The objective of the study is to collect information on the naturally occurring variations in ST deviations at different heart rates, as detected by the AnalyST and AnalyST Accel Implantable Cardioverter Defibrillators (ICD).

Inclusion Criteria:

• Patient has received or is scheduled to receive a St Jude Medical AnalyST or AnalyST Accel ICD;
• Patient has documented ischemic heart disease.

Exclusion Criteria:

• Patient has an indication for ventricular pacing;
• Patient has chronotropic incompetence or insufficiency;
• Patient has a contraindication to stress testing;
• Patient is physically unable to complete the stress test protocol;
• The patient has persistent or permanent atrial fibrillation (AF);
• Patient is unable to comply with the protocol and follow-up schedule based on geographic location or for any reason;
• Patient is pregnant;
• Patient is minor (< 18 years old).