Electrocardiogram Changes in the Spectrum of TTNtv Dilated Cardiomyopathy: Accuracy and Predictive Value of a New Index for LV-Changes Identification.

BACKGROUND: Truncating TTN variants (TTNtv) are the main cause of dilated cardiomyopathy (DCM). The dynamic nature of this entity has previously been described. Based on own empirical observations and previous evidences, this study assessed repolarisation patterns and the possible association with morphological and functional status of TTNtv-DCM patients. METHODS: Electrocardiograms (ECGs) of index patients with TTNtv-DCM and their relatives were included and matched in time with an echocardiogram. All individuals were classified into five phenotype groups: 1) Reduced left ventricular ejection fraction (LVEF <50%); 2) Recovered LVEF: at least 10% increase and LVEF >30% after optimal medical treatment; 3) Borderline phenotype (mildly enlarged ventricle and/or hyper-trabeculation); 4) Genotype positive, phenotype negative; and 5) Non-carriers. All electrocardiograms were evaluated by two blinded observers in qualitative and quantitative terms [T index (mm)=Σ T-wave amplitude (V5, V6, II, aVF)] and these data were compared with demographic and clinical information. The Δ T-index was calculated in those individuals with more than one electrocardiogram. RESULTS: Seventy-eight (78) electrocardiograms were included (46% female, mean age 50 years). T-index and prevalence of an abnormal T-wave had significantly different results among the groups (p<0.0001). Age and haemodynamic factors were shown to be ECG-modifiers, especially in phenotype-negative patients. T-index enabled individuals with reduced LVEF (<2.5) to be identified and to differentiate patients with favourable and unfavourable responses to treatment (Δ T index >3.5 and ≤2, respectively). CONCLUSION: Repolarisation changes enabled characterisation of the spectrum of TTNtv-DCM. The T-index identified potential carriers and patients with the worst profiles of the spectrum of the disease.