Chronic arsenic exposure and cardiac repolarization abnormalities with QT interval prolongation in a population-based study.
BACKGROUND
Chronic arsenic exposure is associated with cardiovascular abnormalities. Prolongation of the QT (time between initial deflection of QRS complex to the end of T wave) interval and profound repolarization changes on electrocardiogram (ECG) have been reported in patients with acute promyelocytic leukemia treated with arsenic trioxide. This acquired form of long QT syndrome can result in life-threatening arrhythmias.


OBJECTIVE
The objective of this study was to assess the cardiac effects of arsenic by investigating QT interval alterations in a human population chronically exposed to arsenic.


METHODS
Residents in Ba Men, Inner Mongolia, have been chronically exposed to arsenic via consumption of water from artesian wells. A total of 313 Ba Men residents with the mean arsenic exposure of 15 years were divided into three arsenic exposure groups: low (< or = 21 microg/L), medium (100-300 microg/L), and high (430-690 microg/L). ECGs were obtained on all study subjects. The normal range for QTc (corrected QT) interval is 0.33-0.44 sec, and QTc > or = 0.45 sec was considered to be prolonged.


RESULTS
The prevalence rates of QT prolongation and water arsenic concentrations showed a dose-dependent relationship (p = 0.001). The prevalence rates of QTc prolongation were 3.9, 11.1, 20.6% for low, medium, and high arsenic exposure, respectively. QTc prolongation was also associated with sex (p < 0.0001) but not age (p = 0.486) or smoking (p = 0.1018). Females were more susceptible to QT prolongation than males.


CONCLUSIONS
We found significant association between chronic arsenic exposure and QT interval prolongation in a human population. QT interval may potentially be useful in the detection of early cardiac arsenic toxicity.
Mumford
Judy L
JL
US Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Research Triangle Park, North Carolina 27711, USA. mumford.judy@epa.gov
Wu
Kegong
K
Xia
Yajuan
Y
Kwok
Richard
R
Yang
Zhihui
Z
Foster
James
J
Sanders
William E
WE
D000328:Adult; D001151:Arsenic / Q000032:analysis / Q000633:toxicity*; D018376:Cardiovascular Abnormalities / Q000139:chemically induced / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D004562:Electrocardiography / Q000379:methods; D004781:Environmental Exposure; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D013599:Systole / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
D014874:Water Pollutants, Chemical; D001151:Arsenic