Left Atrium Size in Elite Athletes.

OBJECTIVES The goal of this study was to perform a meta-analysis of the published literature to investigate the relationship of high levels of exercise training to left atrial (LA) size. BACKGROUND The "athlete's heart" is a series of cardiac adaptations to systematic exercise training and may include LA enlargement. METHODS We conducted a systematic review of English-language studies in MEDLINE and Scopus from inception through April 29, 2014, that reported LA size in elite athletes. RESULTS A total of 54 studies comprising 7,189 elite athletes and 1,375 controls were included. Forty-eight of the 54 studies reported absolute LA diameter in 7,018 athletes and 1,044 controls. Nine of the 54 studies (including 992 athletes and 426 controls) presented LA volume corrected for body surface area. The adjusted weighted mean LA diameter was 4.1 mm greater in athletes overall compared with sedentary controls (p < 0.0001), and LA volume index was 7.0 ml/m(2) greater in athletes than controls (p < 0.01). Compared with controls, LA diameter was 4.6 mm greater in endurance-trained athletes (p < 0.0001), 2.9 mm greater in strength-trained athletes (p < 0.03), 3.5 mm greater in combined strength- and endurance-trained athletes (p < 0.0001), and 4.2 mm greater in athletes with unspecified training (p < 0.02). CONCLUSIONS To our knowledge, this is the largest compilation of studies documenting that elite athletes have larger LA dimensions compared with controls when evaluated by either LA diameter or LA volume corrected for body surface area. The largest average LA diameters were reported in endurance athletes. Physicians evaluating athletes should be aware that the LA is increased in both strength- and endurance-trained elite athletes.