Cardiac resynchronization therapy: Current status and near-future prospects

Cardiac resynchronization therapy (CRT) has been established as a standard treatment for heart failure. The effectiveness of CRT has been shown in many clinical trials and realized in actual clinical practice. Nevertheless, underutilization of CRT is a major problem in the treatment of heart failure. One factor leading to underutilization is the existence of CRT non-responders. CRT non-response has been discussed for approximately 20 years, since CRT was introduced. Since the beginning, the CRT non-response rate has been reported to be 30%. However, we are now undergoing a major transformation in the thinking about CRT response. First, heart failure is a progressive disease. Like many medications for heart failure, CRT does not cure the underlying disease of heart failure. Considering the natural course of heart failure, it is easy to understand that there will definitely be non-responders. There might have been misunderstandings about how to determine CRT response. Although CRT is a treatment for heart failure, it does not cure heart failure or myocardial tissue damage. Instead, by correcting conduction disorders and dyssynchrony, it modifies factors that exacerbate heart failure, which contributes to improvement. In addition, it is important to realize that pacing is the only treatment for correcting conduction disorders. Thus, in theory, CRT is an essential treatment for heart failure at any stage, regardless of severity, when it is accompanied by conduction disorder. Here, we consider the current state of CRT and the causes of underutilization. Returning to the origin of CRT, reconsidering the effects of CRT and the thinking about response, and spreading a new way of thinking will lead to the proper utilization of CRT.