Received: 2 July 2018
Accepted: 28 March 2019
First Online: 11 April 2019
Ethics approval and consent to participate
: The Ethics Committee of the Kanagawa Cardiovascular and Respiratory Center approved the study protocol (approval date: January 16, 2018; approved number: KCRC-17-0040), and the need for patient consent was waived because this was a retrospective study and anonymity was secured.
: Not applicable.
: S Ikeda, A Sekine, T Baba, T Katano, E Tabata, R Shintani, S Sadoyama, H Yamakawa, T Oda, R Okuda, H Kitamura, T Iwasawa, and T Takemura declare that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. T Ogura received an honorarium from Boehringer Ingelheim Co., Ltd. and Shionogi & Co., Ltd.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.