By Peter Laird, MD
The most important lesson that I have learned from this years Annual Dialysis Conference 2010 is that of myocardial stunning related to current conventional dialysis practices, especially as seen in America. Although the debate over the need or lack of need for further randomized and controlled trials once again stole the headlines of this conference, the issue of myocardial stunning may be the trump card that brings into practice more frequent and less violent dialysis sessions long before the debate on RCTs is settled.
Myocardial stunning is an unexplained phenomenon related to reversible ischemia in the heart or more simply put, inadequate blood flow to the heart tissues that does not result in permanent damage. Dr. Charles Chazot presented a late afternoon discussion on how high ultrafiltration rates negatively impact cardiovascular outcomes by inducing intradialytic hypotension that the leads to reversible ischemia and myocardial stunning. An ultrafiltration rate higher than 10-12ml/hr/kg is associated with higher mortality, higher rates of intradialytic hypotension and higher rates of myocardial stunning. High Ultrafiltration rates on HD: Do they impact cardio-vascular outcome? Do they impact cardio-vascular outcome? Charles Chazot, MD, NephroCare Tassin, France:- A high UF rate is frequent, reported in 15-20% of HD patients
- A high UF rate -above 10-12ml/hr/kg-is associated with overall mortality in HD patients
- A high UF rate is associated with an increased rate of patients with cardiovascular complications present with higher UF rate
- A high UF is associated with cardiac stunning and potential long-term cardiac damage and increased mortality
- A high UF rate is associated with an increased rate of intradialytic hypotension but the association between IDH and increased mortality is not confirmed
Perhaps the most alarming news at the ADC is that this is an important phenomenon in pediatric dialysis patients as well. American dialysis practices largely ignore the simple physiologic parameter of plasma refill rates with ultrafiltration rates often exceeding this by a large factor leading to intradialytic hypotension and reversible cardiac ischemia/cardiac stunning. Treatment times greater than or equal to 240 minutes have significantly lower episodes of intradialytic hypotension with average American treatment times falling short of this parameter according to DOPPS, Longer treatment time and slower ultrafiltration in hemodialysis: associations with reduced mortality in the DOPPS:
Europe and Japan had significantly longer (P < 0.0001) average TT than the US (232 and 244 min vs 211 in DOPPS I; 235 and 240 min vs 221 in DOPPS II). Kt/V increased concomitantly with TT in all three regions with the largest absolute difference observed in Japan. TT > 240 min was independently associated with significantly lower relative risk (RR) of mortality (RR = 0.81; P = 0.0005). Every 30 min longer on HD was associated with a 7% lower RR of mortality (RR = 0.93; P < 0.0001). . . UFR > 10 ml/h/kg was associated with higher odds of intradialytic hypotension (odds ratio = 1.30; P = 0.045) and a higher risk of mortality (RR = 1.09; P = 0.02).
The HEMO study is a RCT that allegedly proved that higher intensity dialysis did not have any survival benefit, but it did not take into account ultrafiltration rates as an independent survival factor. Understanding the importance of reversible myocardial ischemia and myocardial stunning and how they relate as a prognostic factor in the incidence of sudden cardiac death of dialysis patients may turn out to be the most important survival factor in this longstanding debate. Dose of dialysis, convection and haemodialysis patients outcome—what the HEMO study doesn't tell us: the European viewpoint:
Body water volume
In the HEMO study, urea clearance was normalized by urea distribution volume. The use of Kt/V as a measure of outcome has been criticized since V independently predicts mortality when used as a surrogate for body mass and nutritional status. This could represent a drawback in the HEMO study design. However, among the HEMO study participants body water volume after dialysis did not significantly differ in any of the four arms. Therefore, from a practical point of view, this problem does not exist for the interpretation of the study results.
The solution to myocardial stunning is found in increased treatment times and frequency with concomitant reductions in ultrafiltration rates. Correlating ultrafiltration rates to plasma refill rates may turn out to be the single most important survival paradigm in dialysis treatments. Attempts to use sodium profiling to increase plasma refill rates has failed due to elevated salt loads from profiling leading to increased incidence of LVH which is also associated with increased cardiovascular death rates in dialysis patients.
The rest of the world already embraces the concept of slow and gentle dialysis with lower ultrafiltration rates, yet the American nephrology community is still waiting for a RCT to dictate practice patterns. Reversible myocardial ischemia leading to myocardial stunning renders conventional American incenter rapid ultrafiltration rates in randomized controlled studies unethical in my opinion. If the usual therapy control group therapy is unethical, then the entire RCT is likewise unethical. Myocardial stunning in dialysis patients may become the final trump card in the frequent dialysis debate once its prevalence and adverse affects become well known. For me, that was the take home message of the Annual Dialysis Conference 2010.




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Seattle 2010 - A Day of Hope
Seattle 2010 - A Day of Hope