Coronary flow reserve and cardiovascular outcomes: a systematic review and meta-analysis - Kelshiker, M; Seligman, H; Howard, JAMES; Rahman, H; Foley, M; Nowbar, A; Rajkumar, C; Shun-Shin, M; Ahmad, Y; Sen, S; Al-Lamee, R; Cole, G; et al. (European Heart Journal, 2022)