Manual versus Automatic Assessment of the QT-Interval and QTc

• Published in: Europace (London, England)
• Main Authors: Neumann, Benjamin, Vink, A Suzanne, Hermans, Ben J M, Lieve, Krystien V V, Cömert, Didem, Beckmann, Britt-Maria, Clur, Sally-Ann B, Blom, Nico A, Delhaas, Tammo, Wilde, Arthur A M, Kääb, Stefan, Postema, Pieter G, Sinner, Moritz F
• Format: Journal Article
• Language: English
• Published: England 20.07.2023
• Subjects: QTc; QT-interval; electrocardiogram; Long QT Syndrome; mis-assessment; sudden cardiac death
• ISSN: 1532-2092
• DOI: 10.1093/europace/euad213

Sudden cardiac death (SCD) is challenging to predict. Electrocardiogram (ECG) derived, heart rate corrected QT-interval (QTc) is used for SCD-risk assessment. QTc is preferably determined manually, but vendor-provided automatic results from ECG-recorders are convenient. Agreement between manual and automatic assessments is unclear for populations with aberrant QTc. We aimed to systematically assess pairwise agreement of automatic and manual QT-intervals and QTc. A multi-center cohort enriching aberrant QTc comprised ECGs of healthy controls and Long-QT Syndrome (LQTS) patients. Manual QT-intervals and QTc were determined by the tangent and threshold methods and compared to automatically generated, vendor-provided values. We assessed agreement globally by intra-class correlation coefficients and pairwise by Bland-Altman analyses and 95% limits of agreement (LoA). Further, manual results were compared to a novel automatic QT-interval algorithm. ECGs of 1263 participants (720 LQTS-patients; 543 controls) were available (median age 34 [IQR 35] years, 55% women). Comparing cohort means, automatic and manual QT-intervals and QTc were similar. However, pairwise Bland-Altman-based agreement was highly discrepant. For QT-interval, LoAs spanned 95 ms (tangent) and 92 ms (threshold), respectively. For QTc, the spread was 108 ms and 105 ms, respectively. LQTS-patients exhibited more pronounced differences. For automatic QTc results from 440-540 ms (tangent) and 430-530 ms (threshold), mis-assessment risk was highest. Novel automatic QT-interval algorithms may narrow this range. Pairwise vendor-provided automatic and manual QT-interval and QTc results can be highly discrepant. Novel automatic algorithms may improve agreement. Within the above ranges, automatic QT-interval and QTc results require manual confirmation, particularly if T-wave morphology is challenging.