Improved pacemaker technology has permitted application in more diverse groups of patients. A more recently described subset appears to be those with reentrant tachycardias treatable with antiarrhythmic drugs. Here, pacing offers the ability both to test the efficacy of a drug regimen and to provide adjunctive "fail-safe" therapy for those with episodic breakthrough. With the advent of more sophisticated devices, especially those with cardioversion/defibrillation capability, we anticipate a growing interest in these applications which will undoubtedly benefit patients.