ORLANDO, FL — Not only does a new method of personalized sliding-scale hydration reduce the risk of contrast nephropathy in patients undergoing coronary angiography or PCI, but the treatment is also associated with a significantly lower risk of clinical events at six months[1].

Presenting the results of the POSEIDON trial at the Society for Cardiovascular Angiography and Intervention (SCAI) 2013 Scientific Sessions , lead researcher Dr Somjot Brar (Kaiser Permanente, Los Angeles, CA) reports that a hydration strategy guided by left ventricular end-diastolic pressure (LVEDP) significantly reduced the composite end point of death, MI, and the need for dialysis.

"There is a bit of a black hole in the clinical-trial literature in terms of correlating the reduction in contrast nephropathy and the risk of meaningful, hard clinical end points," Brar told heartwire . "A lot of the data showing an association of contrast nephropathy [with clinical outcomes] mostly come from registry studies. Part of the difficulty is that in negative trials, which are really the bulk of the literature, there is little motivation to follow up long term. But even if you look at a lot of positive, pivotal trials, even in these trials long-term follow-up is very rarely reported. The debate largely centers on whether or not the therapy is effective for contrast nephropathy."

As previously reported by heartwire , the POSEIDON investigators personalized hydration strategies based on the patient's LVEDP. In the trial, patients treated with the LVEDP-guided hydration and conventional-hydration strategies were administered 0.9% saline at a rate of 3 mL/kg over the course of an hour. Whereas patients in the standard arm received 1.5 mL/kg/hour during the procedure, the patients in the LVEDP-guided arm received 5 mL/kg/hour if their LVEDP was less than 13 mm Hg, 3 mL/kg/hour if the LVEDP was between 13 and 18 mm Hg, and 1.5 mL/kg/hour if their pressure exceeded 18 mm Hg.

The LVEDP-guided approach reduced the primary end point, defined as a 25% or 0.5-mg/dL increase in serum creatinine levels, 59% compared with the conventional-hydration approach. In terms of absolute risk, the tested strategy resulted in a 10% reduction in the risk of serum creatinine increases, with a number needed to treat of just 11 to prevent one case of contrast-induced nephropathy.

Following up at six months, the researchers found that the LVEDP-guided treatment significantly reduced the composite end point of death, MI, and dialysis by 68% (relative risk 0.32; 95% CI 0.13–0.79). The number needed to treat to prevent one major adverse event was 16. "For me, the six-month data showed that the story comes together in a very consistent way," said Brar.

Six-Month Composite of Major Adverse Events

Outcome LVEDP-guided hydration (%) Control (%) p
Composite of death, MI, or dialysis 3.1 9.5 0.008
Death 0.5 4.0 0.037
MI 2.0 6.5 0.029
Dialysis 0.5 2.0 0.37

While clinicians will need to measure LVEDP prior to the intervention, which would require an extra step, Brar said that the concept of measuring pressure is already established in other areas, with physicians consistently measuring pressure to assess fluid status in the coronary-care or intensive-care unit to alter therapy. "It's taking this simple concept that's been around for decades and taking the hemodynamics that we already measure in the cath lab and marrying these together to provide a solid framework in terms of how to properly hydrate patients."


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