Measurement and Management of QT Interval Prolongation for General Physicians

Indraratna, Praveen; Tardo, D.; Delves, Madeline; Szirt, Richard; Ng, Brenda

doi:10.1007/s11606-019-05477-7

Cited by 28 publications

(29 citation statements)

References 50 publications

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“…This repolarization prolongation can result in triggered activity by promoting the genesis of early afterdepolarizations and is often spatially heterogeneous, providing a substrate for conduction block and reentrant arrhythmias. Various cardiovascular and non-cardiovascular drugs can also cause relevant QT prolongation, also [8] . This increase in QT time, in turn, is associated with an increased risk of arrhythmia.…”

Section: Arrhythmogenic Risk In the Setting Of Qt-interval Prolongatimentioning

confidence: 99%

QTc evaluation in patients with bundle branch block

Bogossian

Linz

Heijman

et al. 2020

IJC Heart & Vasculature

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Proper measurement of the QT interval on the 12-lead body-surface ECG is challenging in daily practice. Even more difficult is its correct estimation in the presence of repolarization abnormalities, arrhythmias or bundle-branch blocks (BBB). The QT interval results from two parts of the ECG: (1) the QRS complex, describing the excitation of the ventricles and (2) the JT interval, describing the repolarisation of the ventricles. Prolongation of the QRS width – like in the presence of BBB – entails prolongation of the QT interval, making the estimation of the true repolarisation time challenging. The US recommendations for the standardization and interpretation of the ECG suggest focusing on the JT interval in presence of BBB. However, in clinical practice physicians have become more familiar with the interpretation of QT-interval measurements than with the interpretation of the JT Interval. In the last decade, a simple formula for the estimation of the “modified QT interval” in the presence of left or right BBB has been developed and evaluated. In this formula, the modified QT interval is calculated by subtracting 50% of the length of the BBB-QRS from the measured QT interval (QT m = QT BBB − 50% QRS BBB ). Subsequently, rate-correction formula should be applied as usual. In this review, we discuss the determination of the QT-interval in the presence of BBB and summarize the origin and application of the modified QT-interval formula.

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Section: Arrhythmogenic Risk In the Setting Of Qt-interval Prolongatimentioning

confidence: 99%

QTc evaluation in patients with bundle branch block

Bogossian

Linz

Heijman

et al. 2020

IJC Heart & Vasculature

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“…This is despite specific recommendations for correct measurement of QT c interval. 2,[24][25][26] Other research also shows variability in human QT c measurements. 27 It may be beneficial to standardize QT c interval measurement process using technological solutions.…”

Section: Discussionmentioning

confidence: 94%

Community pharmacist use of mobile ECG to inform drug therapy decision making for patients receiving QTc prolonging medications

Witry

Oelmann²,

Frerichs³

et al. 2021

J Am Coll Clin Pharm

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IntroductionFor patients using QTc prolonging medications, the health care system is challenged to mitigate the risk of drug‐induced long‐QT syndrome (DiLQTS) and sudden cardiac death (SCD). Community pharmacists (CPs) receive QTc alerts when dispensing but intervene infrequently. Personal electrocardiogram (ECG) monitors are a new, inexpensive technology that could provide additional patient risk information to identify individuals with a prolonged QTc interval in real time.Objectives(1) Describe QTc interval‐prolonging medications, QTc interval calculations, and associated interventions and prescriber responses for a CP‐delivered QTc interval assessment program, and (2) Describe patient satisfaction with the service.MethodsA prospective study of 9‐month duration in three community pharmacies in Iowa. CPs were trained to measure QTc interval using the KardiaMobile ECG monitor. English‐speaking patients aged ≥18 years were recruited to have a 30 seconds ECG tracing if the CP received a computer QTc‐related alert or had concern about QTc effect/interaction. CPs used professional judgment regarding prescriber contact but were required to contact the prescriber if the QTc interval was prolonged (>470 ms males, >480 ms females).ResultsThere were 53 patients who met study criteria and participated in the service. Mean age was 55.1 years, 38 (72%) were female, and 19 (36%) received newly prescribed QTc interval‐prolonging medications. A computer‐generated QTc alert was present for 36 (68%) of participants. CPs contacted a prescriber for 6 (11%) patients regarding concern for DiLQTS (mean QTc 495 ms). Of these six instances, three had QTc prolongation requiring mandatory prescriber contact (mean QTc 529 ms). Prescriber contact resulted in medication changes for 3 (50%) patients.ConclusionCPs were able to measure QTc interval, identify patients at risk for DiLQTS, and make accepted medication therapy recommendations related to QTc prolongation. CP assessment of QTc interval may be a useful approach to improve risk stratification of individuals at risk of DiLQTS and SCD.Trial registration: Clinical Trials.gov Identifier: NCT04000542.

