Systems and methods implemented with an implantable medical device (IMD) are provided for performing cardiac testing while temporarily disabling all or selected antitachyarrhythmia therapy delivery capabilities of the device. An initiation signal indicative of initiation of a cardiac test, such as an electrophysiologic test, is received by the IMD. In response to the test initiation signal, a capability of delivering tachyarrhythmia therapy to a chamber of the heart is temporarily disabled. While the capability of delivering tachyarrhythmia therapy is disabled, the subject heart chamber is monitored in response to electrophysiologic testing. The capability of delivering tachyarrhythmia therapy is automatically re-enabled to ensure availability of tachyarrhythmia therapy after completion or interruption of the electrophysiologic test.