This document discusses, among other things, a combination pacer/defibrillator that is tailored for bradycardia patients. In one example, its shock-delivery specificity exceeds its sensitivity to shockable ventricular tachyarrhythmias. In another example, its specificity exceeds 95%, or 99%, or even 99.5%. Sensitivity is programmed to a high desired sensitivity value, but only if it can be done without decreasing the specificity below the desired specificity threshold value. This can be conceptualized as "avoiding at all costs" delivering false shocks, even at the expense of failing to deliver a shock to a treatable ventricular tachyarrhythmia. Specificity enhancements include, among other things, inhibiting shock delivery when the patient is breathing or not supine, using multiple channels or a high rate VT/VF detection threshold. The present pacer/defibrillator device could potentially save the lives of bradyarrhythmia patients who are not presently clinically indicated for a defibrillator/pacer, but who have an increased risk of sudden cardiac death due to one or more risk factors.