Usefulness
of T-Wave Alternans for Effective Prophylactic Therapy in Patients with Prior
Myocardial Infarction and Reduced Left Ventricular Ejection Fraction
Takanori Ikeda
Authors: Takao Kato; Yukio Ozawa; Yuji Kasamaki; Yoshio Ohnishi; Jun Watanabe;
Hiroki Shimizu; Kaoru Tanno; Hirokazu Saito; Takanori Ikeda
8:45 - 9:00
Background: Microvolt
T-wave alternans (TWA) has been proposed as a strong predictor for sudden
cardiac death after myocardial infarction (MI). Recently, the MADIT II study
suggested that prophylactic implantation of a defibrillator (ICD) should be
considered as a recommended therapy to improve survival in post MI patients
with a reduced left ventricular ejection fraction (LVEF) ?30%. We assessed whether patients with a prior MI and a LVEF ?30% and a negative TWA test should receive an ICD. Methods: This
prospective study enrolled 82 consecutive MI survivors with a LVEF ?30% that meets MADIT II criteria. Prognostic Indices for arrhythmic
events involved TWA, late potentials (LP) by signal-averaged ECG,
nonsustained ventricular tachycardia (NSVT) on Holter monitoring, age
>70 years, sex (men), anterior wall MI, successful coronary intervention,
coronary bypass surgery, antiarrhythmic drug treatment, and β-blocker
treatment. The primary endpoint was prospectively defined as sudden death,
ventricular fibrillation (VF), and sustained VT. Results: Of 82 MI survivors with a reduced LVEF, TWA
was positive in 48 patients (59%), negative in 25 patients (30%), and
indeterminate in 9 patients (11%). During a mean follow-up period of 720?490 days, 18 patients (22%) reached one of the endpoints; 6 patients
had sudden death or VF, and 12 patients had sustained VT. Of the 10 risk
indices, TWA, LP, and NSVT had significant values with a relative hazard of
9.3 (95%CI 1.2-70.3; p=0.031), 3.5 (95%CI 1.4-8.8; p=0.009), and 4.3 (95%CI
1.7-10.9; p=0.003), respectively. Although 1 of 25 patients with a negative
TWA test had sustained VT, sudden death or VF was not documented in this
patient. When TWA was combined with NSVT, none of patients had arrhythmic
events. TWA had a sensitivity of 94%, a specificity of 52%, a positive
predictive value of 35%, and a negative predictive value of 97%. Conclusions:
These findings demonstrate that post MI patients with a reduced LVEF ?30% and a negative TWA test do not need prophylactic implantation of
an ICD. TWA could contribute to cost-effectiveness in prophylactic therapy
after MI. |