Prognostic implications of mutation-specific QTc standard deviation in congenital long QT syndrome.

Background: Individual corrected QT interval (QTc) may vary widely among carriers of the same long QT syndrome (LQTS) mutation. Currently, neither the mechanism nor the implications of this variable penetrance are well understood.

Objectives: To hypothesize that the assessment of QTc variance in patients with congenital LQTS who carry the same mutation provides incremental prognostic information on the patient-specific QTc.

Risk factors for recurrent syncope and subsequent fatal or near-fatal events in children and adolescents with long QT syndrome.

Objectives: We aimed to identify risk factors for recurrent syncope in children and adolescents with congenital long QT syndrome (LQTS).

Background: Data regarding risk assessment in LQTS after the occurrence of the first syncope episode are limited.

Methods: The Prentice-Williams-Peterson conditional gap time model was used to identify risk factors for recurrent syncope from birth through age 20 years among 1,648 patients from the International Long QT Syndrome Registry.

Risk for life-threatening cardiac events in patients with genotype-confirmed long-QT syndrome and normal-range corrected QT intervals.

Objectives: This study was designed to assess the clinical course and to identify risk factors for life-threatening events in patients with long-QT syndrome (LQTS) with normal corrected QT (QTc) intervals.

Background: Current data regarding the outcome of patients with concealed LQTS are limited.

Methods: Clinical and genetic risk factors for aborted cardiac arrest (ACA) or sudden cardiac death (SCD) from birth through age 40 years were examined in 3,386 genotyped subjects from 7 multinational LQTS registries, categorized as LQTS with normal-range QTc (≤ 440 ms [n = 469]), LQTS with prolonged QTc interval (> 440 ms [n = 1,392]), and unaffected family members (genotyped negative with ≤ 440 ms [n = 1,525]).

Clinical implications for patients with long QT syndrome who experience a cardiac event during infancy.

Objectives: This study was designed to evaluate the clinical and prognostic aspects of long QT syndrome (LQTS)-related cardiac events that occur in the first year of life (infancy).

Background: The clinical implications for patients with long QT syndrome who experience cardiac events in infancy have not been studied previously.

Methods: The study population of 3,323 patients with QT interval corrected for heart rate (QTc) > or =450 ms enrolled in the International LQTS Registry involved 20 patients with sudden cardiac death (SCD), 16 patients with aborted cardiac arrest (ACA), 34 patients with syncope, and 3,253 patients who were asymptomatic during the first year of life.

Risk factors for aborted cardiac arrest and sudden cardiac death in children with the congenital long-QT syndrome.

Background: The congenital long-QT syndrome (LQTS) is an important cause of sudden cardiac death in children without structural heart disease. However, specific risk factors for life-threatening cardiac events in children with this genetic disorder have not been identified.

Methods And Results: Cox proportional-hazards regression modeling was used to identify risk factors for aborted cardiac arrest or sudden cardiac death in 3015 LQTS children from the International LQTS Registry who were followed up from 1 through 12 years of age.

Long-QT syndrome after age 40.

Background: Previous studies that assessed the risk of life-threatening cardiac events in patients with congenital long-QT syndrome (LQTS) have focused mainly on the first 4 decades of life, whereas the clinical course of this inherited cardiac disorder in the older population has not been studied.

Methods And Results: The risk of aborted cardiac arrest or death from age 41 though 75 years was assessed in 2759 subjects from the International LQTS Registry, categorized into electrocardiographically affected (corrected QT interval [QTc] > or = 470 ms), borderline (QTc 440 to 469 ms), and unaffected (QTc < 440 ms) subgroups. The affected versus unaffected adjusted hazard ratio for aborted cardiac arrest or death was 2.

Long QT syndrome and pregnancy.

Objectives: This study was designed to investigate the clinical course of women with long QT syndrome (LQTS) throughout their potential childbearing years.

Background: Only limited data exist regarding the risks associated with pregnancy in women with LQTS.

Methods: The risk of experiencing an adverse cardiac event, including syncope, aborted cardiac arrest, and sudden death, during and after pregnancy was analyzed for women who had their first birth from 1980 to 2003 (n = 391).

Long QT syndrome in adults.

Objectives: The aims of this study were: 1) to evaluate risk factors influencing the clinical course of mutation-confirmed adult patients with long QT syndrome (LQTS), 2) to study life-threatening cardiac events as a specific end point in adults, and 3) to examine the protective effect of beta-blocker therapy on cardiac events in adult LQTS patients with known cardiac channel mutations.

Background: The clinical course and risk factors for cardiac events in genotype-confirmed adult patients with LQTS have not been previously investigated.

Methods: The clinical characteristics of 812 mutation-confirmed LQTS patients age 18 years or older were studied with both univariate and multivariate analyses to determine the genotype-phenotype factors that influence the clinical course of adult patients with this disorder.

Risk of aborted cardiac arrest or sudden cardiac death during adolescence in the long-QT syndrome.

Context: Analysis of predictors of cardiac events in hereditary long-QT syndrome (LQTS) has primarily considered syncope as the predominant end point. Risk factors specific for aborted cardiac arrest and sudden cardiac death have not been investigated.

Objective: To identify risk factors associated with aborted cardiac arrest and sudden cardiac death during adolescence in patients with clinically suspected LQTS.

[Evaluation of the effects of occupational noxae on the cardiovascular system].

Background: Working conditions and the environment may contribute to the multi-factorial aetiology of cardiovascular disease.

Objectives: To provide a critical assessment of epidemiological and clinical methods and tools for evaluating the effects of occupational pathogenic noxae on the cardiovascular system.

Methods: A review was made of epidemiological and clinical studies published in the main scientific journals of occupational medicine and cardiology, in the period 1980-2003.

Modulating effects of age and gender on the clinical course of long QT syndrome by genotype.

Objectives: We aimed to determine whether long QT syndrome (LQTS) genotype has a differential effect on clinical course of disease in male and female children and adults after adjustment for QTc duration.

Background: Genotype influences clinical course of the LQTS; however, data on the effect of age and gender on this association are limited.

Methods: The LQTS genotype, QTc duration, and follow-up were determined in 243 cases of LQTS caused by the KCNQ1 potassium channel gene mutations (LQT1), 209 cases of LQTS caused by the HERG potassium channel gene mutations (LQT2), and 81 cases of LQTS caused by the SCN5A sodium channel gene mutation (LQT3) gene carriers.

Effects of acute myocardial ischemia on QT dispersion by dipyridamole stress echocardiography.

Increased dispersion of the QT interval has been observed during pacing or exercise stress testing in patients with coronary artery disease (CAD). It has not been established whether this phenomenon is a consequence of ischemia. Therefore, we sought to evaluate whether dipyridamole-induced myocardial ischemia, as directly detected by echocardiographic monitoring of regional contractile function, would affect QT dispersion.