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.