MICROVOLT T-WAVE ALTERNATION AS RISK MARKER OF LIFE-THREATENING VENTRICULAR TACHYARRHYTHMIAS IN PATIENTS WITH DILATED CARDIOMYOPATHY
The purpose is study of microvolt T-wave alternations (mTWA) with other known risk markers of fatal ventricular tachyarrhythmias: heart rate turbulence (HRT), QT dispersion in patients with dilated cardiomyopathy (DCM).
Material and methods: We studied 94 patients with DCM (73,5% male; 49,2±11 years; NYHA class 3,09±0,3; QRS 117±32ms; LVEF 25,6±3,9%, sinus rhythm). All pts by Holter ECG-monitoring and 7minutes ECG12 recording (Intecard7), including 5 min of rest and 2 min of exercise test (25Wt\m, heart rate 106±9) were examined. We analyzed ventricular ectopic activity, HRT, mTWA and QTdisp. Pts were divided on two groups: 38 pts with ventricular tachyarrhythmias (nonsustained ventricular tachycardia - 32 pts., spontaneous sustained ventricular tachycardia - 3 pts., ventricular flutter - 3 pts) and 56 without life-threatening arrhythmias or with infrequently premature ventricular ectopy (PVEct<10/hour). There was no significant difference in age, gender between two groups.
Results: Overall, positive mTWA (n=53), pathological QT dispersion (n=64) and positive HRT (nTO=46; nTS=21) were related to male gender (p= 0,01), lower LVEF (p= 0,04) and increased LV end-diastolic volume (p<0,01). Pts with ventricular tachyarrhythmias had significantly higher values of QTdisp (99±13,9ms vs 73±11ms; p<0,001), width QRS (139±19ms vs 99±14ms, p<0,001), mTWA (77,8±9,45mcV vs 46,7±8,32mcV; p<0,001) and higher LV end-diastolic volume (323±76,4 ml vs 254±68,9 ml; p<0,001). After multivariate analysis only positive mTWA remained significant (p=0,03). Chanse identification mTWA in pts with ventricular tachyarrhythmias (VTA) was 0,936; chanse of mTWA in pts without VTA-events was 0,120. The odds ratio was significant - 7,8. Receiver Operating Characteristic curve analysis identified mTWA 56mcV (S 0,96; 95% CI: 0,89-1,07; p=0,0001) as independent predictive marker of life-threatening ventricular tachyarrhythmias.
Conclusions: The study demonstrated value mTWA 56 mcV as an independent predictors of life-threatening VTA events. The odds ratio of identification pathological mTWA in pts with VTA events in comparison to those without VTA was 7,8.