Evaluating Myocardial Injury for Defibrillation Threshold Testing Methods for ICD Implantation

This is a prospective, randomized (1:1 DFT vs ULV testing), controlled clinical research
trial. Patients undergoing ICD implant or device change out will be candidates for this
study. Medical records for these patients will be screened prior to enrollment to ensure
eligibility for the study. Each patient who is a candidate and who agrees to participate in
the study will undergo the standard of care pre-procedure evaluation including a complete
medical history evaluation, a complete physical examination and routine laboratory testing
including chemistry panel, hematology panel, coagulation panel, a 12-lead electrocardiogram,
and a urine pregnancy test (all females of child-bearing age). A candidate patient will be
randomly assigned to either the standard DFT testing method group or the ULV testing method
group.

For the standard DFT testing group, per routine standard of care, the patient will be
admitted to the hospital. The study requires a pre-procedure blood test of 3 ml for
Troponin-T (TnT) which will be drawn prior to any DFT testing. The blood sample will be sent
to the University of California, San Diego (UCSD) central laboratory for processing. The
patient will then undergo the scheduled ICD implant procedure in a standard fashion. The
standard defibrillation threshold testing will be performed using a low energy shock
delivered on T-wave to induce ventricular fibrillation (VF). If VF is induced, the first
shock is 25J. If success, we will wait 5 minutes and repeat the process. If the 2nd shock
yields success, the DFT testing is complete and a 10J safety margin achieved (device shock
energy is set at 35J or as clinically indicated determined by treating Cardiac
Electrophysiologist). A back-up external defibrillator will always be immediately available
in case transvenous shocks fail. Blood pressure will be monitored before and immediately
after each shock. After 4 hours, 8 hours and 16 hours post DFT testing, blood samples (3 ml
for Troponin-T) will be drawn and sent to the UCSD central laboratory for processing.

For the ULV testing group, per routine standard of care, the patient will be admitted to the
hospital. The study requires a pre-procedure blood test (3 ml for Troponin-T.) which will be
drawn prior to any ULV testing. The blood sample will be sent to the UCSD central laboratory
for processing. The patient will then undergo the scheduled ICD implant procedure as is
standard clinical care. The ULV testing is performed as follows: for single coil device, a
18J shock will be delivered at 0msec, +20 msec, -20msec and -40msec measured from the peak of
the T-wave; for dual coil device, a 18J shock will be delivered at 0msec, -20msec, +20msec,
and +40msec measured from the peak of the T-wave. If VF is not induced with any of the above
mentioned shocks, the ULV will be considered as 18J and the ICD will be implanted with the
first shock strength set at 30 joules or as clinically indicated determined by treating
Cardiac Electrophysiologist. If VF is induced, a 25J rescue shock will be delivered as is
standard and if successful, the device will be programmed to the maximum output of 35 joules
or as clinically indicated determined by treating Cardiac Electrophysiologist. Blood pressure
will be monitored before and immediately after each shock. After 4 hours, 8 hours and 16
hours post ULV testing, blood samples (3 ml for Troponin-T) will be drawn and sent to the
UCSD central laboratory for processing.

Other than the blood tests for Troponin-T, there is no change in routine post-operative
management. Patients will be followed every three months, as is standard management for
patients with ICDs.

The TnT blood draws at 4-hour, 8-hour and 16-hour post implantation will not require longer
hospital stay than is standard for patients undergoing ICD implantation. The results of
Troponin-T measurement for the study patients will be reviewed by the cardiac
electrophysiology (EP) research staff. If myocardial injury is noted (any TnT value >0.1 as
per current assay at the UCSD laboratory), the patient will be monitored as is deemed
clinically necessary by treating Cardiac Electrophysiologist, including possible repeat TnT
measurements for evaluation of myocardial infarction. We will follow standard of care for
management of myocardial injury as recommended by the American Heart Association and the
American College of Cardiology. Elevated TnT measurements may delay hospitalization, if
determined to be clinically necessary. If the repeat TnT measurement is <0.1, then myocardial
injury is most unlikely and the positive TnT value is likely due to DFT shocks.

Inclusion Criteria:

- Patients eligible to receive an ICD implant or change out.

- Patients with a single or dual coil right ventricle (RV) defibrillation lead located
in the RV apex.

- Patients greater than 18 years of age.

- Patients willing and able to give informed consent.

- Patients who have insurance which may cover additional hospital stay if myocardial
injury resulted from testing

Exclusion Criteria:

- Patients with medical conditions that would limit study participation.

- Patients that are pregnant