MiD study unveils key arrhythmia findings in patients with end-stage renal disease


Medtronic has announced the results of a new study which found that atrial fibrillation and bradycardia occurred at higher than expected, and clinically significant, rates in patients with end-stage renal disease undergoing haemodialysis. Moreover, these rhythm disorders appeared to correlate with patients’ dialysis cycles, occurring immediately before, during and after their dialysis sessions.

The rhythm disorders were found in the MiD (Monitoring in dialysis) study using the Medtronic Reveal XT Insertable Cardiac Monitor (ICM). The data were presented at Kidney Week 2014: the American Society of Nephrology 47th Annual Meeting (11–16 November, Philadelphia, USA).

“It has been known that patients with end-stage renal disease are at significant risk for cardiac arrhythmias and sudden death. While it has been assumed that fluid and electrolyte imbalances are key contributors to the development of arrhythmias, other factors, including ventricular hypertrophy and cardiac fibrosis, also may exacerbate the underlying risk,” says study co-author James A Tumlin, professor, Renal Division at the University of Tennessee College of Medicine, USA. “The data presented underscore the high prevalence of arrhythmias in end-stage renal disease patients, as demonstrated by this technology, and suggest a need for intensive monitoring.”

The MiD Study monitored arrhythmias in 50 haemodialysis end-stage renal disease patients at eight sites during a six-month period using the Reveal XT ICM, a cardiac monitoring device inserted under the skin of the chest that tracks the heart’s activity for up to three years.

The preliminary analysis found that:

  • Heart arrhythmias were strongly associated with the haemodialysis schedule:Patients’ risk for cardiac rhythm problems peaked during the 12-hour interval beginning with each session, decreased for the next 12 hours, and then gradually increased during the remainder of the interdialytic interval (the interval between dialysis sessions).
  • Atrial fibrillation is commonly experienced by these patients:In the study, 52% of patients experienced atrial fibrillation. A total of 1,640 atrial fibrillation episodes of six minutes or longer were detected in 22 of 50 patients, and the rate of atrial fibrillation events was nearly four times higher in the 12 hours following dialysis.
  • Bradycardia occurred more frequently than ventricular tachycardia: In the study, 19 of 50 patients had at least one bradycardia episode (with a rate of 26 bradycardia events per patient month); there were only two sustained ventricular arrhythmia episodes during the follow-up. To date, five patients have received pacemakers following the detection of their bradycardia.

“The MiD study shows how nephrologists and cardiologists can work together to treat patients who are undergoing dialysis,” says Ven Manda, vice president of Medtronic Renal Care Solutions. “The study results give us crucial insight on the timing, frequency and types of abnormal heart rhythms experienced by these patients-especially as it relates to the delivery of dialysis-and these findings may affect how dialysis treatments are delivered in the future.”