Comparison of QT Interval Measurement Methods and Correction Formulas in Atrial Fibrillation

Tooley, James E.; Ouyang, David; Hadley, David; Turakhia, Mintu P.; Wang, Paul; Ashley, Euan A.; Froelicher, Victor; Pérez, Marco

doi:10.1016/j.amjcard.2019.02.057

Cited by 24 publications

(26 citation statements)

References 7 publications

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“…9 Averaged QTc for 5 consecutive beats in atrial fibrillation. 11 Adjusted QTc for wide QRS: adjusted QTc = QTc – [QRS-120]. 12 …”

Section: Methodsmentioning

confidence: 99%

The Clinical Utility of Continuous QT Interval Monitoring in Patients Admitted With COVID-19 Compared With Standard of Care: A Prospective Cohort Study

Alqarawi¹,

Birnie²,

Golian³

et al. 2020

CJC Open

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Background QT interval monitoring has gained much interest during the COVID-19 pandemic given the use of QT-prolonging medications and the concern about viral transmission with serial ECGs. We hypothesized that continuous telemetry- based QT monitoring is associated with better detection of prolonged QT episodes. Methods We introduced Continuous Cardiac Telemetry (CCT) with an algorithm for automated QT interval monitoring to our designated COVID-19 units. The daily maximum automated heart-rate corrected QT (Auto-QTc) measurements were recorded. We compared the proportion of marked QTc prolongation episodes (Long-QTc), defined as QTc > 500 ms, in patients with suspected or confirmed COVID-19 who were admitted before and after CCT was implemented (control group vs CCT group, respectively). Manual QTc measurement by electrophysiologists (EP-QTc) was used to verify Auto-QTc. Charts were reviewed to describe the clinical response to Long-QTc episodes. Results We included 33 consecutive patients (total of 451 monitoring days). Long-QTc episodes were detected more frequently in the CCT group [69/206 (34%) vs 26/245 (11%), P < 0.0001] and ECGs were performed less frequently [32/206 (16%) vs 78/245 (32%), P < 0.0001]. Auto-QTc correlated well with EP-QTc with an excellent agreement in detecting Long-QTc (Kappa=0.8, P<0.008). Only 28% of Long-QTc episodes were treated with recommended therapies. There was one episode of Torsade de Pointes (TdP) in the control group and none in the CCT group. Conclusion Continuous QT interval monitoring is superior to standard of care in detecting episodes of Long-QTc with minimal need for ECGs. The clinical response to Long-QTc episodes is suboptimal.

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“…9 Averaged QTc for 5 consecutive beats in atrial fibrillation. 11 Adjusted QTc for wide QRS: adjusted QTc = QTc – [QRS-120]. 12 …”

Section: Methodsmentioning

confidence: 99%

The Clinical Utility of Continuous QT Interval Monitoring in Patients Admitted With COVID-19 Compared With Standard of Care: A Prospective Cohort Study

Alqarawi¹,

Birnie²,

Golian³

et al. 2020

CJC Open

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“…Nichtsdestotrotz sollten diese Werte gegengeprüft werden. Dabei sollte die QT-Zeit an 5 aufeinanderfolgenden Komplexen gemessen und gemittelt werden, um eine bessere Abschätzung des QT-Intervalls zu erzielen [12].…”

Section: Einfluss Von Rhythmusstörungen Auf Die Qtc-zeitunclassified

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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“…When aligning the individual complexes and using sample‐by‐sample voltage medians rather than sample‐by‐sample averages, the process also filters the native recording and creates images that are easier to interpret. This is also true for recordings in which the QT interval measurement in individual beats is problematic because of underlying biological noise (Figure ), such as ECGs of patients with atrial fibrillation (Tooley et al, ) or in Parkinson's disease patients (Malik, Andreas, et al, ). The only exception in which this technology fails is fixed ratio atrial flutter with phase‐locked flutter waves and QRS complexes and with superimposition of flutter waves with the terminal part of the T wave.…”

Section: Electrocardiographic Measurementsmentioning

confidence: 99%

Sources of QTc variability: Implications for effective ECG monitoring in clinical practice

Hnatkova

Malik

2019

Noninvasive Electrocardiol

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Pharmaceuticals that prolong ventricular repolarization may be proarrhythmic in susceptible patients. While this fact is well recognized, schemes for sequential QTc interval monitoring in patients receiving QT‐prolonging drugs are frequently overlooked or, if implemented, underutilized in clinical practice. There are several reasons for this gap in day‐to‐day clinical practice. One of these is the perception that serially measured QTc intervals are subject to substantial variability that hampers the distinction between potential proarrhythmic signs and other sources of QTc variability. This review shows that substantial part of the QTc variability can be avoided if more accurate methodology for electrocardiogram collection, measurement, and interpretation is used. Four aspects of such a methodology are discussed. First, advanced methods for QT interval measurement are proposed including suggestion of multilead measurements in problematic recordings such as those in atrial fibrillation patients. Second, serial comparisons of T‐wave morphologies are advocated instead of simple acceptance of historical QTc measurements. Third, the necessity of understanding the pitfalls of heart rate correction is stressed including the necessity of avoiding the Bazett correction in cases of using QTc values for clinical decisions. Finally, the frequently overlooked problem of QT‐heart rate hysteresis is discussed including the possibility of gross QTc errors when correcting the QT interval for simultaneously measured short‐term heart rate.

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Comparison of QT Interval Measurement Methods and Correction Formulas in Atrial Fibrillation

Cited by 24 publications

References 7 publications

The Clinical Utility of Continuous QT Interval Monitoring in Patients Admitted With COVID-19 Compared With Standard of Care: A Prospective Cohort Study

The Clinical Utility of Continuous QT Interval Monitoring in Patients Admitted With COVID-19 Compared With Standard of Care: A Prospective Cohort Study

Spotlight: Wie bestimmt man das QTc-Intervall richtig?

Sources of QTc variability: Implications for effective ECG monitoring in clinical practice

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