Diagnostic Investigation of Sudden Cardiac Event Risk

This is a prospective, multi-center, observational study. The research will be performed in
three phases, each using distinct patient cohorts:

Phase I: Discovery - genes/biomarkers/clinical factors Phase II: Algorithm Development Phase
III: Assay Validation

The final algorithm (Assay) may incorporate a combination of factors including genetic
markers, biomarker(s), and clinical factor(s). Participation in the study does not alter
clinical care. The procedures required by the protocol are collection of a research blood
sample (at baseline only) and interviews with the subject to collect specific clinical
information at baseline and follow-up (6 mos, 1 yr, 2 yr, 3 yr, 4 yr, and 5 yr) after
enrollment. All other data collected is in accordance with the participating institution's
standard patient care.

Inclusion Criteria:

- Implantable cardiac defibrilIator (ICD) or cardiac resynchronization therapy
defibrillator (CRT-D) implanted for primary prevention

- Left ventricular ejection fraction (LVEF) ≤ 50 %

- Ability to collect clinical follow-up and endpoint information, including device
interrogation data

Exclusion Criteria:

- Congenital heart disease

- Known inherited arrhythmia disorder

- Organ transplantation

- Inability to give informed consent