Lower platelet count in healthy centenarians correlates with dispersion of the QT interval

Abstract

Background and aims: Centenarians display a lower incidence of vascular ischemic events. A high platelet count and increased QT dispersion (QTd) represents a risk factor for cardiovascular events. The aim of this study was to evaluate platelet count and QTd in healthy centenarians and to establish correlations between these two indices. Methods: 16 healthy centenarians (4 males, 12 females, range 100–105 years) living in a municipality of Eastern Sicily, and 40 healthy control subjects, divided into two groups: group A (N=20), age range 45–65 years, 7 males, 13 females; and group B (N=20), range 65–85 years, 6 males, 14 females, were examined. Platelets were counted using a blood analyzer and QTd was measured in standard 12-lead electrocardiograms. Differences in platelet count were assessed by one-way analysis of variance (ANOVA) and the Bonferroni test. Correlation coefficients between platelet count and QTd were calculated with the Spearman rank test. Results: Centenarians showed a lower platelet count compared with controls, which was significant with respect to older controls, group B (p<0.05). QTd values did not significantly differ between centenarians and controls. A significant correlation between QTd and platelet count was evident in centenarians but not in controls. This correlation became evident in control subjects with a platelet count ≤240000/mm³. Conclusions: We hypothesize that a reduced number of platelets and the maintenance of normal QTd may contribute to extreme longevity and protect centenarians from cardiovascular events.