Cardiovascular deaths from all causes among hemodialysis (HD) patients have decreased significantly, but sudden cardiac death rates remain high, according to research presented at the National Kidney Foundation’s 2017 Spring Clinical Meetings.

From 1996 to 2013, the total cardiovascular death rate decreased 42.5%, from 12 to 6.9 per 100 patient years, according to an analysis of Medicare data conducted by the PEER kidney care initiative investigators.  But sudden cardiac death rates in the same period decreased only 19%, from 6.3 to 5.1 per 100 patient years. Sudden cardiac deaths were responsible for 52.8% of cardiac deaths in 1996, and 73.2% in 2013.

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The PEER investigators said in their 2016 report that the reasons for the decline in the overall cardiovascular death rate are debatable, but might be attributable to widespread use of beta blockers and other cardio protective medications.

The decline in overall cardiovascular mortality but not in sudden cardiac death among HD patients implies “that the underlying mechanism of sudden cardiac death in dialysis patients (and effective therapies to prevent sudden cardiac death) are different from other types of cardiovascular disease contributing to overall mortality,” the investigators wrote in their report. “If the gains evident for other types of cardiovascular mortality are to be mirrored for sudden cardiac death, a different clinical strategy appears to be needed.”

Overall cardiovascular mortality and sudden cardiac death are lower in patients initiating renal replacement therapy with peritoneal dialysis than with HD, the report noted.

“Apart from differences in demographics, plausible explanations related to the delivery of dialytic therapy may explain these striking differences in survival probability, with regard to cardiovascular or sudden cardiac mortality, between patients on hemodialysis and those on peritoneal dialysis,” the researchers wrote in the report.

“First, chronic hyperkalemia is not unusual in patients starting dialysis. Patients starting hemodialysis may be exposed to a rapid decline in serum potassium beginning at initiation of renal replacement therapy in the setting of thrice-weekly hemodialysis. Patients who may have been tolerating chronic hyperkalemia may not tolerate the rapid decline in potassium that occurs with hemodialytic therapy.

Another possible explanation may relate to the hemodynamic effects of the two dialytic therapies. Hemodialysis potentially may constitute larger cardiovascular stress in patients with an undiagnosed burden of obstructive coronary disease, which may be relatively common in dialysis patients, especially those with diabetes; initiation of hemodialysis may constitute a type of ‘hemodynamic stress test’ for occult coronary artery disease.”