Ambulatory ECG-based T-wave alternans and heart rate turbulence predict high risk of arrhythmic events in patients with old myocardial infarction.
BACKGROUND
Few studies have explored risk stratification of arrhythmic events in patients with ischemic heart diseases according to T-wave alternans (TWA) using modified moving average (MMA) method and heart rate turbulence (HRT).


RESULTS
A retrospective analysis of 63 patients who underwent MMA-based TWA and HRT divided the patients into 3 groups: group-C of 21 controls, group-O of 21 patients with old myocardial infarction (OMI) showing no episodes of sustained ventricular tachyarrhythmia (SVT), and group-V of 21 OMI patients with episodes of SVT who received an implantable cardioverter-defibrillator. Among the 3 groups, positive TWA (>or=65 microV) and impaired HRT were observed most frequently in group-V (P<0.05). Using a logistic regression model, TWA yielded an odds ratio of 4.9 (95% confidence interval: 1.2-19.6, P<0.05), which was the only significant covariate for the incidence of life-threatening ventricular arrhythmias during a mean follow-up of 72 months.


CONCLUSIONS
Patients with OMI showing episodes of SVT have a high risk for cardiac death because of abnormal repolarization and autonomic regulation. The analysis of MMA-based TWA and HRT can be a useful tool for predicting OMI patients at high risk of arrhythmic events.
Maeda
Shingo
S
Department of Cardiology, Yokohama-Minami Kyosai Hospital, Yokohama, Japan. s-maeda@ja2.so-net.ne.jp
Nishizaki
Mitsuhiro
M
Yamawake
Noriyoshi
N
Ashikaga
Takashi
T
Shimada
Hiroshi
H
Asano
Mitsutoshi
M
Ihara
Kensuke
K
Murai
Tadashi
T
Suzuki
Hidetoshi
H
Fujii
Hiroyuki
H
Sakurada
Harumizu
H
Hiraoka
Masayasu
M
Isobe
Mitsuaki
M
D000368:Aged; D000369:Aged, 80 and over; D016757:Death, Sudden, Cardiac / Q000209:etiology* / Q000517:prevention & control; D017147:Defibrillators, Implantable; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality / Q000503:physiopathology; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy