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Presentation Time:
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11/15/2005 9:30:00 AM
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Title:
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Predictive Value of Microvolt T-Wave Alternans for Sudden Cardiac
Death in Patients with Preserved Left Ventricular Function after Myocardial
Infarction: Results of a Collaborative Cohort
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Keywords:
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Risk factors,Sudden death,Myocardial
infarction,Electrocardiography,Ventricular arrhythmia
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Author Block:
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Takanori Ikeda, Kyorin University, Tokyo, Japan; Kaoru Sugi, Toho
University, Tokyo, Japan; Hiroki Shimizu, Hyogo College of Medicine,
Nishinomiya, Japan; Jun Watanabe, Tohoku University, Sendai, Japan; Yuji
Kasamaki, Nihon University, Tokyo, Japan; Akihiro Yoshida, Kobe University,
Kobe, Japan; Kaoru Tanno, Showa University, Tokyo, Japan; Hideaki Yoshino,
Kyorin University, Tokyo, Japan; Takao Kato, Nippon Medical School, Tokyo,
Japan
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Disclosure Block:
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T. Ikeda, None; K.
Sugi, None; H. Shimizu, None; J. Watanabe,
None; Y. Kasamaki, None; A. Yoshida, None; K.
Tanno, None; H. Yoshino, None; T. Kato, None.
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Unlabeled/unapproved:
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There are no unlabeled/unapproved uses of drugs or products.
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There are numerous reports regarding risk stratification in patients
with reduced left ventricular ejection fraction (LVEF) after myocardial
infarction (MI). However, few data are available in MI patients with
preserved LVEF. Although prognosis of patients with preserved LVEF is
better than that of patients with reduced LVEF, risk stratification in such
patients is also important in patient care. Microvolt T-wave alternans
(TWA) is associated with increased risk of arrhythmic events in MI
patients. In this study, we conducted a collaborative cohort of patients
with preserved LVEF after MI to evaluate the predictive power of TWA. Methods:
This prospective study enrolled 1012 patients who had LVEF >40%
(average 54±10%) after MI. Patients with persistent atrial fibrillation
were excluded from the study. All patients underwent a TWA testing a mean
of 1.7±2.2 months after acute MI and results were categorized as positive,
indeterminate, or negative. Other 10 prognostic indices such as late
potentials (LP) by signal-averaged electrocardiography and nonsustained
ventricular tachycardia (NSVT) on Holter monitoring were also evaluated in
this population. The primary endpoint was prospectively defined as sudden
cardiac death or cardiac arrest. Results: During a mean follow-up
period of 32±14 months, 37 patients (3.7%) died of nonarrhythmic causes
such as stroke, pneumonia, cancer, and so on. These patients were not
considered for the present analysis. Of the 975 patients, 18 patients
(1.8%) reached one of the primary endpoints. TWA was positive in 167
patients (17%), negative in 724 (74%), and indeterminate in 84 (9%).
Univariate analysis revealed that TWA predicted primary events with a
relative hazard (RH) of 23.2 (P<0.0001). NSVT and LP also had
significant values (RH: 6.2, P=0.0001 and RH: 5.8, P=0.0006,
respectively). To test which index has the most significant value to
predict primary endpoints, we performed multivariate Cox regression
analysis. TWA was the most powerful predictors (RH: 18.9, 95% CI: 5.1-69.3,
P<0.0001). Conclusions: TWA is thus a strong predictor for
sudden cardiac death in patients with preserved LVEF >40% after
acute MI. It may be useful in identifying patients who need implantable
cardioverter defibrillator in this population.
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