Try our beta test site
IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more...

Epidemiology of Long QTand Asian Sudden Death in Sleep

This study has been completed.
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI) Identifier:
First received: May 25, 2000
Last updated: June 23, 2005
Last verified: March 2005
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. .

Cardiovascular Diseases
Heart Diseases
Death, Sudden, Cardiac
Long QT Syndrome

Study Type: Observational

Resource links provided by NLM:

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Study Start Date: February 1993
Estimated Study Completion Date: January 1995
Detailed Description:


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.


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


Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No
No eligibility criteria
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00005367

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
OverallOfficial: Ronald Munger Utah State University
  More Information

Publications: Identifier: NCT00005367     History of Changes
Other Study ID Numbers: 4254
Study First Received: May 25, 2000
Last Updated: June 23, 2005

Additional relevant MeSH terms:
Long QT Syndrome
Cardiovascular Diseases
Heart Diseases
Death, Sudden
Death, Sudden, Cardiac
Pathologic Processes
Heart Arrest
Arrhythmias, Cardiac
Heart Defects, Congenital
Cardiovascular Abnormalities
Congenital Abnormalities processed this record on May 25, 2017