Electrical storm (ES) in ICD patients, defined as 3 or more appropriate ICD interventions within a time span of 24 hours, is a medical emergency associated with adverse outcome. However, it is debated if ES is only a marker of progressive near end-stage cardiac disease or an ar-rhythmogenic entity on its own. Better understanding and prediction are necessary to manage the burden of ES. The goal of this study is to explore the relation between the presence of fragmented QRS (fQRS) and the manifestation of electrical storm in patients with an ICD for ischemic heart disease. A balanced dataset of 100 patients was considered for this study, where 50 patients with ischemic heart disease and dilated cardiomyopathy present ES. 12-lead ECG signals were analyzed from 3 years before until the moment of ES, divided in 4 visits. The fQRS level in the 12-lead ECG data recorded in each visit was automatically quantified with a score between 0 and 1 for each lead. A Friedman test between the first and last visit for each of the groups showed a significant increase in the average level of fragmentation for the patients presenting ES, absent in the control group. This suggests that there is a trend towards deterioration in fQRS for patients manifesting ES with an ICD for ischemic heart disease.@en