Decrease Microvolt T-wave Alternation as a New Marker of Antiarrhythmic Target Cardiac Resynchronization

Cardiac resynchronization therapy (CRT) is effective treatment for patients with heart failure and ventricular electromechanical dyssynchrony. We aimed to evaluate the effect of CRT on native microvolt T-wave alternans (mTWA) and relation with occurrence of ventricular tachyarrhythmias (VTs).

Methods and results: We included 68 patients (73,5% male; aged 48,7±11,4; NYHA class 3,03±0,29; QRS width 167±28,3ms; LVEF 25,2±7,4%; left bundle branch block; sinus rhythm) with dilated cardiomyopathy (DCM) who had implanted CRT-P (n=39)/CRT-D(n=29). Data were analyzed at baseline and 14,7 ±2,8 months device clinic follow-up. TWA was determined by software Intecard-7 (rest and exercise test 25Wt\min) during native conduction: VVI-40 or 0V0. Assessment of VTs occurrence was performed by Holter monitoring ECG and telemonitoring of devices in 49 (72,1%) responders and 19 (27,9%) non-responders. Decrease of mTWA mean from 52,5 ±14,7 mcV to 28,8±9,22 mcV (p<0,001) was observed after 12 months of CRT. However, decrease of mTWA from 52,9±11,4 mcV to 25,6±8,13 mcV, p <0,001 was noticed in patients with LV reverse remodeling only; there was a significant positive correlation between mTWA and LV systolic-end volumes (r=0.65, p<0,001) and LV diastolic-end volumes (r=0.58, p<0,001) and negative correlation with LVEF (r= -0.64, p<0,001). Patients without VTs events showed significant improvement of LVEF (from 24,5±6,3% to 35,7±4,7%; p<0,001), decrease LV systolic-end volumes (196,7±48,4ml vs 129±38,6ml;p<0,001) and mTWA decrease (from 52,1±11,6mcV to 20,5 ±7,12 mcV, p<0,000). ROC analysis identified cut-off ΔmTWA ≥ -19,7 mcV (S=0,913; AI 95%: 0,849-0,969, р=0,000; 87% sensitivity; 79% specificity) as antiarrhythmic predictor of CRT effective.

Conclusion: Decrease of mTWA in DCM pts after CRT was associated with LV reverse remodeling and indicates reduction of the arrhythmogenic risk; native cut-off ∆mTWA≥-19,7 mcV could be proposed as a new marker of antiarrhythmic target effective CRT.