T-wave Morphology Restitution Dependency with Heart Rate Range and Its Association with Sudden Cardiac Death in Chronic Heart Failure

The index of T-wave morphology restitution (TMR) has recently been presented as a sudden cardiac death (SCD) predictor in a population of chronic heart failure (CHF) patients. This index quantifies the level of variation in the T-wave morphology per RR interval (RRI) increment. The impact of using different definitions of ranges of RRI (T-RRI) and the study of the interaction between TMR and Delta RRI are relevant for both the optimization and the mechanistic interpretation of the index. This study aims to investigate the interaction between Delta RRI and TMR and to assess whether different definitions of Delta RRI (patients-independent or patient-specific) may affect the predictive value of TMR. Holter ECG recordings from 651 patients with CHF, including SCD, victims of other causes and survivors, were analyzed. Mann-Whitney test was used to evaluate significant differences between SCD victims and the rest of patients. In the patient-independent analysis, TMR values only showed significant differences when 0.25s <= Delta RR <= 0.3s, while in the patient-specific analysis TMR values were significantly different when Delta RR >= 0.6 of the maximum RR range, Delta RRmax. In conclusion, the index TMR is a predictor of SCD robust to variations in.RR values evaluated in segments comprising at least 0.6 of Delta RRmax.