Hypokalaemia and atrial fibrillation detected by implanted loop recorders

Abstract

Background andAimsPotassium levels influence cardiac electrophysiology, yet their day-to-day association with atrial fibrillation (AF) remains un-clear. This study investigated the association between plasma potassium (p-potassium) and daily AF in at-risk individualsundergoing continuous electrocardiographic monitoring.Methods This is a post hoc analysis of the LOOP study randomizing participants with stroke risk factors to implantable loop recorder(ILR) screening for AF (n = 1501) or usual care. The ILR raw data were linked to p-potassium measurements collected inroutine care allowing for 1-day time difference. Associations between p-potassium and daily AF > 60 min (main outcome)were analysed using generalized and linear mixed effect models.Results The ILR data and blood tests results were available for 1334 participants combining >1.6 million days of heart rhythm mon-itoring (including 50 746 days with AF) with 12 136 p-potassium measurements. P-potassium was lower on days with AF[mean difference −.21 mmol/L (−.25; −.18)]. Self-controlled case analyses comparing AF incidence during hypokalaemia(p-potassium <3.5 mmol/L) vs in normal range yielded an incidence rate ratio of 2.24 (1.29–3.88). Hypokalaemia was pre-sent in 5.1% of days with AF lasting <60 min and 19.1% with AF lasting >240 min. Each mmol/L decrease in p-potassium wasassociated with a five-fold increase in odds of AF [adjusted odds ratio (aOR) .20 (.15–.28)], more strongly when p-potassiumdeviated from the individual’s usual value [aOR .15 (.10–.24); P-interaction = .001], and less in participants receiving diuretics[aOR .28 (.17–.47); P-interaction < .0001].Conclusions This exploratory study found that low p-potassium was associated with day-to-day AF occurrence, particularly for longerepisodes and when deviating from the individual’s usual level.