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Amiodarone and Ventricular Arrhythmia Suppression
- James R. Cook, MD
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Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
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TO THE EDITOR:
In their interesting report on the “rapid and dramatic” reduction in ventricular arrhythmias in patients treated with oral amiodarone, Kim and colleagues [1] correctly point out the possible confounding effects of other antiarrhythmics administered early in the course of amiodarone loading. Despite this caveat, the graphs and P values presented appear impressive. However, several problems in the analysis may render the conclusion erroneous. First, use of analysis of variance (ANOVA) requires an implicit assumption of normally distributed data. No mention was made of data transformation (that is, logarithms), often used to reduce the influence of extreme values and approximate a normally distributed variance. In subsequent analyses, the authors used the Kruskal-Wallis test, a statistic useful for analysis of non-normally distributed data, but the required comparison with the chi-square distribution to test for significance was not cited [2]. In the absence of this and an F statistic for the ANOVA, the source of the reported P value is unclear. Finally, no attempt appears to have been made to adjust for an acceptable level of significance when multiple comparisons were considered [3].
Previous studies have demonstrated arrhythmia suppression in patients treated with amiodarone [4], but others have shown placebo “therapy” also results in significant arrhythmia suppression when similar efficacy criteria are used [5]. I believe that correct analysis will not support their conclusion.
James R. Cook
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
- Copyright ©2004 by the American College of Physicians
