Use of 3-D Blood Pool Scintigraphy to Guide Left Ventricular Pacing Lead Placement in Patients Requiring Cardiac Resynchronization Therapy

Heart failure (HF) has a prevalence of five million individuals in the United States.
Approximately 25-30% of patients with HF due to left ventricular (LV) systolic dysfunction
have prolonged QRS. Prolonged QRS duration (>120ms) on ECG in HF patients is associated with
increased morbidity and mortality.

Delayed electrical activation of the LV translates to temporal delay in ventricular
contraction. This is referred to as mechanical dyssynchrony. Patients with advanced HF, low
ejection fraction (EF) of less than 35% and QRS of more than 120ms are indicated for cardiac
resynchronization therapy (CRT). While most patients undergoing CRT implantation show
dramatic improvement in HF symptoms, 30-40% of the HF patients undergoing CRT placement do
not show a clinical response. The site of placement of the LV lead has been shown to be an
important determinant of the effects of CRT.

Measurement of left ventricular ejection fraction (LVEF) is performed using non-invasive
measures such as the MUGA. By using the available information on left ventricular systolic
function the investigators plan on investigating the effects of MUGA-guided versus
traditional LV lead placement for CRT.

Inclusion Criteria:

- Male or female, 18 years or older

- Must have an approved indication for CRT implantation

- Must have ischemic or nonischemic dilated cardiomyopathy

- Must have symptomatic HF with a New York Association (NYHA) Classification of III or
IV

- Must be on optimal pharmacological therapy (this should include at the minimum, ACE
inhibitor and beta-blocker therapy as tolerated.

- Must have left ventricular ejection fraction (LVEF) of ≤35%

- Must have ventricular conduction delay manifested as a QRS duration of >120msec

- Must be able to provide informed consent for study participation and be willing to
comply with follow-up tests and scheduled visits

Exclusion Criteria:

- HF diagnosis for less than 3 months

- Physical limitations to ambulation

- Life expectancy of less than six months

- Pregnant or planning for pregnancy in the next 6 months (must have a negative
pregnancy test 7 days prior to enrollment)