A heart beat is initiated by an electrical wave that propagates through the heart and initiates cardiac contraction Abnormal wave propagation can result in cardiac arrhythmias Arrhythmias which occur in lower chambers of the heart, ventricular tachycardia and fibrillation, can lead to cardiac arrest and sudden cardiac death Currently, there are about 350000 sudden cardiac deaths in Europe each year  In many cases, these dangerous arrhythmias occur because some regions of  cardiac tissue become pathological as a result of myocardial infarction or other forms of heart disease Localisation of these pathological regions in the heart is crucial for the treatment of these arrhythmias  Recently, a novel clinical methodology was developed which allows cardiologists to simultaneously record electrical activity from both surfaces of the heart: endo-epicardial mapping As this electrical activity is a result of three dimensional wave propagation it also contains information about pathological regions located inside myocardial wall  However, recovering such information from these recordings is highly non-trivial We propose to develop a novel methodology for the identification and characterisation of pathological regions of the heart which can be used for treatment or prevention of ventricular tachycardias It will be done by combination of fundamental mathematical methods developed in our group, state-of art biophysical modelling and unique data from a leading clinical group