Characterization of Myocardial Repolarization Reserve in Adolescent Females with XXXX .

@entity1 @entity1164 @entity73 @entity448 @entity1278 @entity1162 @entity943
BACKGROUND: - @entity1 with @entity1278 exhibit abnormal myocardial repolarization and are susceptible to @entity1164 . Exercise testing is useful in unmasking @entity1162 in disorders associated with abnormal repolarization. We characterized QT adaptation during exercise in @entity448 . METHODS AND RESULTS: -Sixty-one adolescent female @entity1 with @entity1278 and 45 age and sex matched healthy volunteers performed symptom-limited cycle ergometry during 12-lead ECG monitoring. Changes in the QT interval during exercise were measured, and QT/RR interval slopes were determined using mixed-effects regression modeling. @entity1 had significantly lower BMI than controls however resting heart rates, and QT/QTc intervals were similar at baseline. @entity1 had shorter exercise times (13.7  4.5 vs 20.6  4.5 min; p<0.001), and lower peak heart rates (159  20 vs 184  9 bpm; p<0.001). The mean QTc intervals were longer at peak exercise in @entity1 [442  29 vs 422  19 msec; p<0.001]. During sub-maximal exertion at comparable heart rates [114  6 vs 115  11 bpm; p=0.54], the QTc interval had prolonged significantly more in @entity1 than controls (37  28 vs 24  25 msec; p<0.016). The RR/ @entity1162 , best described by a curvilinear relationship, was more gradual in @entity1 compared to controls (13.4 [95%CI=12.8-13.9] vs 15.8 [95%CI=15.3-16.4] msec QT change per 10% change in RR interval; p<0.001), and steepest in @entity1 within the highest BMI tertile vs the lowest (13.9 [95%CI=12.9-14.9 vs 12.3 [95% CI=11.3-13.3]; p=0.026). CONCLUSIONS: -Despite the absence of @entity1162 , adolescent anorexic females have impaired repolarization reserve compared to healthy controls. Further study may identify @entity73 as a risk factor for @entity943 in @entity1278 .
