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The Electrocardiographic T-Wave; Reference Values, Heritability And Prognostic Significance In Myocardial Infarction


Christian E. Haarmark Nielsen


Thesis:” The Electrocardiographic T‐wave; Reference values, Heritability and Prognostic significance inmyocardial infarction” – by Christian E. Haarmark NielsenThe QT interval has traditionally been used as marker of cardiac repolarization. However because of the QTintervals’ high heart rate dependence, and the fact that a prolonged QT interval is not always associated withan increased arrhythmia risk, other indices of repolarization have been investigated. The main focus has beenon T‐wave derived variables, as the T‐wave directly reflects ventricular repolarization. T‐wave morphologyanalysis, which also includes other features than amplitude and polarity, such as duration, area and slopes, hasbeen shown to reflect arrhythmic vulnerability and risk of cardiovascular morbidity and mortality.However little is known about these T‐wave morphology parameters. The aim of this thesis was to describereference values in a healthy population, age‐, gender‐ and heart rate dependence, inheritance and prognosticcapability in a contemporary PCI‐treated myocardial infarction.Based on a material of 1100 ECGs from a healthy population, we have produced reference values concerning Twavemorphology such as amplitude, area, slope, duration and distribution. Furthermore we have shown thatalthough the majority of these T‐wave variables do have a significant age, gender and heart rate dependence,this is less than the widely used QTcB. The interval from the top of the T‐wave to the end of the T‐wave (TpTeinterval)and the distribution variable skewness and kurtosis were independent of age, gender and heart rate(Study I). In a large sample of twins we have shown that T‐wave amplitude and TpTe interval have a significantheritance even when including covariates such as age, gender and BMI (Study II). In a smaller series of patientswith first time ST‐segment elevation myocardial infarction treated with PCI, TpTe‐interval over 100 msecmeasured before intervention predicted subsequent all‐cause mortality during 22±7 months of follow up(Study III).

In conclusion, T‐wave morphology is a novel and promising way of characterizing repolarization, and selectedT‐wave morphology variables have minimal age, gender and heart rate dependence, significant heritance andcan be used as a prognostic marker in patients with myocardial infarction treated with PCI.