Introduction

Patients with bradyarrhythmias undergo ≈1 million de novo pacemaker implantations annually worldwide.1Since the first pacemaker implantations almost 60 years ago, permanent cardiac pacemaker therapy has evolved remarkably, becoming a minimally invasive treatment, improving the quality of life and reducing the mortality.1-3 Device implantations are now indicated not only for young and middle-aged individuals who need to maintain physical activity, but also for elderly patients and those with a reduced physical function. There is wide recognition that the FC in patients with various cardiovascular diseases is an important risk factor for worsening heart failure and an increased risk of mortality,4, 5 however, there are limited data on whether pacemaker implantations improve the FC, and whether changes in the FC affect the outcomes.
In Japan, there is a system that exempts patients with serious diseases from medical expenses as handicapped disabled patients. In the case of patients with an initial pacemaker implant, the handicapped disability levels can be divided into three levels depending on the indication of the pacemaker implantation defined by the Japanese Circulation Society6 and their FC is determined by the metabolic equivalents (METs). Currently, three years after implanting a pacemaker, the disability level is recertified based on the FC at that time. However, it is not known how the FC changes over time after the initial pacemaker implantation, and therefore, the optimal time for the recertification should be determined by prospective studies. Therefore, the aim of this study was to examine the temporal trends in the FC after a pacemaker implantation and the relationship between the FC and prognosis in patients receiving a de novo pacemaker implantation.