195 Feasibility of measurement of Endocardial T Wave Alternans prior to Onset of Ventricular Arrhythmias in ICDs (ETWAS study)

• Published in: Archives of Cardiovascular Diseases Supplements Vol. 2; no. 1; p. 62
• Main Authors: Maury, Philippe, Pasquié, Jean-Luc, Raczka, Frank, Beck, Lionel, Taieb, Jerome, Duparc, Alexandre, Hallier, Benoit, Qu, Fujian, Shah, Rhiddi, Farazi, Taraneh, Gardères-Rollin, Anne, Delay, Marc, Davy, Jean Marc, Barnay, Claude
• Format: Journal Article
• Language: English
• Published: Elsevier France 2010
• ISSN: 1878-6480
• DOI: 10.1016/S1878-6480(10)70197-X

T wave alternans (TWA) has been demonstrated as a strong predictor of mortality and ventricular arrhythmias. ICD-stored intracardiac electrograms (IEGM) present a unique opportunity for detecting temporal relationship between the occurrence of TWA and spontaneous arrhythmia. The aim of the ETWAS study was to assess the feasibility of detection of TWA preceding the onset of VT/VF in IEGM. 56 implanted patients with St Jude medical ICDs (44 men, 63 ± 12 yo, mean EF 34 ± 15%) were prospectively enrolled and monitored for one year. Thirteen different T wave parameters were extracted from IEGM (T amplitude, T peak time, Bazett and Hodges corrected T peak time, T end time, T duration between baseline crossing and between points of maximal slopes, T peak to T end, maximal ascending and descending slopes, timing of points of maximal slopes and T wave area). Successive beat by beat differences in each parameter in recordings prior to VT/VF were compared to control recordings in the same pts. TWA was considered if beat by beat variations for at least one parameter was significantly higher than baseline with a p value < 0,01. 22 VT/VF episodes (24 ± 13 beats, 71 ± 17 bpm) and 13 baseline (25 ± 9 beats, 72 ± 18) (ns) were analyzed in 12 pts (1,8 episode/ pt). TWA was present before VT/VF onset in 13 episodes (7 pts) with 1 to 9 differing parameters (3 ± 2). Significant beat by beat differences before VT/VF onset were observed in amplitude, timing, slopes, area and duration of the T wave. Amplitude of the beat by beat variations was 3 to10 larger in episodes than in baseline. Paired and unpaired comparisons of the averaged values of beat by beat variations however did not reveal significant difference between baseline and episodes, except for T wave amplitude (0,07 +/– 0,006 vs 0,14 +/– 0,03 mV, p=0.03 paired and 0,04 unpaired). Detection of TWA prior to VT/VF might be useful in predicting imminent arrhythmia occurrence. TWA can be detected before VT/VF onset in more than half of episodes using a simple time-domain technique and multiple T wave measurements. T wave amplitude seems the most discriminant parameter.