Physiological upper limits of left atrial diameter in highly trained adolescent athletes.

blood pressure up to 200 mm Hg during exercise (2). Thus, changes observed in this recent study may not only be due to the increased preload but may be a consequent to the combined volume and pressure overload. I find it hard to agree with the investigators’ claim that as their athletes showed normal LV diastolic filling “it is reasonable to conclude that their LA enlargement represents uniquely the physiologic consequence of chronic exercise training” as opposed to LA enlargement seen in certain pathologic conditions associated with impaired LV compliance or increased afterload (1). We have demonstrated that while athletes may show normal resting LV filling patterns, some, such as weightlifters, may reveal an abnormal response to isometric stress with reduction in E and marked increase in peak A velocity, resembling that seen in the hypertensive group (3). However, in runners the filling pattern remained normal during isometric stress as well (3,4). Hence, isometric and isotonic training affect LV filling differently as revealed during isometric stress testing, although resting patterns may be normal. Therefore, one cannot claim that LA enlargement is due solely to changes in preload, as concluded in the present study, relying only on resting LV filling patterns. Moreover, the involvement of afterload changes during exercise may have determined which of their athletes showed the greatest impact on the LA size depending on the type of exercise they performed.