Introduction: Late potentials (LP) are markers of arrhythmogenic events after myocardial infarction (MI). The localization of LP sources would help to identify arrhythmogenic myocardium. The purpose of this study was to localize these LP sources from non-invasive body surface mapping data.
Methods and results: Six patients were investigated with cardiac MRI and signal averaged 62-lead magnetocardiography after MI. Three of them were suffering from sustained ventricular tachycardia (VT). Sophisticated computer algorithms were used in order to compute the current density on the surface of the left ventricle. We compared these current density distributions for the entire QRS complex and the high frequency LP signals. In the three patients which had premature ventricular complexes (PVCs) we localized the exit sites of these arrhythmias. We found a close matching of the low current density areas based on the QRS complexes and the high current density areas based on the LP signals. These areas predominantly corresponded to sites of the infarctions. Exit sites of PVCs were located close to these areas.
Conclusions: By means of sophisticated computer algorithms we were able to localize LP sources. This would be useful in steering catheter ablation and coronary revascularization therapies. However, the method has to be proven with the help of invasive mapping in a larger number of patients.