[Positive microvolt T-wave alternans as a marker of ventricular arrhythmia trigering during cardioverter-defibrillator implantation].
Microvolt T-wave alternans (MTWA) is promising method for noninvasive assessment of arrhythmic risk, but its role hasn't established yet. The aim of this study was to establish the MTWA potency to predict the ventricular arrhythmia triggering during implantable cordioverter-defibrillator (ICD) implantation. Material and metods. The study group consisted of 21 patients, aged 63.0+/-8.0 years; EF was 38.0+/-12.8%. Seventeen of them had a history of myocardial infarction and 4 had non-ischemic cardiomyopathy. The reason for ICD implantation were secondary prevention due to nonfatal cardiac arrest caused by VF/VT in nineteen patients and in two patients ICD was implanted because of unexplained syncope and low EF (< or =35%). All patients underwent VT/VF triggering during device implantation caused by electrophysiological study (EPS). If this proved ineffective aggressive protocol of 50 Hz BURST and T SHOCK was applied. After ICD implantation the following tests were performed: ECG with HR, QRS and QTc evaluation, 24-hour ECG Holter monitoring with HRV assessment and MTWA evaluation during treadmill exercise test. Results. In the group with VT/VF induced by less aggressive protocol (EPS), group I (n = 10) MTWA was present in nine patients, in one the result of MTWA was indeterminate. In the group with VT/VF induced by more aggressive protocol, group II (n = 11) MTWA was present in four patients, indeterminate in four and absent in three. There was a significant (p = 0.017) difference between group I and II in the frequency of positive result of MTWA. There were no differences between the two groups according to time domain parameters of HRV such as SDNN, RMSSD and PNN50 and QTc. There was a significant difference between the two groups in time duration of QRS complexes, 118.9+/-14.7 vs. 105.6+/-11.5 accordingly (p < 0.04). Conclusions. MTWA may help identify patients in whom VTNVF is more easily inducible by electrophysiologic study during ICD implantation. It is easier to induce ventricular arrhythmia when QRS complexes are wider, irrelevant to left ventricular dysfunction and autonomic function of the heart.
Wierzbowski
Robert
R
Klinika Chorób Wewnetrznych i Kardiologii CSK MON. robert.wierzbowski@neostrada.pl
Michałkiewicz
Dariusz
D
Cholewa
Marian
M
Jacewicz
Katarzyna
K
Gniłka
Anna
A
Adamus
Jerzy
J
D000368:Aged; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment; D017180:Tachycardia, Ventricular / Q000150:complications*; D014693:Ventricular Fibrillation / Q000175:diagnosis* / Q000209:etiology*