Lower platelet count in healthy centenarians correlates with dispersion of the QT interval.
OBJECTIVE
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 < or = 240,000/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.
Gangemi
Sebastiano
S
School of Allergy and Clinical Immunology, Department of Human Pathology, University of Messina, Messina, Italy.
Basile
Giorgio
G
Merendino
Rosaria Alba
RA
Lo Balbo
Claudia
C
Mento
Antonella
A
Nicita-Mauro
Vittorio
V
Franceschi
Claudio
C
Romano
Mario
M
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001792:Blood Platelets / Q000166:cytology*; D004562:Electrocardiography / Q000706:statistics & numerical data*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008136:Longevity / Q000502:physiology; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000209:etiology / Q000503:physiopathology; D010976:Platelet Count; D012307:Risk Factors; D012802:Sicily; D018709:Statistics, Nonparametric