Relationship of the Implantable Cardioverter Defibrillator and Chronic Resynchronization Therapy: The Perfect Marriage?

Background: The two major modes of death in the patient with a reduced ejection fraction (EF) are death due to heart failure and death due to lethal arrhythmia, essentially the two sides of the same coin. Over the last 20 years, two therapies—cardiac resynchronization therapy (CRT) and the implantable cardioverter defibrillator (ICD)—have been developed and tested in clinical trials. They are now, in conjunction with appropriate medical therapy, the mainstays of therapy for these two commonly encountered clinical problems. Method and Results: Both of these therapies were conceived and patented by two Baltimore cardiologists, Michel Mirowski and Morton Mower ( Table I). The path to everyday acceptance of both therapies was remarkably similar. The concept and early success of both devices was accomplished but the proof of concept depended on a series of carefully designed randomized clinical trials that showed that both the CRT and ICD devices saved lives in the low EF population, especially when used together. These trials overcame substantial skepticism on behalf of elements of the cardiology and electrophysiology establishment. 1 Mirowski/Mower Legacy of Pivotal TherapiesICDCRTConcept 1970 Mid 1970s Patent 1971 1990 First implant 1981 1991 FDA/CMS approval 1984 2004 Pivotal trials MADIT I & II COMPANION SCD‐HeFT CARE‐HF AVIDCIDSICD = implantable cardioverter defibrillator; MADIT = Multicenter Automatic Defibrillator Implantation Trial; COMPANION = Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure; SCD‐HeFT = Sudden Cardiac Death in Heart Failure Trial; AVID = Antiarrhythmics versus Implantable Defibrillator; CIDS = Canadian Implantable Defibrillator Study.Conclusion: We are now at a crossroads in the further extension of either therapy. The majority of the indications for either device alone or in combination are established. In the next few years, assuming the continued commitment on the part of regulatory agencies to fully embrace evidence‐based medicine, we will see indications extended but only by the careful clinical trials that became the bedrock of their initial acceptance.