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 Overview

• Status: Completed
• Conditions: Congestive Heart Failure; Arrhythmias
• Intervention / Treatment: Other: Congestive heart failure

• Study Type: Observational
• Enrollment (Actual): 9

Contacts and Locations

Study Locations

• United States
  • New York
    • New York, New York, United States, 10032
      • Columbia University Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Class III or IV heart failure patients

Description

Inclusion Criteria:

• Class III or IV heart failure patients with a chronically implanted Medtronic biventricular defibrillator system capable of monitoring intrathoracic fluid volume.

Exclusion Criteria:

• no active ischemia or pulmonary edema, atrial fibrillation, complete heart block

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Group A; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of Positive Twave Studies and Concurrent Positive Optivol Measurement	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.	upto 3 years

Collaborators and Investigators

• Sponsor: Columbia University
• Collaborators: Medtronic
• Investigators: Principal Investigator: Jose M Dizon, MD, Columbia University

Study record dates

Study Major Dates

• Study Start: August 1, 2008
• Primary Completion (Actual): April 1, 2012
• Study Completion (Actual): April 1, 2012

Study Registration Dates

• First Submitted: April 28, 2008
• First Submitted That Met QC Criteria: April 29, 2008
• First Posted (Estimate): April 30, 2008

Study Record Updates

• Last Update Posted (Estimate): April 19, 2013
• Last Update Submitted That Met QC Criteria: April 11, 2013
• Last Verified: April 1, 2013

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Heart Diseases; Cardiovascular Diseases; Heart Failure
• Other Study ID Numbers: AAAC5529