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“…Praktikabel ist die Empfehlung "Ableitungen mit sehr flacher QT-Zeit nur mit Vorsicht zu interpretieren", und solche, wo "die T-Welle klar definiert ist", zu bevorzugen. Nichtsdestotrotz gilt es, die längste QT-Zeit zu identifizieren [7].…”

Section: Spotlight: Wie Bestimmt Man Das Qtc-intervall Richtig?unclassified

“…Es existieren verschiedene Formeln für die Frequenzkorrektur [7]. Dabei gilt für alle Formeln, dass bei extremer Bradykardie oder Tachykardie die Zuverlässigkeit abnimmt.…”

Section: Einfluss Der Herzfrequenz Auf Die Qtc-zeitunclassified

“…Dabei gilt für alle Formeln, dass bei extremer Bradykardie oder Tachykardie die Zuverlässigkeit abnimmt. Die am häufigsten benutzte "Bazett"-Formel hat sich als ausreichend zuverlässig im Kommt es zu Tachykardien, so sind die komplexeren Formeln "Framingham" und "Hodges" zu bevorzugen [7]: Insbesondere beim Vorliegen von QRS-Verbreiterungen im Sinne von Schenkelblockierungen hat sich bei höheren Frequenzen die Hodges-Formel als zuverlässiger erwiesen [9]. Wegen der Komplexität der Formeln ist die Kalkulation durch einen QTc-Rechner zu empfehlen.…”

Section: Einfluss Der Herzfrequenz Auf Die Qtc-zeitunclassified

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Spotlight: Wie bestimmt man das QTc-Intervall richtig?

Bogossian¹,

Bimpong-Buta²,

Lemke

2020

Aktuelle Kardiologie

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ZusammenfassungDas EKG stellt eine der wichtigsten nicht invasiven Untersuchungsmethoden dar. Im klinischen Alltag bietet es einen hohen Informationsgehalt bei sehr geringen Kosten. Nichtsdestotrotz ist die EKG-Interpretation für viele Ärzte herausfordernd. Selbst bei einem normalen EKG bedarf es ausreichender Sorgfalt, um die einzelnen Zeitintervalle ordentlich zu vermessen. Deutlich schwieriger wird die Interpretation beim Auftreten von Herzrhythmusstörungen. Hier müssen dann (wie z. B. beim Vorhofflimmern) mehrere Messungen durchgeführt und berücksichtigt werden, um das QT-Intervall korrekt zu beurteilen. Weitere EKG-Veränderungen können die Messung und Interpretation der QT-Zeit weiter beeinflussen. So kommt insbesondere bei Frequenzvariabilität (Tachykardien/Bradykardien) und beim Auftreten von Schenkelblockierungen die Anwendung diverser Formeln zum Tragen. Erst nach Berücksichtigung all dieser Aspekte kann eine ordentliche Messung und Interpretation der QTc-Zeit erfolgen.

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Measurement and Management of QT Interval Prolongation for General Physicians

Cited by 28 publications

References 50 publications

QTc evaluation in patients with bundle branch block

QTc evaluation in patients with bundle branch block

Community pharmacist use of mobile ECG to inform drug therapy decision making for patients receiving QTc prolonging medications

Spotlight: Wie bestimmt man das QTc-Intervall richtig?

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