{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,8]],"date-time":"2026-11-08T00:20:38Z","timestamp":1794097238856,"version":"4.8.0"},"reference-count":0,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"3","content-domain":{"domain":["www.ahajournals.org"],"crossmark-restriction":true},"short-container-title":["Circulation"],"published-print":{"date-parts":[[1991,9]]},"abstract":"<jats:sec>\n                    <jats:title>BACKGROUND<\/jats:title>\n                    <jats:p>The Long QT Syndrome (LQTS) is an infrequently occurring familial disorder in which affected individuals have electrocardiographic QT interval prolongation and a propensity to ventricular tachyarrhythmic syncope and sudden death. We prospectively investigated the clinical characteristics and the long-term course of 3,343 individuals from 328 families in which one or more members were identified as affected with LQTS (QTc greater than 0.44 sec1\/2).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS AND RESULTS<\/jats:title>\n                    <jats:p>The first member of a family to be identified with LQTS, the proband, was usually brought to medical attention because of a syncopal episode during childhood or teenage years. Probands (n = 328) were younger at first contact (age 21 +\/- 15 years), more likely to be female (69%), and had a higher frequency of preenrollment syncope or cardiac arrest with resuscitation (80%), congenital deafness (7%), a resting heart rate less than 60 beats\/min (31%), QTc greater than or equal to 0.50 sec1\/2 (52%), and a history of ventricular tachyarrhythmia (47%) than other affected (n = 688) and unaffected (n = 1,004) family members. Arrhythmogenic syncope often occurred in association with acute physical, emotional, or auditory arousal. The syncopal episodes were frequently misinterpreted as a seizure disorder. By age 12 years, 50% of the probands had experienced at least one syncopal episode or death. The rates of postenrollment syncope (one or more episodes) and probable LQTS-related death (before age 50 years) for probands (n = 235; average follow-up 54 months per patient) were 5.0% per year and 0.9% per year, respectively; these event rates were considerably higher than those observed among affected and unaffected family members.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS<\/jats:title>\n                    <jats:p>Among 232 probands and 1,264 family members with prospective follow-up, three factors made significant independent contributions to the risk of subsequent syncope or probable LQTS-related death before age 50 years, whichever occurred first (Cox hazard ratio; 95% confidence limits): 1) QTc (1.052; 1.017, 1.088), 2) history of cardiac event (3.1; 1.3, 7.2), and 3) heart rate (1.017; 1.004, 1.031). The findings from this prospective longitudinal study highlight the clinical features, risk factors, and course of LQTS.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1161\/01.cir.84.3.1136","type":"journal-article","created":{"date-parts":[[2012,6,11]],"date-time":"2012-06-11T20:01:09Z","timestamp":1339444869000},"page":"1136-1144","update-policy":"https:\/\/doi.org\/10.1161\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":805,"title":["The long QT syndrome. Prospective longitudinal study of 328 families."],"prefix":"10.1161","volume":"84","author":[{"given":"A J","family":"Moss","sequence":"first","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P J","family":"Schwartz","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R S","family":"Crampton","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D","family":"Tzivoni","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E H","family":"Locati","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J","family":"MacCluer","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"W J","family":"Hall","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L","family":"Weitkamp","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G M","family":"Vincent","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"suffix":"Jr","given":"A","family":"Garson","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Rochester School of Medicine and Dentistry, N.Y."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","container-title":["Circulation"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.ahajournals.org\/doi\/pdf\/10.1161\/01.CIR.84.3.1136","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,5,12]],"date-time":"2024-05-12T11:59:24Z","timestamp":1715515164000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ahajournals.org\/doi\/10.1161\/01.CIR.84.3.1136"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1991,9]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1991,9]]}},"alternative-id":["10.1161\/01.CIR.84.3.1136"],"URL":"https:\/\/doi.org\/10.1161\/01.cir.84.3.1136","relation":{},"ISSN":["0009-7322","1524-4539"],"issn-type":[{"value":"0009-7322","type":"print"},{"value":"1524-4539","type":"electronic"}],"subject":[],"published":{"date-parts":[[1991,9]]},"assertion":[{"value":"1991-09-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}