Published online before print April 5, 2004,
doi:10.1161/01.CIR.0000124717.77777.EC
|
||||||||
|
|
||||||||
|
(Circulation. 2004;109:1854-1858.)
© 2004 American Heart Association, Inc.
Clinical Investigation
and Reports
|
Microvolt T-Wave Alternans
as a Predictor of Ventricular Tachyarrhythmias
A Prospective Study Using
Atrial Pacing
Kaoru
Tanno, MD; Syunsho Ryu, MD; Norikazu Watanabe, MD; Yoshino Minoura, MD;
Mitsuharu Kawamura, MD; Taku Asano, MD; Youichi Kobayashi, MD; Takashi
Katagiri, MD
From the Third Department of Internal Medicine,
Showa University, Tokyo, Japan.
Correspondence to Kaoru Tanno, MD, Third Department of Internal Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan. E-mail k-tanno@p02.itscom.ne
Received October 5, 2003; revision received January 9, 2004; accepted
January 14, 2004.
Background— Microvolt T-wave alternans (TWA) is reported
to be closely associated with sudden cardiac death (SCD) and ventricular
tachycardia (VT). Animal experiments revealed that microvolt TWA is
highly dependent on heart rate. The purpose of this study was to
determine whether patients with TWA at relatively low heart rates
have increased vulnerability to ventricular tachyarrhythmias.
Methods and Results— Subjects were 248 consecutive
patients (158 men, 90 women; mean age, 59±17 years) who underwent
electrophysiological study from 1997 to 2000. TWA recording was
made in sinus rhythm and at atrial pacing rates of 90, 100, 110, and
120 bpm with the Cambridge Heart CH2000 system. Alternans voltage (Valt)
was measured when the alternans ratio was >3 for a period of
>1 minute in VM, X, Y, Z, or 2 adjacent precordial leads. Study
end point was the first appearance of VT, ventricular fibrillation
(VF), appropriate implantable cardioverter-defibrillator therapy
with pacing or shocks, or SCD. During the 37±12-month follow-up
period, 22 patients had sustained VT, and 5 patients died of SCD. In
patients with >1.9-µV Valt at rates of 90, 100, and
110 bpm, the incidence of VT/VF/SCD was 56%, 28%, and 18%,
respectively. Valt of >2.9 µV at a heart rate of 90
bpm had a 70% positive predictive value for VT/VF/SCD. However, when
Valt was <0.9 µV at a rate of 120 bpm, negative
predictive value was 100%.
Conclusions— Patients with TWA at relatively low heart
rates are susceptible to ventricular tachyarrhythmias.
Key Words: death, sudden • heart rate • T-wave alternans •
tachycardia, ventricular • fibrillation, ventricular