Techniques are provided for detecting stroke within a patient using an implantable medical device. In one example, various electrocardiac and physiological signals are sensed within the patient by the implantable device. The device derives a set of indices from the sensed signals based on parameters affected by stroke. Stroke is then detected within the patient based on an examination of the set of indices. Warnings can then be generated, neurostimulation delivered, pacing therapy adjusted, medications dispensed, etc., in response to the stroke. In one particular example, the set of indices includes: a heart rate variability index a heart rate turbulence index a baroreflex index a QT index a respiration index and a circadian variability index, from which a composite stroke index is derived. Time delta indices may also be generated for each individual index, which are exploited in generating the composite stroke index.
