Systems and methods of verifying that implantable cardiac devices operate as intended in a particular patient involve one or more of determining proper placement of system components, determining stimulus levels useful for individual patient stratification, and determining stimulus levels that indicate efficacy of devices, implantable within a given patient. A pacing stimulus set at a surface pacing level is delivered to a patient's heart using surface electrodes. The patient is determined to not be a candidate for implantation of a subcutaneous defibrillation system if the surface pacing level needed to capture the heart exceeds a predetermined level. The patient may be determined to be a candidate for implantation of a subcutaneous system if the surface pacing level needed to effect capture is within an acceptance level. Such determinations are preferably based on a proportionality relationship between a subcutaneous defibrillation level and a surface pacing level.