Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT00005367 |
| Other study ID # |
4254 |
| Secondary ID |
R01HL049432 |
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
February 1993 |
| Est. completion date |
January 1995 |
Study information
| Verified date |
March 2005 |
| Source |
Utah State University |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
To conduct a cross-sectional epidemiologic study of the determinants of prolonged heart rate
corrected QT interval (QTc) among 300 men and 300 woman in the population with the highest
known risk of SUDS: Southeast Asian refugees in Thailand. .
Description:
BACKGROUND:
Sudden and unexplained death in sleep (SUDS) is a leading cause of death of young men in
several Asian populations. The immediate cause is ventricular fibrillation in the absence of
known disease. A strong environmental component may be inferred from the regional nature of
SUDS in groups that are culturally and genetically distinct and the rapid decline in rates of
SUDS after migration of Southeast (SE) Asian refugees to the United States. Risk of SUDS
rises sharply to a peak among men aged 35 years of age, then declines with increasing age. In
a pilot studies of SE Asian refugee men in Thailand with the highest known risk of SUDS, the
investigators documented high-prevalences of prolonged heart rate corrected QT interval
(QTc), thiamine deficiency, hypokalemia, and a positive association between poor thiamine
status, measured by erythrocyte transketolase activity (ETK), and QTc. These limited studies
were unable to precisely quantify the relationship between QTc and thiamine status, lacked
sufficient power to examine the relationship between QTc and hypokalemia, did not include
other electrolytes, and did not address the striking differences in risk of SUDS by sex and
age.
DESIGN NARRATIVE:
The study was cross-sectional in design. During a 14-month period, informed consent was
obtained from subjects selected in an age-stratified random sample of refugees scheduled for
routine medical screening. Blood samples, 12-lead and 24-hour ECGs, and interview data were
collected to test the following hypotheses: (1) mean QTc was greater in men than women, (2)
mean QTc was greater in men aged 30-39 years than in men younger or older; no similar
relationship was expected among women, (3) QTc was positively correlated with poor thiamine
status, measured by erythrocyte transketolase activity, (4-6) QTc was negatively correlated
with serum levels of potassium, magnesium, and total calcium, and (7) QTc was associated with
abnormalities of autonomic control of the heart, as indicated by power spectral analysis of
heart rate variability. Secondary aims included studying interactions of thiamine status and
electrolytes in the prolongation of QTc, dynamic analysis of QT variation by heart rate level
in 24-hr ECGs, and collection of blood specimens for later genetic studies
