AHA
2005 Studies Demonstrate Effectiveness of Microvolt T-Wave Alternans in
Predicting Sudden Cardiac Death Regardless of Ejection Fraction on 2358
patients |
T Wave Alternans Multiple
presentations were given at The American Hospital Association Meeting in
Dallas, Texas: Three prominent presentations, collectively representing 2,358
study patients further validates Microvolt T-Wave Alternans as an independent
predictor of sudden cardiac death and sustained ventricular events regardless
of the patients Ejection Fraction or EF (a measure of the heart's pumping
ability). Dr. Paul Chan, presenting
information from the Lindner Clinical Trials Center in Cincinnati, reported
on 768 consecutively enrolled ischemic SCD-HeFT type patients with an EF of
less than or equal to 35%. In evaluating the predictive ability of Microvolt
T-Wave Alternans the authors concluded that this non-invasive diagnostic test
is a strong and independent predictor of mortality and appropriate ICD
therapy among Madit II and SCD-HeFT eligible patients with ischemic cardiomyopathy. Also reporting on a patient
population with ejection fraction levels of 40% or less, Dr Elizabeth Kaufman
from Case Western Reserve University in Cleveland, Ohio shared results from a
study of 549 heart failure patients. The hypothesis being evaluated was the
predictive ability of "indeterminate" MTWA tests. In this study the
authors concluded that in patients with left ventricular dysfunction an
indeterminate MTWA test predicted death or sustained ventricular arrhythmias
at least as well as a positive test and that conversely, a negative MTWA test
is associated with a very low risk of death or sustained ventricular
arrhythmia. In the third presentation Dr.
Takanori Ikeda from Kyorin University in Tokyo, Japan evaluated seemingly low
risk patients with an ejection fraction equal to or greater than 40% who had
also experienced an acute myocardial infarction or heart attack. In this
prospectively enrolled study of 1,012 patients each patient was evaluated
with 10 different prognostic indicators including Signal Averaged ECG (SAECG)
and non sustained ventricular tachycardia on Holter Monitoring in addition to
MTWA. After performing a multivariate regression analysis MTWA was found to
be the most powerful predictor. The conclusion being that in heart attack
victims with preserved left ventricular ejection fraction, MTWA was not only
a strong predictor of sudden cardiac death but that MTWA may be useful in
identifying patients in this population who need implantable defibrillators. |