QT interval dynamicity during exercise test in adolescent athletes. (25th November 2020)

• Record Type: Journal Article
• Authors: Balykova, L; Makarov, L.M; Komolyatova, V.N; Shchekina, N.V; Ivyanskij, S.A; Soldatov, Y.O
• Is Part Of: European heart journal. Volume 41:(2020)Supplement 2
• Publication Date: 2020-11-25
• Subjects: Prevention: Exercise; Cardiology -- Periodicals; Heart -- Diseases -- Periodicals; 616.12005
• DOI: 10.1093/ehjci/ehaa946.2882
• Languages: English
• ISSNs: 0195-668X

Abstract

Abstract: : In search of predictors of the life-threatening arrhythmias, the objective of this research was to study repolarization dynamics and reveal the signs of myocardial electrical instability in young athletes during exercise test (ET). Methods: 124 young athletes including 78 boys 11–16 years old and 50 healthy untrained boys were enrolled into the study. All the children underwent ET with ECG recording and manually evaluated durations of QT interval and its derivatives –QTc interval, calculated by Basett and Fridericia formulas (QTc, FQTc), QTc and FQTc interval dispersion. Rate-dependent QT interval parameters ("QT dynamics") were measured using of linear regression formula for determining slope, intercept, and correlation (r) between QT and RR intervals (Zareba W, Bayes de Luna A, 2005). Results: Initially and on low and moderate loading (25–100 Wt) the athletes had lower heart rate (HR) than in untrained, and quicker (3 min) restoration to initial level (<450 ms) during recovery. The athletes had higher absolute QT interval duration at rest due to bradycardia and myocardial hypertrophy. Beginning step II QTc and FQTc intervals and their dispersions shortening up to minimal in both athlete and untrained groups. Maximal QTc interval in athletes as well as in untrained was recorded at stage I (25 Wt) and did not exceed 460 ms in boys and 470 ms in girls versus 450 and 440 ms, respectively. Maximal QTc prolongation (δQTc) during ET (QTcmax − QTcmin) in athletes did not exceed 80 ms. A shorter FQTc duration compared to QTc was noted. More efficient rate-dependent QT interval reduction ("QT/RR hyperadaptation") was noted in athletes at peak load: the upper limits of normal QTc, FQTc and dQTc were 400, 330 and 14 ms, respectively. These parameters increasing along with other (echocardiographic and biochemical) signs may serve as myocardial remodeling markers. Decreased ("flat") slope QT/RR and lower level of QT/RR correlation ("hypoadaptation of QT to RR") were recorded in athletes at rest and at the initial stages of load, probably due to a higher vagal tone. At the peak load increase both in slope ("steep slope") and correlation QT/RR ("QT/RR hyper-adaptation") was noted. Absence of this phenomenon was observed in athletes with cardiac remodeling. Conclusions: Repolarization dynamics during ET test was similar in athletes and untrained children. Maximal QTc interval in athletes during ET was higher than in untrained and QTc shortening at peak load was more efficient. Complete restoration of HR and QTc intervals to the initial level in athletes occurred at an early recovery period (3 min). Absence of such dynamics gave evidence of myocardial remodeling. Funding Acknowledgement: Type of funding source: None