He has a history of non-ischaemic dilated cardiomyopathy with resistant supraventricular and ventricular tachycardias and was on concomitant beta-blockade and digoxin

He has a history of non-ischaemic dilated cardiomyopathy with resistant supraventricular and ventricular tachycardias and was on concomitant beta-blockade and digoxin. His symptoms resolved spontaneously once digoxin-specific antibody fragments were given and temporary pacing successfully performed. analysing the association between digoxin prescription in individuals on haemodialysis and survival, the authors found improved mortality in individuals on haemodialysis on digoxin, compared with matched control non-digoxin users. Lower predialysis potassium levels and higher serum digoxin concentration also correlated with increased mortality.3 Bearing this in mind, our patient had the following risk factors for digoxin toxicity, namely: chronic kidney disease on renal replacement therapy, fluctuations in serum potassium that are both diet and dialysis related and a recent decrease in his residual renal function. We suspect that he gradually accumulated digoxin as his residual output diminished and once the serum digoxin concentration surpassed the recommended restorative range, this made him feel unwell with systemic symptoms, consequently rendering him harmful with medical sequelae. In retrospect, although the fact that patient was on the lowest possible daily dose of digoxin, more demanding monitoring of his serum digoxin concentrations may have alerted us to identify chronic accumulation of the drug earlier with this high-risk patient with reduced urinary output. This case of digoxin toxicity was particularly demanding. The individuals diminished ability to renally excrete the drug, the long pauses on his ECG and the significantly raised serum digoxin concentration put him at risk of an asystolic cardiac arrest. These factors prompted the urgent insertion of a temporary pacemaker, since pharmaceutical therapy only with DigiFab would not have guaranteed an adequate response in a timely manner. The dose of DigiFab given partially neutralised the toxicity. We did not persist with full neutralisation with Fab, given that the temporary pacemaker was put. The use of Fab in digoxin toxicity in individuals with ESKD has been considered as an effective method to treat potentially life-threatening toxicity and, in fact, haemodialysis does not eliminate the Fab either. Fab therapy was found to have the same effectiveness in dialysis-dependent individuals and in those individuals with normal renal function. In dialysis-dependent individuals, however, there is improved risk of rebound digoxin toxicity, therefore more long term and demanding observation should be advocated after Fab administration.5 Serum digoxin concentration assays generally measure both unbound and bound digoxin molecules making their use unreliable after Fab administration. Immunoassays that measure free digoxin levels after Fab administration are recommended; however, these are not readily available in all centres. The clinician, consequently, must rely on medical assessment and ECG tracing to monitor initial response. In S3QEL 2 a systematic review with recommendations from EXtracorporeal TReatments In Poisoning Workgroup by Mowry discussing digoxin poisoning, the authors concluded using their data that digoxin is only slightly dialysable and that extracorporeal treatment is definitely unlikely to improve the outcomes of digoxin toxicity, regardless if Fab have been given or not.6 This applies to both modalities: haemodialysis and peritoneal dialysis. The use of restorative plasma exchange has been suggested as a method of more efficient clearance of the Fab-digoxin molecules and reduction of rebound toxicity in individuals with ESKD; however, stronger evidence is needed to support the use of this modality.7 Learning points Digoxin should be used with caution in chronic kidney disease and individuals on renal replacement therapy, especially those with reduced residual urine output. Patients undergoing regular haemodialysis classes have fluctuations in their potassium levels with hypokalaemia enhancing digoxin toxicity. Digoxin-specific antibody fragments (Fab) are recommended for the treatment of potentially life-threatening digoxin toxicity in individuals on haemodialysis. Short term cardiac pacing, CCNA2 combined with Fab therapy, can be performed in individuals with digoxin toxicity at risk of an asystolic cardiac arrest. Individuals on renal alternative therapy with digoxin S3QEL 2 toxicity should be monitored closely following Fab therapy, as they are at improved risk of S3QEL 2 rebound toxicity. Footnotes Contributors: LD was responsible for the writing and editing of the manuscript. AG was responsible for collecting data from medical records, consenting the patient and.