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PEDIATRICS Vol. 109 No. 5 May 2002, pp. 985

Diagnostic Accuracy of Screening Electrocardiograms in the Long QT Syndrome

To the Editor—

While I agree that the computer diagnostic interpretation offered by the electrocardiograms is often in error, I have found that the measurement offered by most electrocardiograms is quite accurate. In fact, Fig 2 in the article by Miller et al¹ shows an excellent correlation between the computer and manual calculations.

The authors do not offer enough evidence to support their conclusion that all QT intervals should be measured manually. The computerized measurements of QRS and QT durations and axes are sufficiently accurate and a real time-saver.

L. Jerome Krovetz, MD, PhD
Pediatric Cardiology
Boca Raton, FL 33486, USA

REFERENCE

1. Miller MD, Porter CJ, Ackerman MJ. Diagnostic accuracy of screening electrocardiograms in long QT syndrome I. Pediatrics.2001; 108 :8 –12[Abstract/Free Full Text]

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In Reply—

Dr Krovetz suggests that our study failed to provide enough evidence to support our recommendation for independent confirmation and manual calculation of the corrected QT interval. Instead, Dr Krovetz believes that the automated, computerized determination of the QT interval is "sufficiently accurate and a real time-saver." Our study consisted of only a single large family with genotyped long QT syndrome subtype 1. ¹ However, this family posed to the screening electrocardiogram a best-case scenario having pristine T wave inscriptions. Here, as Dr Krovetz indicates, the computer QTc and manual QTc were nearly identical. Moreover, each family member affected with long QT syndrome had a QTc 460 ms. Despite this excellent correlation in calculated QTc, the automated ECG diagnostic interpretation was rendered "normal ECG" for half of the subjects with genotyped long QT syndrome. In addition, our Long QT Syndrome Clinic has encountered numerous ECGs with gross QTc miscalculations. For long QT syndrome, unexplained syncope, or aborted sudden death evaluations, we continue to recommend independent physician overreading of the computer’s QTc calculation and its interpretation relative to the QT interval. Such vigilance is easy to perform, prudent, and potentially life saving. Though the computer determination is a "real time-saver," we have been taught tragically the hard way that it is not "sufficiently accurate."

Michael J Ackerman, MD, PhD
Departments of Medicine, Pediatrics, and Molecular Pharmacology
Long QT Syndrome Clinic
Mayo Clinic/Mayo Foundation
Rochester, MN, USA

Co-burn J Porter, MD
Department of Pediatrics
Pediatric Cardiac Electrophysiology
Mayo Clinic/Mayo Foundation
Rochester, MN, USA

REFERENCE

1. Miller MS, Porter CJ, Ackerman MJ. Diagnostic accuracy of screening electrocardiograms in long QT syndrome I. Pediatrics.2001; 108 :8 –12

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PEDIATRICS (ISSN 1098-4275). ©2002 by the American Academy of Pediatrics

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This Article Extract Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services E-mail this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to My File Cabinet Download to citation manager Request Permissions Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Krovetz, L. J. Articles by Porter, C.-b. J Search for Related Content PubMed PubMed Citation Articles by Krovetz, L. J. Articles by Porter, C.-b. J Social Bookmarking                         What's this?