The purpose of this study is to determine whether levels of inflammatory markers in circulating blood can correlate with risk for dangerous heart rhythms. Patients with systolic heart failure, which has been shown to increase risk for dangerous heart rhythms, will be enrolled. All subjects will have an implantable cardioverter-defibrillator (ICD) in place, which allows regular evaluation of heart rhythm.

If you agree to be in this study, you will be asked to the following things:

• you will come into the EP device clinic every three months for one year to have your device interrogated and will complete an EKG
• you will have labs drawn to measure levels of certain markers of inflammation in the body. This information will be used to identify new ways to test for risk of abnormal heart rhythms and other heart disease
• you will review your medications with the study coordinator and along with any recent illnesses or hospitalizations

Inclusion Criteria:

• left ventricular ejection fraction [LVEF] <=35%
• ICD implant

Exclusion Criteria:

• Recent myocardial infarction (12 weeks)
• Recent revascularization (12 weeks)
• Recent hospitalization for any cause (6 weeks)
• History of rheumatologic disease

Patients with cardiomyopathy (left ventricular ejection fraction [LVEF] <=35%) who are followed at our institution's ICD device clinic will have levels of circulating biomarkers (hs-CRP, IL-6, TNF-alpha, IL-1, sST2, MMP-1, CICP, CITP) and BNP assessed at three-month intervals for at least one year. Patients will be excluded from the study if they have had a recent myocardial infarction or PCI (within three months), or recent hospitalization.

Patients with obvious primary inflammatory conditions (such as lupus and rheumatoid arthritis) will be excluded. Additionally, significant events (e.g., HF hospitalizations, revascularization, medication changes, and death) will be tracked at each follow up visit for further statistical analysis.