T-wave Alternans and Intrathoracic Impedance Measurements
T-wave alternans is a test that is currently being used to risk stratify patients with structural heart disease for sudden cardiac death. The mechanism of T-wave alternans is unclear, but may share a common abnormality with conditions of cardiac fluid overload such as heart failure, which is altered intracellular calcium handling. Current Medtronic implantable defibrillators have the capability of monitoring cardiac fluid status via transthoracic impedance measurements.
The purpose of this study is to determine if a correlation exists between T-wave alternans status and cardiac volume status, as determined by transthoracic impedance measurements. Secondarily, the study seeks to examine the relationship between arrhythmia frequency and T-wave alternans or cardiac volume status.
|Study Design:||Observational Model: Cohort
Time Perspective: Prospective
|Official Title:||T-wave Alternans and Intrathoracic Impedance Measurements|
- Number of Positive Twave Studies and Concurrent Positive Optivol Measurement [ Time Frame: upto 3 years ] [ Designated as safety issue: No ]We wanted to examine whether positive Optivol status corresponded to a higher likelihood of a positive T wave study. The T wave alternans result is determined by a proprietary device that measures T wave and reports the result as negative, positive, or indeterminate. The Optivol measurement is obtained through transthoracic impedance values in the implanted device. We investigated the correlation between Optivol status and T wave alternans status.
|Study Start Date:||August 2008|
|Study Completion Date:||April 2012|
|Primary Completion Date:||April 2012 (Final data collection date for primary outcome measure)|
The study group will include Class III to IV heart failure patients followed in the device clinic that have a chronically implanted (more than 90 days) Medtronic biventricular defibrillator with the ability to monitor intrathoracic impedance.
Other: Congestive heart failure
Spontaneous occurrence of fluid overload.
|United States, New York|
|Columbia University Medical Center|
|New York, New York, United States, 10032|
|Principal Investigator:||Jose M Dizon, MD||Columbia University|