The Short QT Syndrome Proposed Diagnostic Criteria

Inherited Arrhythmia Clinic and Arrhythmia Research Laboratory, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
Journal of the American College of Cardiology (Impact Factor: 16.5). 02/2011; 57(7):802-12. DOI: 10.1016/j.jacc.2010.09.048
Source: PubMed


We aimed to develop diagnostic criteria for the short QT syndrome (SQTS) to facilitate clinical evaluation of suspected cases.
The SQTS is a cardiac channelopathy associated with atrial fibrillation and sudden cardiac death. Ten years after its original description, a consensus regarding an appropriate QT interval cutoff and specific diagnostic criteria have yet to be established.
The MEDLINE database was searched for all reported cases of SQTS in the English language, and all relevant data were extracted. The distribution of QT intervals and electrocardiographic (ECG) features in affected cases were analyzed and compared to data derived from ECG analysis from general population studies.
A total of 61 reported cases of SQTS were identified. Index events, including sudden cardiac death, aborted cardiac arrest, syncope, and/or atrial fibrillation occurred in 35 of 61 (57.4%) cases. The cohort was predominantly male (75.4%) and had a mean QT(c) value of 306.7 ms with values ranging from 248 to 381 ms in symptomatic cases. In reference to the ECG characteristics of the general population, and in consideration of clinical presentation, family history, and genetic findings, a highly sensitive diagnostic scoring system was developed.
Based on a comprehensive review of 61 reported cases of the SQTS, formal diagnostic criteria have been proposed that will facilitate diagnostic evaluation in suspected cases of SQTS. Diagnostic criteria may lead to a greater recognition of this condition and provoke screening of at-risk family members.

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Available from: Jason D Roberts, Nov 24, 2014
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    • "All individuals who participated in the study gave written informed consent prior to genetic and clinical investigations in accordance with the standards of the Declaration of Helsinki and the local ethics committees at each participating institution . To further characterize the genotype-specific characteristics, we created an additional cohort, which consisted of 132 SQTS patients including five families (10 cases) from the current study, 33 families (61 cases) from a review by Gollob et al. [8], and an additional 36 SQTS families (61 cases) that have been previously reported and available on PubMed as of May 2014 [6–9,12–19] (Supplemental Table S1). A full description of the methods is available as supplementary information. "
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    ABSTRACT: Background: Short QT syndrome (SQTS) is a rare inheritable arrhythmia, associated with atrial and ventricular fibrillations, caused by mutations in six cardiac ion channel genes with high penetrance. However, genotype-specific clinical differences between SQTS patients remain to be elucidated. Methods and results: We screened five unrelated Japanese SQTS families, and identified three mutations in KCNH2 and KCNQ1. A novel mutation KCNH2-I560T, when expressed in COS-7 cells, showed a 2.5-fold increase in peak current density, and a positive shift (+14 mV) of the inactivation curve compared with wild type. Computer simulations recapitulated the action potential shortening and created an arrhythmogenic substrate for ventricular fibrillation. In another family carrying the mutation KCNQ1-V141M, affected members showed earlier onset of manifestation and frequent complications of bradyarrhythmia. To determine genotype-specific phenotypes in SQT1 (KCNH2), SQT2 (KCNQ1), and other subtypes SQT3-6, we analyzed clinical variables in 65 mutation-positive patients among all the 132 SQTS cases previously reported. The age of manifestation was significantly later in SQT1 (SQT1: 35 ± 19 years, n = 30; SQT2: 17 ± 25 years, n = 8, SQT3-6: 19 ± 15 years, n = 15; p = 0.011). SQT2 exhibited a higher prevalence of bradyarrhythmia (SQT2: 6/8, 75%; non-SQT2: 5/57, 9%; p < 0.001) and atrial fibrillation (SQT2: 5/8, 63%; non-SQT2: 12/57, 21%; p = 0.012). Of 51 mutation-positive individuals from 16 SQTS families, nine did not manifest short QT, but exhibited other ECG abnormalities such as atrial fibrillation. The resulting penetrance, 82%, was lower than previously recognized. Conclusion: We propose that SQTS patients may exhibit different clinical manifestations depending upon their genotype.
    Full-text · Article · Jul 2015 · International journal of cardiology
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    • "In 2011 Gollob et all defined the clinical criteria for the diagnosis of SQTS. The authors considered 61 patients and made a score using data from these patients (Table 3)[16]. There is not a widely accepted cut-off for QTc, but generally these patients present a QT interval shorter than 320 ms. "
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    ABSTRACT: The advanced knowledge about genetic diseases and their mutations has widened the possibility to have a more precise and definitive diagnosis in many patients, but the use of genetic testing is still controversial. Actually, many cardiomyopathies show the availability of genetic testing. The clinical utility of this testing has been widely debated, but it is evident that the use of genetics must be put in a more organic diagnostic pathway that includes the evaluation of risks and benefits for the patient and his relatives, as well as the costs of the procedure. This review aims to clarify the role of genetic in clinics regarding Channelopaties, less frequent but equally important than other Cardiomyopathies because patients can often be asymptomatic until the first fatal manifestation.
    Full-text · Article · Nov 2013
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    • "The short QT syndrome (SQTS) was first recognized as a distinct clinical entity in 2000 (Gussak et al., 2000). It is characterized by an abnormally short QT interval on the ECG with a QTC interval of ~320 ms or less, tall and peaked T-waves, and increased Tpeak − Tend width (Anttonen et al., 2009; Patel and Pavri, 2009; Couderc and Lopes, 2010; Cross et al., 2011; Gollob et al., 2011). Patients usually have structurally normal hearts and affected families tend to exhibit histories of syncope, abbreviated atrial and ventricular refractory periods, as well as increased susceptibility to atrial and ventricular arrhythmias and sudden death (Gaita et al., 2003; Schimpf et al., 2005; Giustetto et al., 2006; Hancox et al., 2011). "
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    ABSTRACT: Introduction: Genetic forms of the Short QT Syndrome (SQTS) arise due to cardiac ion channel mutations leading to accelerated ventricular repolarization, arrhythmias and sudden cardiac death. Results from experimental and simulation studies suggest that changes to refractoriness and tissue vulnerability produce a substrate favorable to re-entry. Potential electromechanical consequences of the SQTS are less well-understood. The aim of this study was to utilize electromechanically coupled human ventricle models to explore electromechanical consequences of the SQTS. Methods and Results: The Rice et al. mechanical model was coupled to the ten Tusscher et al. ventricular cell model. Previously validated K+ channel formulations for SQT variants 1 and 3 were incorporated. Functional effects of the SQTS mutations on [Ca2+]i transients, sarcomere length shortening and contractile force at the single cell level were evaluated with and without the consideration of stretch-activated channel current (Isac). Without Isac, at a stimulation frequency of 1Hz, the SQTS mutations produced dramatic reductions in the amplitude of [Ca2+]i transients, sarcomere length shortening and contractile force. When Isac was incorporated, there was a considerable attenuation of the effects of SQTS-associated action potential shortening on Ca2+ transients, sarcomere shortening and contractile force. Single cell models were then incorporated into 3D human ventricular tissue models. The timing of maximum deformation was delayed in the SQTS setting compared to control. Conclusion: The incorporation of Isac appears to be an important consideration in modeling functional effects of SQT 1 and 3 mutations on cardiac electro-mechanical coupling. Whilst there is little evidence of profoundly impaired cardiac contractile function in SQTS patients, our 3D simulations correlate qualitatively with reported evidence for dissociation between ventricular repolarization and the end of mechanical systole.
    Full-text · Article · Jul 2013 · Frontiers in Physiology
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