{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T18:42:50Z","timestamp":1780512170976,"version":"3.54.1"},"reference-count":21,"publisher":"BMJ","issue":"2","license":[{"start":{"date-parts":[[2021,9,16]],"date-time":"2021-09-16T00:00:00Z","timestamp":1631750400000},"content-version":"unspecified","delay-in-days":15,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"fondsb\u00f8rsvekselerer Henry Hansen og hustrus legat"},{"DOI":"10.13039\/501100006197","name":"Fonden til L\u00e6gevidenskabens Fremme","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100006197","id-type":"DOI","asserted-by":"publisher"}]},{"name":"the FUKAP foundation"},{"DOI":"10.13039\/501100003554","name":"Lundbeckfonden","doi-asserted-by":"publisher","award":["R358-2020-2343"],"award-info":[{"award-number":["R358-2020-2343"]}],"id":[{"id":"10.13039\/501100003554","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100008214","name":"K\u00f8bmand Sven Hansen og Hustru Ina Hansens Fond","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100008214","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100007405","name":"Hjerteforeningen","doi-asserted-by":"publisher","award":["Grant 17-R115-A7532-22065"],"award-info":[{"award-number":["Grant 17-R115-A7532-22065"]}],"id":[{"id":"10.13039\/100007405","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["Open Heart"],"accepted":{"date-parts":[[2021,8,27]]},"published-print":{"date-parts":[[2021,9]]},"abstract":"<jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>In long QT syndrome (LQTS), beta blockers prevent arrhythmias. As a supplement, means to increase potassium has been suggested. We set to investigate the effect of moderate potassium elevation on cardiac repolarisation.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>Patients with LQTS with a disease-causing <jats:italic>KCNQ1<\/jats:italic> or <jats:italic>KCNH2<\/jats:italic> variant were included. In addition to usual beta-blocker treatment, patients were prescribed (1) 50 mg spironolactone (<jats:italic>low dose<\/jats:italic>) or (2) 100 mg spironolactone and 3 g potassium chloride per day (<jats:italic>high dose+<\/jats:italic>). Electrocardiographic measures were obtained at baseline and after 7 days of treatment.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Twenty patients were enrolled (10 low dose and 10 high dose+). One patient was excluded due to severe influenza-like symptoms, and 5 of 19 patients completing the study had mild side effects. Plasma potassium in low dose did not increase in response to treatment (4.26\u00b10.22 to 4.05\u00b10.19 mmol\/L, p=0.07). Also, no change was observed in resting QTcF (QT interval corrected using Fridericia's formula) before versus after treatment (478\u00b17 vs 479\u00b17 ms, p=0.9). In high dose+, potassium increased significantly from 4.08\u00b10.29 to 4.48\u00b10.54 mmol\/L (p=0.001). However, no difference in QTcF was observed comparing before (472\u00b18 ms) versus after (469\u00b18 ms) (p=0.66) high dose<jats:italic>+<\/jats:italic> treatment. No patients developed hyperkalaemia.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusion<\/jats:title>\n                  <jats:p>In patients with LQTS, high dose<jats:italic>+<\/jats:italic> treatment increased plasma potassium by 0.4 mmol\/L without cases of hyperkalaemia. However, the potassium increase did not shorten the QT interval and several patients had side effects. Considering the QT interval as a proxy for arrhythmic risk, our data do not support that potassium-elevating treatment has a role as antiarrhythmic prophylaxis in patients with LQTS with normal-range potassium levels.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Trial registration number<\/jats:title>\n                  <jats:p>\n                     <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"clintrialgov\" xlink:href=\"NCT03291145\">NCT03291145<\/jats:ext-link>.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/openhrt-2021-001670","type":"journal-article","created":{"date-parts":[[2021,9,16]],"date-time":"2021-09-16T12:50:15Z","timestamp":1631796615000},"page":"e001670","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":7,"title":["Effect of moderate potassium-elevating treatment in long QT syndrome: the TriQarr Potassium Study"],"prefix":"10.1136","volume":"8","clinical-trial-number":[{"clinical-trial-number":"nct03291145","registry":"10.18810\/clinical-trials-gov"}],"author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1766-181X","authenticated-orcid":false,"given":"Peter","family":"Marstrand","sequence":"first","affiliation":[{"name":"Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kasim","family":"Almatlouh","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J\u00f8rgen K","family":"Kanters","sequence":"additional","affiliation":[{"name":"Laboratory of Experimental Cardiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claus","family":"Graff","sequence":"additional","affiliation":[{"name":"Department of Health Science and Technology, Aalborg University, Aalborg, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alex H\u00f8rby","family":"Christensen","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Henning","family":"Bundgaard","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juliane","family":"Theilade","sequence":"additional","affiliation":[{"name":"Department of Cardiology, Herlev-Gentofte Hospital, Copenhagen University Hospital, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2021,9,16]]},"reference":[{"key":"2025081710114212000_8.2.e001670.1","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.101.6.616"},{"key":"2025081710114212000_8.2.e001670.2","doi-asserted-by":"publisher","DOI":"10.1093\/europace\/eut272"},{"key":"2025081710114212000_8.2.e001670.3","doi-asserted-by":"publisher","DOI":"10.1161\/CIR.0000000000000549"},{"key":"2025081710114212000_8.2.e001670.4","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacc.2003.07.006"},{"key":"2025081710114212000_8.2.e001670.5","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.94.5.1018"},{"key":"2025081710114212000_8.2.e001670.6","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacc.2008.07.054"},{"key":"2025081710114212000_8.2.e001670.7","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1016\/j.hrthm.2020.08.017","article-title":"Long QT syndrome type 1 and 2 patients respond differently to arrhythmic triggers: The TriQarr in vivo study","volume":"18","author":"Marstrand","year":"2021","journal-title":"Heart Rhythm"},{"key":"2025081710114212000_8.2.e001670.8","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacc.2009.12.015"},{"key":"2025081710114212000_8.2.e001670.9","doi-asserted-by":"publisher","DOI":"10.1016\/j.hrthm.2008.03.037"},{"key":"2025081710114212000_8.2.e001670.10","doi-asserted-by":"publisher","DOI":"10.2165\/00002018-200932070-00006"},{"key":"2025081710114212000_8.2.e001670.11","first-page":"409","volume-title":"R: A Language and Environment for Statistical Computing, version 3.6.1. 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