Cardiac Resynchronization and MIBG Imaging
Trial status: Open for Enrollment
Why is this study being done?
The Specific Aim #1 of this study is to assess, with 123iodine metaiodobenzylguanidine (123I-MIBG imaging), whether CRT rebalances and improves the integrity and function of sympathetic nerve terminals in the failing myocardium. The study will test the hypothesis that resynchronization of biventricular contractility attenuates excessive sympathetic drive, and improves autonomic function and cardiac performance.
The Specific Aim #2 of this study is to determine the relationship between 123I-MIBG labeling of sympathetic activity and physiological measures of cardiopulmonary and autonomic function. This aim is to test the hypothesis that impaired cardiac sympathetic activity, determined by 123I-MIBG imaging will be associated with poorer submaximal exercise gas exchange (higher ventilation - CO2 slopes, low end tidal CO2, reduced oxygen pulse and a more rapid frequency response) as well as reduced heart rate power spectral frequencies, a blunted response to positional changes and a delayed heart rate recovery.
Who is eligible to participate?
Inclusion criteria: Indications for Biv-ICD implantation
1. Chronic moderate to severe CHF (NYHA class II or IV)
2. Left ventricular ejection fraction (LVEF) of 35% or less
3. QRS duration of 120 ms or more
4. On optimized anti-heart failure medical regimen
5. Meet one of the following indications for ICD
- Survivors of cardiac arrest due to ventricular fibrillation (VF) or ventricular tachycardia (VT) or spontaneous sustained VT
- Nonsustained VT with coronary disease, prior myocardial infarction, LVEF 35% or less, and inducible VF or sustained VT at electrophysiologic study
- LVEF of 30% or less with severe coronary artery disease
1. Patient condition is unstable
2. Patient is unable to give informed consent
3. Not feasible for patient to be followed at Mayo Clinic
4. Female in pregnancy and breast feeding