Aims: Autologous stem cell transplantation has been successfully used for repair of infarcted myocardium, but concerns have been raised regarding its pro-arrhythmic potential. This study aimed at using electrophysiological assessment, and the monitoring and data storage capacity of implanted cardioverter defibrillators (ICDs), in order to evaluate the possible proarrhythmic potential of stem cell transplantation.
Methods: Five patients with a history of previous anteroseptal myocardial infarction and an implanted ICD for ventricular arrhythmias underwent intracoronary transplantation of autologous bone marrow-derived and culture-expanded mesenchymal stem cells in combination with endothelial progenitors.
Results: There was evidence of myocardial repair in three patients in whom segmental left ventricular wall motion improvement was detected on stress echocardiography. Before stem cell transplantation, clinical non-sustained ventricular tachycardia and inducible monomorphic ventricular tachycardia, or ventricular flutter at electrophysiology study were demonstrated in all patients. At 16-36 months follow-up, interrogation of the ICD failed to detect sustained or non-sustained ventricular arrhythmia in any patient. At repeat electrophysiology study, sustained ventricular arrhythmia was induced in two patients.
Conclusion: Intracoronary transplantation of autologous mesenchymal and endothelial progenitor cells does not appear to be arrhythmogenic in humans. Further studies are needed on this important clinical issue.