LQTS Patients (LQT + patient)

Distribution by Scientific Domains


Selected Abstracts


The Risk of Cardiac Events and Genotype-Based Management of LQTS Patients

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2009
Ph.D., oskot M.D., yna Markiewicz-
This review discusses the risk of cardiac events and genotype-based management of LQTS. We describe here the genetic background of long QT syndrome and the eleven different genes for ion-channels and a structural anchoring protein associated with that disorder. Clinical Background section discusses the risk of cardiac events associated with different LQTS types. Management and Prevention section describes in turn gene-specific therapy, which was based on the identification of the gene defect and the dysfunction of the associated transmembrane ion channel. In patients affected by LQTS, genetic analysis is useful for risk stratification and for making therapeutic decisions. A recent study reported a quite novel pathogenic mechanism for LQTS and suggested that treatments aimed at scaffolding proteins rather than specific ion channels may be an alternative to antiarrhythmic strategy in the future. [source]


Age- and Genotype-Specific Triggers for Life-Threatening Arrhythmia in the Genotyped Long QT Syndrome

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2008
TOMOKO SAKAGUCHI M.D.
Introduction: Patients with long QT syndrome (LQTS) become symptomatic in adolescence, but some become at age of ,20 years. Since it remains unknown whether clinical features of symptomatic LQTS patients differ depending on the age of onset, we aimed to examine whether triggers for cardiac events are different depending on the age in genotyped and symptomatic LQTS patients. Methods and Results: We identified 145 symptomatic LQTS patients, divided them into three groups according to the age of first onset of symptoms (young <20, intermediate 20,39, and older ,40 years), and analyzed triggers of cardiac events (ventricular tachycardia, syncope, or cardiac arrest). The triggers were divided into three categories: (1) adrenergically mediated triggers: exercise, emotional stress, loud noise, and arousal; (2) vagally mediated triggers: rest/sleep; and (3) secondary triggers: drugs, hypokalemia, and atrioventricular (AV) block. In the young group, 78% of the cardiac events were initiated by adrenergically mediated triggers and 22% were vagally mediated, but none by secondary triggers. In contrast, the adrenergically mediated triggers were significantly lower in the intermediate group. The percentage of secondary triggers was significantly larger in the older group than in the other two groups (0% in young vs 23% in intermediate vs 72% in older; P < 0.0001). Concerning the subdivision of secondary triggers on the basis of genotype, hypokalemia was only observed in LQT1, drugs mainly in LQT2, and AV block only in LQT2. Conclusion: Arrhythmic triggers in LQTS differ depending on the age of the patients, stressing the importance of age-related therapy for genotyped LQTS patients. [source]


Prolonged Atrial Action Potential Durations and Polymorphic Atrial Tachyarrhythmias in Patients with Long QT Syndrome

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2003
PAULUS KIRCHHOF M.D.
Introduction: Prolongation of the QT interval and torsades de pointes tachycardias due to altered expression or function of repolarizing ion channels are the hallmark of congenital long QT syndrome (LQTS). The same ion channels also contribute to atrial repolarization, and familial atrial fibrillation may be associated with a mutated KVLQT1 gene. We therefore assessed atrial action potential characteristics and atrial arrhythmias in LQTS patients. Methods and Results: Monophasic action potentials (MAPs) were simultaneously recorded from the right atrial appendage and the inferolateral right atrium in 10 patients with LQTS (8 with identifiable genotype) and compared to 7 control patients. Atrial arrhythmias also were compared to MAPs recorded in patients with persistent (n = 10) and induced (n = 4) atrial fibrillation. Atrial action potential durations (APD) and effective refractory periods (ERP) were prolonged in LQTS patients at cycle lengths of 300 to 500 msec (APD prolongation 30,41 msec; ERP prolongation 26,52 msec; all P < 0.05). Short episodes of polymorphic atrial tachyarrhythmias (polyAT, duration 4,175 sec) occurred spontaneously or during pauses after pacing in 5 of 10 LQTS patients, but not in controls (P < 0.05). P waves showed undulating axis during polyAT. Cycle lengths of polyAT were longer than during persistent and induced atrial fibrillation. Afterdepolarizations preceded polyAT in 2 patients. The electrical restitution curve was shifted to longer APD in LQTS patients and to even longer APD in LQTS patients with polyAT. Conclusion: This group of LQTS patients has altered atrial electrophysiology: action potentials are prolonged, and polyAT occurs. PolyAT appears to be a specific arrhythmia of LQTS reminiscent of an atrial form of "torsades de pointes."(J Cardiovasc Electrophysiol, Vol. 14, pp ***-***, October 2003) [source]


