{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,24]],"date-time":"2025-10-24T08:27:15Z","timestamp":1761294435818,"version":"3.37.3"},"reference-count":40,"publisher":"BMJ","issue":"2","license":[{"start":{"date-parts":[[2022,2,9]],"date-time":"2022-02-09T00:00:00Z","timestamp":1644364800000},"content-version":"unspecified","delay-in-days":8,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"published-print":{"date-parts":[[2022,2]]},"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>To evaluate the extent of hydroxychloroquine-induced corrected QT (QTc) prolongation and its relation to COVID-19 infection severity and incidence of polymorphic ventricular arrhythmias and sudden arrhythmic deaths.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>A large-scale cohort study with retrospective analysis of baseline and on-therapy QT interval corrected using Bazett and Fridericia formulas.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>A multicentre study involving eight secondary and tertiary care hospitals of the Abu Dhabi Health Services Company (SEHA), United Arab Emirates.<\/jats:p><\/jats:sec><jats:sec><jats:title>Participants<\/jats:title><jats:p>2014 patients consecutively admitted with PCR-confirmed SARS-CoV-2 infection between 1 March 2020 and 1 June 2020.<\/jats:p><\/jats:sec><jats:sec><jats:title>Interventions<\/jats:title><jats:p>Treatment with hydroxychloroquine alone or in combination with azithromycin for at least 24 hours and with a baseline ECG and at least one ECG after 24 hours of therapy.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main outcome measures<\/jats:title><jats:p>Maximal QTc interval prolongation and its relationship to clinical severity, polymorphic ventricular tachycardia and sudden arrhythmic death while on treatment.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The baseline QTc<jats:sub>(Bazett)<\/jats:sub> was 427.6\u00b125.4 ms and the maximum QTc<jats:sub>(Bazett)<\/jats:sub> during treatment was 439.2\u00b130.4 ms (p&lt;0.001). Severe QTc prolongation (QTc \u2265500 ms) was observed in 1.7%\u20133.3% of patients (Fridericia and Bazett, respectively). There were no cases of polymorphic ventricular arrhythmia or hydroxychloroquine-related arrhythmic death. QTc prolongation was more pronounced in combination therapy compared with hydroxychloroquine alone (22.2 ms vs 11.0 ms, p&lt;0.001) and in patients with higher COVID-19 clinical severity (asymptomatic: 428.4\u00b125.4 ms, severe COVID-19 infection: 452.7\u00b135.7 ms, p&lt;0.001). The overall in-hospital mortality was 3.97% and deceased patients had longer on-therapy QTc<jats:sub>(Bazett)<\/jats:sub> than survivors (459.8\u00b121.4 ms vs 438.4\u00b129.9 ms, p&lt;0.001).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>The incidence of severe QTc prolongation with hydroxychloroquine was low and not associated with ventricular arrhythmia. The safety concerns surrounding the use of hydroxychloroquine may have been overestimated; however, caution should be exercised when using hydroxychloroquine in patients with risk factors for QT prolongation.<\/jats:p><\/jats:sec>","DOI":"10.1136\/bmjopen-2021-051579","type":"journal-article","created":{"date-parts":[[2022,2,9]],"date-time":"2022-02-09T16:39:00Z","timestamp":1644424740000},"page":"e051579","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":3,"title":["Changes in QTc interval after hydroxychloroquine therapy in patients with COVID-19 infection: a large, retrospective, multicentre cohort study"],"prefix":"10.1136","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3761-5546","authenticated-orcid":false,"given":"Moutaz","family":"El Kadri","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Omar","family":"Al Falasi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rizwan","family":"Ahmed","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahlam","family":"Al Awadhi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zainab","family":"Altaha","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amany","family":"Hillis","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Basheer","family":"Panikkaveetil","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sara","family":"Abdalla","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Honey","family":"Ansel Benette","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Adhba","family":"Almubarak","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohammed","family":"Saifuddin","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yousef","family":"Alattar","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5330-904X","authenticated-orcid":false,"given":"Abderrahim","family":"Oulhaj","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Salem","family":"AlKaabi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2022,2,9]]},"reference":[{"doi-asserted-by":"publisher","key":"2022020908352250000_12.2.e051579.1","DOI":"10.1126\/science.abb9332"},{"doi-asserted-by":"publisher","key":"2022020908352250000_12.2.e051579.2","DOI":"10.3389\/fimmu.2018.00302"},{"doi-asserted-by":"publisher","key":"2022020908352250000_12.2.e051579.3","DOI":"10.1093\/cid\/ciaa237"},{"key":"2022020908352250000_12.2.e051579.4","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1038\/s41421-020-0156-0","article-title":"Hydroxychloroquine, a less toxic derivative of chloroquine, is effective in inhibiting SARS-CoV-2 infection in vitro","volume":"6","author":"Liu","year":"2020","journal-title":"Cell Discov"},{"doi-asserted-by":"crossref","unstructured":"Gautret P , Lagier J-C , Parola P , et al . 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