Abstract 11939: Different Impact of Habitual Physical Activity on Ventricular Repolarization in Middle Aged and Elderly Men and Women: Ikaria Study
Backround: Regular physical activity (PA) has substantial cardiac benefits. QT interval represents the duration of ventricular repolarization and its prolongation is associated with greater mortality risk. Aim of the study was to evaluate the impact of PA on QT duration in a sample of middle aged and elderly individuals of Ikaria island, a place world-wide recognized as having high rates of longevity and low cardiovascular mortality rates.
Methods: We enrolled 1071 inhabitants of Ikaria Island (65±13 yrs, 47% males); Among several demographic and clinical characteristics PA was estimated with IPAQ (low, with expended calories < 4 Kcal/min, moderate with expended calories 4-7 Kcal/min and vigorous with expended calories >7 Kcal/min). QT duration was measured from a 12-lead surface digital recorded electrocardiogram and heart rate-corrected QT (QTc) was calculated using Bazett's formula.
Results: Among participants, 85% reported at least moderate PA levels. Women in the "vigorous" and "moderate" PA level compared to those in the "low" PA level had significantly shorter QTc (408±2 msec vs. 419±2 msec, p=0.002, 411±1 msec vs. 419±2 msec, p=0.002, respectively). In contrast men in the "vigorous" and "moderate" PA level compared to those in the "low" PA level had no significantly shorter QTc (395±2 msec vs. 402±3 msec, p=0.29, 402±2msec vs. 402±3, p=0.99). Furthermore, linear regression analysis revealed that PA level was significantly associated with shorter QTc in women (b=-12.5, p=0.001) even after adjustment for age, BMI, adherence to the Mediterranean diet, smoking status and the presence of cardiovascular disease, hypertension, diabetes mellitus and hypercholesterolemia, while no such association was evident in men. Moreover compared to women in the "low" PA level, women in the "moderate" and "vigorous" PA level had decreased odds of having QTc interval > 450 msec by 70% (OR: 0.29 [0.12, 0.72]) and 80% (OR: 0.18 [0.04, 0.85]) respectively.
Conclusion: Increased PA is associated with shorter QTc interval only in middle aged and elderly women of Ikaria Island irrespectively of habituals or medical conditions, illustrating gender differences in the cardioprotective effect of habitual exercise.
- © 2011 by American Heart Association, Inc.