Abstract 11218: Community Detection of Long QT Syndrome with a Clinical Registry; A Practical Alternative to ECG Screening Programs
Introduction: Community ECG screening programs estimate the prevalence of long QT syndrome (LQTS) at 4/10000. Detection of individuals by such screening is controversial due to the poor sensitivity and specificity of the ECG. An alternative approach is the active identification of probands and screening of family members using a clinical registry. This analysis considers the effectiveness of such an approach in a cardiac/genetic registry in operation for 13 years.
Methods: A consent-based clinical registry for LQTS patients has been in operation in the Northern region of New Zealand (population 2.06 million) since 1999 and has been accompanied by efforts to raise awareness of LQTS. Living probands are referred by pediatric or cardiology services, and unexplained sudden death victims are referred by pathologists. Cascade clinical and genetic screening is carried out in family members to identify presymptomatic individuals at risk. Individuals were defined as either definitely affected (QTc >470ms with unequivocal symptomatology and/or a LQTS-causing mutation) or probably affected (QTc >440ms with repolarisation abnormalities and suggestive symptoms). Every ECG was reviewed by the senior author.
Results: The registry includes 89 probands with definite LQTS. Reasons for referral were: cardiac events (62), ECG abnormalities (7), sudden death (14) or sudden death of a family member (6). A total of 256 definite cases were identified, equating to a prevalence of 1.24/10,000. 228 patients had 77 different LQTS-causing mutations (116 KCNQ1, 77 KCNH2, 32 SCN5A, 1 KCNE1, 2 KCNJ2). If the 68 “probably affected” patients are included, the prevalence increases to 1.57/10,000 and in Auckland City, where the registry is based, overall prevalence is 2.5/10,000.
Conclusion: A high rate of community detection of LQTS is possible using an active program to detect probands and screen their families. In some areas this has detected more than half of the anticipated prevalence. This is a practical alternative to community ECG screening.
- © 2012 by American Heart Association, Inc.