarrhythmia and a polymorphic tachyarrhythmia are provided that examine frequency content and baseline information of the EGM as discriminatory signatures. Particular algorithms of the present invention that are employed to determine frequency content of the QRS complexes are titled the Slope Distribution Metric (SDM) algorithm and the Slope Distribution Composite (SDC) algorithm.