Diagnostic criteria for the long QT syndrome. An update.

Schwartz, Peter J.; Moss, Arthur J.; Vincent, G; Crampton, Richard S.

doi:10.1161/01.cir.88.2.782

Cited by 1,018 publications

(561 citation statements)

References 26 publications

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“…Although there are a number of methods available to correct the QT interval for heart rate (i.e. calculate QTc), Bazett's correction (QT divided by the square root of the RR interval) remains the standard [12,13], and during sinus rhythm a QTc of >440 ms is considered prolonged [15]. In normal subjects, QTc varies with age and is longer in females than males after the onset of puberty [17], possibly due to gradual QT shortening in males [18].…”

Section: Discussionmentioning

confidence: 99%

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Prolonged cardiac repolarisation during spontaneous nocturnal hypoglycaemia in children and adolescents with type 1 diabetes

et al. 2004

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Aims/hypothesis. It has been postulated that hypoglycaemia-related cardiac dysrhythmia and, in particular, prolonged cardiac repolarisation, may contribute to increased mortality rates in children and adolescents with type 1 diabetes. Methods. We examined the prevalence of prolonged QT interval on ECG during spontaneous hypoglycaemia in 44 type 1 diabetic subjects (aged 7-18 years), and explored the relationships between serial overnight measurements of QT interval corrected for heart rate (QTc) and serum glucose, potassium and epinephrine levels. Each subject underwent two overnight profiles; blood was sampled every 15 min for glucose measurements and hourly for potassium and epinephrine. Serial ECGs recorded half-hourly between 23.00 and 07.00 hours were available on 74 nights: 29 with spontaneous hypoglycaemia (defined as blood glucose <3.5 mmol/l) and 45 without hypoglycaemia.Results. Mean overnight QTc was longer in females than in males (412 vs 400 ms, p=0.02), but was not related to age, diabetes duration or HbA 1 c. Prolonged QTc (>440 ms) occurred on 20 out of 74 (27%) nights, with no significant differences between male and female subjects, and was more prevalent on nights with hypoglycaemia (13/29, 44%) than on nights without (7/45, 15%, p=0.0008). Potassium levels were lower on nights when hypoglycaemia occurred (minimum potassium 3.4 vs 3.7 mmol/l, p=0.0003) and were inversely correlated with maximum QTc (r=−0.40, p=0.03). In contrast, epinephrine levels were not higher on nights with hypoglycaemia and were not related to QTc. Conclusions/interpretation. In young type 1 diabetic subjects, prolonged QTc occurred frequently with spontaneous overnight hypoglycaemia and may be related to insulin-induced hypokalaemia.

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Section: Discussionmentioning

confidence: 99%

“…QT interval was measured from the beginning of the Q wave to the end of the T wave using the intersection of the T wave with the isoelectric line [11]. The QT intervals were corrected for heart rate using Bazett's formula to generate QTc values [12,13]. Assays.…”

Section: Overnight Metabolic Profiles and Ecg Monitoringmentioning

confidence: 99%

Prolonged cardiac repolarisation during spontaneous nocturnal hypoglycaemia in children and adolescents with type 1 diabetes

et al. 2004

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“…The LQTS risk score (Schwartz) was based on QTc from ECG 2 because it was least affected by environmental factors 2, 10. The difference in QTc between ECG 1 and ECG 2 was also calculated.…”

Section: Methodsmentioning

confidence: 99%

“…An LQTS risk score (Schwartz) >3 is also considered diagnostic 2, 7, 10. In accordance with current clinical guidelines for LQTS, genetic analyses have often been limited to the 3 main LQTS genes.…”

Section: Introductionmentioning

confidence: 99%

Genetic and Phenotypic Characterization of Community Hospital Patients With QT Prolongation

Gibbs

Thalamus

Tveten

et al. 2018

JAHA

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BackgroundCongenital long‐QT syndrome (LQTS) is a genetic disorder characterized by prolongation of the corrected QT interval (QTc) on an ECG. The aim of the present study was to estimate the prevalence of pathogenic and likely pathogenic sequence variants in patients who had at least 1 ECG with a QTc ≥500 ms.Methods and ResultsTelemark Hospital Trust is a community hospital within the Norwegian national health system, serving ≈173 000 inhabitants. We searched the ECG database at Telemark Hospital Trust, Norway, from January 2004 to December 2014, and identified 1531 patients with at least 1 ECG with a QTc ≥500 ms. At the time of inclusion in this study (2015), 766 patients were alive. A total of 733 patients were invited to participate, and 475 accepted. The 17 genes that have been reported to cause monogenic LQTS were sequenced among the patients. Pro‐QTc score was calculated for each patient. A molecular genetic cause of LQTS was detected in 31 (6.5%) of 475 patients. These patients had a lower pro‐QTc score than those without pathogenic or likely pathogenic variants (1.7±1.0 versus 2.8±1.6; P<0.001).ConclusionsCompared with the general population, hospitalized patients with a QTc ≥500 ms in at least 1 ECG recording had an increased likelihood for pathogenic and likely pathogenic variants in LQTS genes. We recommend increased awareness of the possibility of LQTS in patients with at least 1 ECG with a QTc ≥500 ms.

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“…Examples of these conditions are vagotonia, sleeping, advanced age, myocardial ischemia, post-arrhythmia, resuscitation after heart arrest, central nervous system diseases, use of anti-arrhythmic drugs, electrolytic changes, congenital long QT syndrome, and use of psychotropic drugs (1)(2)(3)(4). Some include predisposition to severe and even lethal ventricular arrhythmia (5).…”

Section: Introductionmentioning

confidence: 99%

An analysis of the electrocardiogram QT interval

Koehler

Zouvi

Acevedo

et al. 2004

Braz J Med Biol Res

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No reports testing the efficacy of the use of the QT/RR ratio <1/2 for detecting a normal QTc interval were found in the literature. The objective of the present study was to determine if a QT/RR ratio ≤1/2 can be considered to be equal to the normal QTc and to compare the QT and QTc measured and calculated clinically and by a computerized electrocardiograph. Ratios (140 QT/RR) of 28 successive electrocardiograms obtained from 28 consecutive patients in a tertiary level teaching hospital were analyzed clinically by 5 independent observers and by a computerized electrocardiograph. The QT/RR ratio provided 56% sensitivity and 78% specificity, with an area under the receiver operator characteristic curve of 75.8% (95%CI: 0.68 to 0.84). The divergence in QT and QTc interval measurements between clinical and computerized evaluation were 0.01 ± 0.03 s (95%CI: 0.04-0.02) and 0.01 ± 0.04 s (95%CI: -0.05-0.03), respectively. The QT and QTc values measured clinically and by a computerized electrocardiograph were similar. The QT/RR ratio ≤1/2 was not a satisfactory index for QTc evaluation because it could not predict a normal QTc value.

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Diagnostic criteria for the long QT syndrome. An update.

Cited by 1,018 publications

References 26 publications

Prolonged cardiac repolarisation during spontaneous nocturnal hypoglycaemia in children and adolescents with type 1 diabetes

Prolonged cardiac repolarisation during spontaneous nocturnal hypoglycaemia in children and adolescents with type 1 diabetes

Genetic and Phenotypic Characterization of Community Hospital Patients With QT Prolongation

An analysis of the electrocardiogram QT interval

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