A device and method to detect slow ventricular tachycardia, deliver anti-tachycardia pacing therapies, and delay a scheduled shock therapy if the ventricular tachycardia is not terminated or accelerated. Preferably, a shock therapy is delayed after verifying hemodynamic stability based on a hemodynamic sensor. After a shock is delayed, the device operates in a high alert mode for redetecting an accelerated tachycardia. Anti-tachycardia pacing therapies are repeated during the shock delay. A number of conditions can trigger delivery of the delayed shock therapy including a specified period of elapsed time; determination that the patient is likely to be asleep; detection of myocardial ischemia; detection of compromised hemodynamics, or detection of a substantially prone position or sudden change in position. A delayed shock therapy may be triggered by the patient and repeated delivery of painful shock therapies in patients that are not seriously compromised by a recurring, slow ventricular tachycardia is avoided.