AGE-RELATED FEATURES AND VARIABILITY OF THE QTC INTERVAL AMONG APPARENTLY HEALTHY MEN BASED ON 24-HOUR HOLTER MONITORING

Background. The QTc interval is an important electrophysiological marker of ventricular repolarization. Its prolongation is associated with an increased risk of life-threatening ventricular arrhythmias and sudden cardiac death. Despite numerous studies, data on age-related features and reference values of QTc parameters obtained from 24-hour Holter monitoring in apparently healthy men, particularly in the Ukrainian population, remain limited. The relevance of this study is determined by the need to establish reliable reference values for accurate interpretation of ambulatory ECG monitoring results and differentiation between physiological age-related changes and pathological conditions. Methods. Eighty-seven 24-hour Holter ECG recordings of apparently healthy men aged 18–82 years (mean age 58.7 ± 16.6 years) were analyzed. Participants were divided into four age groups: 18–43, 46–59, 60–74, and 76–82 years. QT interval correction was performed using Bazett's formula. The following parameters were analyzed: mQTc (mean QTc), QTcmax, QTcmin, and ΔQTc (daily variability). Body mass index (BMI) was calculated and its influence on QTc parameters was assessed. Statistical analysis was performed using IBM SPSS Statistics 25 software. Results. The mean mQTc in the entire cohort was 413.2 ± 16.5 ms (median 413 ms). The highest mean mQTc was observed in the 46–59 years group (425.1 ± 14.2 ms). In older age groups (60–82 years), mean mQTc remained relatively stable, while daily variability (ΔQTc) and QTcmax significantly increased (up to 205.1 ± 64.7 ms and 539.8 ± 31.6 ms, respectively). There was no significant correlation between mQTc and age (r = –0.021). The 95th percentile of mQTc was 445 ms. mQTc values exceeding 450 ms were recorded in only 2.3% of men. Mean BMI was 28.83 ± 4.51 kg/m² and showed no significant correlation with any QTc parameters. Conclusions. In apparently healthy men, mean mQTc remains relatively stable throughout adult life, whereas repolarization variability (ΔQTc) significantly increases with age. The upper limit of normal mQTc is proposed to be 445 ms (95th percentile). The obtained results clarify age-specific reference values of QTc in Ukrainian men, highlight the diagnostic value of 24-hour Holter monitoring, and can be used in clinical practice to improve the accuracy of ambulatory ECG interpretation.