QT Interval Variability and Adaptation to Heart Rate Changes in Patients with Long QT Syndrome

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2009
JAN N, MEC M.D.
Background: Increased QT variability (QTV) has been reported in conditions associated with ventricular arrhythmias. Data on QTV in patients with congenital long QT syndrome (LQTS) are limited. Methods: Ambulatory electrocardiogram recordings were analyzed in 23 genotyped LQTS patients and in 16 healthy subjects (C). Short-term QTV was compared between C and LQTS. The dependence of QT duration on heart rate was evaluated with three different linear models, based either on the RR interval preceding the QT interval (RR0), the RR interval preceding RR0 (RR -1), or the average RR interval in the 60-second period before QT interval (mRR). Results: Short-term QTV was significantly higher in LQTS than in C subjects (14.94 ± 9.33 vs 7.31 ± 1.29 ms; P < 0.001). It was also higher in the non-LQT1 than in LQT1 patients (23.00 ± 9.05 vs 8.74 ± 1.56 ms; P < 0.001) and correlated positively with QTc in LQTS (r = 0.623, P < 0.002). In the C subjects, the linear model based on mRR predicted QT duration significantly better than models based on RR0 and RR -1. It also provided better fit than any nonlinear model based on RR0. This was also true for LQT1 patients. For non-LQT1 patients, all models provided poor prediction of QT interval. Conclusions: QTV is elevated in LQTS patients and is correlated with QTc in LQTS. Significant differences with respect to QTV exist among different genotypes. QT interval duration is strongly affected by noninstantaneous heart rate in both C and LQT1 subjects. These findings could improve formulas for QT interval correction and provide insight on cellular mechanisms of QT adaptation. [source]


Clinical Value of Electrocardiographic Parameters in Genotyped Individuals with Familial Long QT Syndrome

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2001
GEROLD MOENNIG
MOENNIG, G., et al.: Clinical Value of Electrocardiographic Parameters in Genotyped Individuals with Familial Long QT Syndrome. Rate corrected QT interval (QTc) and QT dispersion (QTd) have been suggested as markers of an increased propensity to arrhythmic events and efficacy of therapy in patients with long QT syndrome (LQTS). To evaluate whether QTc and QTd correlate to genetic status and clinical symptoms in LQTS patients and their relatives, ECGs of 116 genotyped individuals were analyzed. JTc and QTc were longest in symptomatic patients (n = 28). Both QTd and JTd were significantly higher in symptomatic patients than in asymptomatic (n = 29) or unaffected family members (n = 59). The product of QTd/JTd and QTc/JTc was significantly different among all three groups. Both dispersion and product put additional and independent power on identification of mutation carriers when adjusted for sex and age in a logistic regression analysis. Thus, symptomatic patients with LQTS show marked inhomogenity of repolarization in the surface ECG. QT dispersion and QT product might be helpful in finding LQTS mutation carriers and might serve as additional ECG tools to identify asymptomatic LQTS patients. [source]


