1. A computer readable program storage unit encoded with instructions that, when executed by a computer, perform a method for quantifying the quality of a fiducial time marker for a candidate heart beat, comprising: obtaining a fiducial time marker for a candidate heart beat in a first time series of candidate heart beats; setting a beat quality index for said candidate heart beat to a first value; testing said candidate heart beat with a first beat validity test; setting said beat quality index to a second value indicative of whether said first beat validity test was passed; testing said candidate heart beat with a second beat validity test; setting said beat quality index to a third value indicative of whether said second beat validity test was passed; performing at least one responsive action based upon the value of said beat quality index, the responsive action selected from the group consisting of indicating the occurrence of an epileptic seizure event; delivering a neurostimulation therapy to the patient to treat an epileptic seizure event; warning at least one of a caregiver, the patient, or a physician; and logging said beat quality index to a memory.