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Does corrected QT interval correlate with serum ionised calcium in the ED setting?
  1. Maroan Cherkaoui1,
  2. Annmarie Touborg Lassen2,3,
  3. Mikkel Brabrand2,3,
  4. Helene Kildegaard4,
  5. Jakob Lundager Forberg1,5
  1. 1 Departmenf of Emergency Medicine, Helsingborg Hospital, Helsingborg, Sweden
  2. 2 Institute of Clinical Medicine, University of Southern Denmark, Odense, Denmark
  3. 3 Department of Emergency Medicine, Odense University Hospital, Odense, Denmark
  4. 4 Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern Denmark, Odense, Denmark
  5. 5 Department of Clinical Sciences, Lund University, Lund, Sweden
  1. Correspondence to Dr Maroan Cherkaoui, Emergency Medicine Department, Helsingborg Hospital, Region Skåne Hälso- och sjukvård, Helsingborg, Sweden; maroan.cherkaoui{at}

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The main ECG changes caused by calcium (Ca) abnormalities have been classified as HR corrected QT interval (QTc) prolongation (hypocalcaemia) and shortening (hypercalcaemia).1 Hypocalcaemia and hypercalcaemia are considered potentially life-threatening conditions, partly because of the theoretical risk of arrhythmia. An experimental study with healthy individuals suggested a relationship between serum ionised calcium (Ca2+) and QTc.2 Only smaller and older clinical studies have, however, tested the correlation of QTc and Ca in patients3–6 and more often using serum total Ca rather than ionised Ca.2 3 5 Although the evidence basis for Ca2+ and its effects on the ECG are weak and their value clinically questionable, the evidence has been adopted into medical literature and clinical practice.1 Furthermore, no evidence is available pertaining to the relationship between Ca2+ and QTc in the diverse ED population. The aim of our study was to investigate whether this relationship exists in the ED and more importantly if it could be useful clinically.

This was an observational study including two Swedish EDs, one in Skåne University Hospital and another in Helsingborg Hospital. We included all adult (≥18 years of age) patients at their first presentation to the EDs from 1 January 2010 …

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  • Handling editor Kirsty Challen

  • Twitter @hckildegaard

  • Contributors MC conceived and designed the study, analysed and interpreted the data, and wrote the report. ATL, MB, HK and JLF conceived and designed the study and assisted with analysis, interpretation of the data and writing of the report. All authors have had access to the data and approved the final version of the manuscript. AS, medical statistician, assisted with the design and interpretation of the statistical analysis. AP, professor of clinical pharmacology, helped review the finished article.

  • Funding The study was funded by independent grants from The Thelma Zoéga Fund for Medical Research, the Research Foundation of Odense University Hospital, The Swedish HeartLung Foundation and Region Skåne. This study was also a part of the Artificially Intelligent use of Registers at Lund University research environment and received funding from the Swedish Research Council (VR, grant number 2019-00198). None of these foundations had any role in the conception, design or conduct of the study; management, analysis or interpretation of the data; or the preparation, review or approval of the manuscript.

  • Competing interests MC, JLF, AL and MB have nothing to declare. HK owns stocks in HL A/S.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.