Long QT Syndrome in African-Americans

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2010
Thomas Fugate II B.S.
Background: We evaluated the risk factors and clinical course of Long QT syndrome (LQTS) in African-American patients. Methods: The study involved 41 African-Americans and 3456 Caucasians with a QTc , 450 ms from the U.S. portion of the International LQTS Registry. Data included information about the medical history and clinical course of the LQTS patients with end points relating to the occurrence of syncope, aborted cardiac arrest, or LQTS-related sudden cardiac death from birth through age 40 years. The statistical analyses involved Kaplan-Meier time to event graphs and Cox regression models for multivariable risk factor evaluation. Results: The QTc was 29 ms longer in African-Americans than Caucasians. Multivarite Cox analyses with adjustment for decade of birth revealed that the cardiac event rate was similar in African-Americans and Caucasians with LQTS and that beta-blockers were equally effective in reducing cardiac events in the two racial groups. Conclusions: The clinical course of LQTS in African-Americans is similar to that of Caucasians with comparable risk factors and benefit from beta-blocker therapy in the two racial groups. Ann Noninvasive Electrocardiol 2010;15(1):73,76 [source]


Assessment of Microvolt T-Wave Alternans in High-Risk Patients with the Congenital Long-QT Syndrome

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2009
Jörn Schmitt M.D.
Background: Microvolt T-wave alternans (MTWA) has been used for arrhythmogenic risk stratification in cardiac disease conditions associated with increased risk of sudden cardiac death. Macroscopic T-wave alternans has been observed in patients with congenital long-QT syndrome (LQTS). The role of MTWA testing in patients with LQTS has not been established. Objective: To determine the diagnostic value of MTWA testing in high-risk patients with LQTS. Methods and results: We assessed MTWA in 10 consecutive LQTS index patients who survived cardiac arrest or had documented torsade de pointes tachycardia and 6 first-degree family members with congenital LQTS which had been genotyped in 13 of 16 subjects (7 index patients, 6 family members). No LQTS-causing mutation was identified in 3 index patients with overt QT prolongation. MTWA was assessed during standardized bicycle exercise testing using the spectral method and yielded negative (n = 8) or indeterminate (n = 2) results in index patients, respectively. Similarly, all first-degree family members tested MTWA negative except for one indeterminate result. Two genotype positive family members could not be tested (two children,4 and 9 years of age). Conclusion: In patients with congenital LQTS, free from structural heart disease and with a history of life-threatening cardiac arrhythmias, assessment of MTWA does not yield diagnostic value. Hence, determination of MTWA in lower risk LQTS patients without spontaneous arrhythmic events is likely not to be useful for arrhythmia risk stratification. [source]


Long QT Syndrome in Patients over 40 Years of Age: Increased Risk for LQTS-Related Cardiac Events in Patients with Coronary Disease

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2008
Edward Sze B.A.
Background: Previous studies of long QT syndrome (LQTS) have focused primarily on the clinical course of affected patients up to 40 years of age to avoid the confounding influence of acquired heart disease on LQTS-related cardiac events in this genetic disorder. Methods: Patients were identified as having coronary disease if they had a history of hospitalization for myocardial infarction, coronary angioplasty, coronary artery bypass graft surgery, or were treated with medication for angina. LQTS-related cardiac events included the first occurrence of syncope, aborted cardiac arrest, or sudden cardiac death without evidence suggestive of an acute coronary event. Cox proportional hazards regression modeling was used to analyze the independent contribution of coronary disease to LQTS-related cardiac events. Results: Time-dependent coronary disease was associated with an increased risk of LQTS-related cardiac events (hazard ratio 2.24, 95% confidence interval 1.23,4.07, P = 0.008) after adjustment for syncopal history before age 40, QTc, and gender. Factors such as diabetes and hypertension that increase the risk for coronary disease were not associated with an increased risk for LQTS-related cardiac events. Conclusions: This is the first study to demonstrate that coronary disease augments the risk for LQTS-related cardiac events in LQTS. The findings highlight the need for more focused preventive therapy in LQTS patients above the age of 40. [source]