Prevention of sudden cardiac arrest in dialysis patients: can we do more to improve outcomes?

Modifiable practices associated with sudden death among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study

BACKGROUND AND OBJECTIVES

Sudden death is common in hemodialysis patients, but whether modifiable practices affect the risk of sudden death remains unclear.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study analyzed 37,765 participants in 12 countries in the Dialysis Outcomes and Practice Patterns Study to explore the association of the following practices with sudden death (due to cardiac arrhythmia, cardiac arrest, and/or hyperkalemia): treatment time [TT] <210 minutes, Kt/V <1.2, ultrafiltration volume >5.7% of postdialysis weight, low dialysate potassium [K(D) <3]), and prescription of Q wave/T wave interval-prolonging drugs. Cox regression was used to estimate effects on mortality, adjusting for potential confounders. An instrumental variable approach was used to further control for unmeasured patient-level confounding.

RESULTS

There were 9046 deaths, 26% of which were sudden (crude mortality rate, 15.3/100 patient-years; median follow-up, 1.59 years). Associations with sudden death included hazard ratios of 1.13 for short TT, 1.15 for large ultrafiltration volume, and 1.10 for low Kt/V. Compared with K(D) ≥3 mEq/L, the sudden death rate was higher for K(D) ≤1.5 and K(D)=2-2.5 mEq/L. The instrumental variable approach yielded generally consistent findings. The sudden death rate was elevated for patients taking amiodarone, but not other Q wave/T wave interval-prolonging drugs.

CONCLUSIONS

This study identified modifiable dialysis practices associated with higher risk of sudden death, including short TT, large ultrafiltration volume, and low K(D). Because K(D) <3 mEq/L is common and easy to change, K(D) tailoring may prevent some sudden deaths. This hypothesis merits testing in clinical trials.

Improving ascertainment of sudden cardiac death in patients with end stage renal disease

BACKGROUND AND OBJECTIVES

Data collected by the US Renal Data System (USRDS) identify sudden cardiac death (SCD) as the leading cause of death among hemodialysis patients. However, evidence suggests that clinical events captured on the USRDS death notification form may be inaccurate. A new method for classifying SCD was recently developed to enhance the accuracy of SCD classification. This study examined the performance characteristics of this refined definition using a cohort of hemodialysis patients who experienced a witnessed SCD as the reference standard.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a retrospective cohort study of 363 patients who experienced a witnessed SCD in US Gambro (DaVita) outpatient dialysis clinics. Sensitivity of SCD defined by death notification forms and SCD defined using additional administrative sources was compared. Clinical data recorded near time of death were also examined.

RESULTS

Existing USRDS death notification forms reported 70.8% of witnessed SCD as "cardiac arrest/cause unknown" or "arrhythmia." The refined definition significantly improved identification to 83.8% of witnessed SCD events (P<0.001). Verified SCD cases that were not identified by either definition were more likely to be reported on the death notification form as death due to myocardial infarction, hyperkalemia, sepsis, malignancy, or unknown cause.

CONCLUSIONS

Compared with the death notification form alone, the refined SCD definition significantly improves the sensitivity of reporting of witnessed SCD occurring within outpatient hemodialysis clinics. More accurate reporting of cardiac events by clinicians and refinements to existing death notification forms may further improve recognition and understanding of SCD.