Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:It involves progressive fibrous and fatty replacement of myocardium in the inflow, apical and outflow portions of the right ventricle, resulting in ventricular tachycardia with incurrent risk of sudden death and in a proportion of cases, progressive RV dysfunction [1-5].
Category: