POSEIDON: Sliding-Scale Hydration Prevents CIN, Adverse Events at 6 Months

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A protocol of sliding-scale hydration based on intra-cardiac pressure measurements results in a significant reduction in both the rate of contrast-induced nephropathy (CIN) and longer-term major adverse clinical events, according to 6-month results of the POSEIDON trial presented May 9, 2013, at the annual meeting of the Society for Cardiovascular Angiography and Interventions (SCAI) in Orlando, FL.

The data were first presented in October 2012 at the Transcatheter Cardiovascular Therapeutics scientific symposium in Miami Beach, FL.

For the single-blind POSEIDON (Prevention of Contrast Renal Injury with Different Hydration Strategies) trial, Somjot S. Brar, MD, MPH, of Kaiser Permanente (Los Angeles, CA), and colleagues randomized 396 patients undergoing coronary angiography or PCI and who had stable renal insufficiency and 1 additional risk factor to left ventricular end diastolic pressure (LVEDP)-guided hydration (n = 196) or standard hydration (n = 200). Patients were treated between November 2010 and July 2012.

A Clear Advantage

LVEDP-guided hydration resulted in a 59% relative and 9.6% absolute reduction in contrast-induced nephropathy (defined as a > 25% or > 0.5 mg/dL increase in serum creatinine) primarily driven by fewer instances of increased serum creatinine more than 25% in the LVEDP-guided group (6.7% vs. 16.3%; P = 0.005). The number needed to treat (NNT) to prevent 1 instance of CIN was 10.

Multiple subgroup analyses found the treatment effect consistently in favor of LVEDP-guided hydration, with the highest trend seen in patients with diabetes (P for interaction = 0.17).

Median hydration volume was greater in the study arm compared with the standard hydration group (1,711 mL vs. 807 mL; P < 0.001).

At 6 months, those treated with sliding-scale hydration saw 68% less instances of the composite endpoint of death, MI, or dialysis compared with the standard hydration protocol (3.1% vs. 9.5%; RR 0.32; 95% CI 0.13-0.79; P = 0.008). The NNT to prevent 1 major adverse event was 16. In addition, each component of the combined endpoint was lower in the study arm (table 1).

Table 1. Major Adverse Events at 6 Months by Hydration Strategy

Lastly, stratified by CIN status, patients with CIN were more likely to experience an event or combination of events (table 2).

Table 2. Major Adverse Events at 6 Months by CIN Status

Sliding-scale hydration was stopped in 3 patients in each group (1.5% total) for shortness of breath and treatment with diuretics.

Protocol Based on Consistency

In an e-mail communication with TCTMD, Dr. Brar said he was “pleasantly surprised by the internal consistency of the results.” Since few trials have focused on long-term CIN prevention, results of POSEIDON confirm what “makes intuitive sense,” he said. “If [CIN] can be prevented, this should translate into lower rates of major adverse clinical events.”

The protocol used in the study “provides the interventionalist a concrete framework” as it is “easy to implement [and we] have found it to have little to no impact on current cath lab workflows,” Dr. Brar continued, adding that there are no additional costs associated with implementation since “LVEDP is routinely measured in the cath lab and. . .normal saline is readily available.”

Hitinder S. Gurm, MD, of the University of Michigan (Ann Arbor, MI), told TCTMD in a telephone interview that POSEIDON “makes sort of perfect sense.” Even though this is a new trial, sliding-scale hydration has been standard practice in high-risk patients at his institution, he said, but the study has “provided us with a nice protocol of how to do this.”

What Dr. Gurm found most intriguing from the results was confirmation that “when you reduce CIN, you reduce events. . . . This highlights that [CIN] is not [merely] a nuisance. It’s actually a very important complication and if we can reduce it, we can reduce long-term events. . . . There’s really no downside to [sliding-scale hydration].”

Fluid Allocation ‘Bias’?

However, Peter A. McCullough, MD, MPH, of St. John Providence Health System (Warren, MI), told TCTMD in a telephone interview that he was a bit more skeptical of the results. “The thing that doesn’t make sense is that in the LVEDP-guided group, there are 3 different levels of fluid that they can receive versus the controls,” he said. “So it doesn’t makes sense that if you look at the fluid results . . . the average fluid in the active management group should have been much lower but it wasn’t.

“Basically if you look at the treatment allocations, the opportunity to be in the LVEDP group [should be] the opportunity to get less fluid, not end up with more fluid,” Dr. McCullough continued. “This shows that more fluid is better, but the fact that it’s guided by the LVEDP [means] it should have resulted in less.”

Dr. McCullough noted that this may be explained if “things were rigged where they knew the LVEDP group and so they tried a little bit harder and gave more fluid, but this trial looks like it’s biased.” Because of this, he did not recommend making sliding-scale hydration standard practice until this issue can be straightened out.

A Strong Push Needed to Adopt as Standard Practice

Still, Dr. Gurm maintains that he is a “strong supporter” of the strategy. Going forward he said he would like to see “some kind of study showing how people can apply this into practice. More cath labs could easily start using this and applying this to what they’re doing every day.”

But, since “there’s not a drug or device . . . no one is going to be pushing for this,” he explained. “We have something that’s inexpensive but can be done automatically in every patient who comes to the cath lab and we really should consider adopting this as a standard practice.”

Future research should also focus on adjunctive hydration therapies “to help further lower the rates of [CIN],” Dr. Brar added. “Such strategies might target minimization of contrast delivery and contrast removal.”

It will also be important to identify “patients likely to benefit from sliding-scale hydration,” he continued. “Not all patients at risk for [CIN] will be candidates and not all patients are at risk for [CIN].”

Study Details

The mean age of patients was 71 years and 38% were women. Both groups received 0.9% saline at 3 mL/kg for at least 1 hour preprocedure. LVEDP was measured in all patients at the start of the procedure and prior to contrast administration. In the study arm, the fluid rate was adjusted according to the patients’ pressure as follows:

• 5 mL/kg/hr for pressure < 13 mm Hg
• 3 mL/kg/hr for 13 mm Hg to 18 mm Hg
• 1.5 mL/kg/hr for > 18 mm Hg

The standard hydration group was hydrated at 1.5 mL/kg/hr. The fluid rate was set at the start of the procedure prior to contrast exposure, and continued during the procedure and for 4 hours postprocedure.

 

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Source:
Brar SS. Sliding scale hydration for the prevention of contrast induced acute kidney injury: 6-month clinical outcomes from the POSEIDON (Prevention of Contrast Renal Injury with Different Hydration Strategies) trial. Presented at: Society for Cardiovascular Angiography and Interventions Scientific Sessions; May 9, 2013; Orlando, FL.

 

 

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