Cologne Cardioversion Study

Implantation of internal defibrillators, capable of monitoring the heart and shocking life threatening arrhythmias back to normal rhythm, for patients with severe heart failure increases the probability of survival. Arrhythmias of the atria of the heart are common in these patients. Administering a direct current electrical shock under anesthesia (cardioversion) is the method of choice to reestablish normal sinus rhythm in this instance. Safety and efficacy of external electrical cardioversion (CV) in patients with ICDs was demonstrated in several studies. Safety of internal cardioversion (shocking the heart back into normal rhythm via the implanted defibrillator) was described in several smaller trials. Performing external instead of internal cardioversion in patients with implanted ICDs is more feasible for most hospitals, as CV can be performed without a programming computer and an additional specialist present, e.g. on the intensive care ward, and device interrogation can be done after CV at the remote ICD/pacemaker clinic. No scientific data on safety and efficacy endpoints comparing internal vs external CV is currently available. The aim of the study is to compare external vs internal electrical cardioversion for atrial arrhythmias and establish a safety and efficacy profile for external and internal cardioversion in large cohort of ICD patients.