Pre-PCI Hydration Feasible, Reduces Kidney Damage in STEMI Patients

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In patients with ST-segment elevation myocardial infarction (STEMI), starting hydration therapy before primary percutaneous coronary intervention (PCI) can reduce the risk of developing contrast-induced acute kidney injury (AKI) compared with either subsequent or no hydration. The findings, from a randomized trial, were published online October 4, 2011, ahead of print in Circulation: Cardiovascular Interventions.

Mauro Maioli, MD, and colleagues at the Misericordia e Dolce Hospital (Florence, Italy), randomly assigned 450 STEMI patients undergoing primary PCI to 1 of 3 strategies:

• Early hydration (sodium bicarbonate given pre- and postprocedure)
• Late hydration (isotonic saline given postprocedure)
• No hydration (control)

All patients completed the hydration protocol, with no need to prematurely terminate infusion because of fluid overload or acute pulmonary edema. Compared with late hydration, the early strategy was associated with lower median door-to-hydration time (32 min. vs. 119 min.) and higher mean total hydration volume (1,157 mL vs. 885 mL; P = 0.001 for both comparisons).

Contrast-induced AKI (primary endpoint; defined as increase in serum creatinine ≥ 25% or 0.5 mg/dL over baseline within 3 days) occurred in 20.6% of the overall cohort. The in-hospital outcomes of patients with the complication were markedly poorer than those without signs of kidney damage (table 1).

Table 1. In-Hospital Outcomes

The early hydration group experienced the lowest incidence of kidney injury and had the smallest proportion of patients with greater than 25% decrease in estimated glomerular filtration rate (eGFR) at 3 days (table 2).

Table 2. Three-Day Outcomes by Hydration Strategy

In-hospital clinical outcomes were similar across the study arms, although there was a trend toward reduced death with early vs. late or no hydration (2.0% vs. 3.3% and 5.3%, respectively; P = 0.12).

Irrespective of whether hydration was given early or late, hydration volume was inversely associated with AKI risk. On multivariable analysis, the researchers identified an optimal cutoff of 960 mL to discriminate which patients would likely develop kidney injury. Other predictors of included TIMI myocardial perfusion grade 0 to 2 and LVEF 40% or lower.

“Our findings suggest that routine procedure for patients with STEMI [who are candidates for] primary PCI should include standard pharmacological treatment associated with early hydration protocol, dosed according to patient weight and baseline [ejection fraction] and started in the emergency room whenever feasible,” the investigators conclude.

Study Design Raises Concerns

In a telephone interview, Richard J. Solomon, MD, of the University of Vermont (Burlington, VT), told TCTMD that the main message of the study is that hydration before PCI is feasible even in STEMI patients.

“What it says is that you can do prophylaxis in patients who you are rushing to get into the cath lab, so that you’re still under the 90-minute door-to-balloon time,” he said.

Similarly, Hitinder S. Gurm, MD, of the University of Michigan Medical Center (Ann Arbor, MI), was impressed that the researchers were able to accomplish randomization and hydration before PCI. “It’s generally been assumed that the emergency situation in which we treat STEMI patients—meaning the need for quick primary PCI—means that we can’t really do anything [upfront],” he said in a telephone interview with TCTMD.

But both Drs. Solomon and Gurm expressed skepticism about the study design, citing the resulting difficulty in teasing out the relative effects of bicarbonate vs. saline and early vs. late hydration. The argument that extra volume matters “may unfortunately be confounded by the fact that they used different fluids in the different groups,” Dr. Solomon cautioned.

Dr. Maioli and colleagues agree that the use of 2 different hydration agents is the main limitation of their study. “We decided to adopt 2 strategies previously experienced in emergency conditions: sodium bicarbonate has been used for rapid solution and saline solution for slow infusion,” they write. “Therefore the design of the present study makes it impossible to define which solution is to be preferred in the setting of STEMI.”

Which Agent is Best?

Debates are ongoing about whether bicarbonate or saline is more effective at reducing kidney damage, Dr. Solomon noted.

The choice of hydration agent now depends on individual center preference, he said. “A lot of institutions use bicarbonate,” including his own hospital, Dr. Solomon reported. “But there are certainly some naysayers who say bicarbonate is not an effective therapy. Saline is easier. You just pull it off the shelf. Bicarbonate you need to have made up, [though a premixed version is commercially available in Europe].”

Dr. Gurm, on the other hand, favors saline. “In some small studies—and that’s the caveat—bicarbonate seems to have an edge over saline. But when there have been well done, adequately sized studies, bicarbonate has not emerged as that beneficial,” he said. “So I think it’s important that this be repeated in a large enough cohort before we decide on this as a quality measure.”

That being said, the prehydration protocol in the current study is “very simple,” Dr. Gurm commented. “The only concern I have is that they’ve used bicarbonate, which most emergency rooms are not familiar with. And then trying to calculate 3 mL/kg for an hour and to run that on the way from the emergency room to the cath lab might be a challenge. I wish they’d just done [a prehydration] arm where they’d given them saline, because every emergency room can run saline without any problems.”

Given that ambulances often are able to perform ECGs, one option would be to start hydration during transport, Dr. Solomon suggested. In this scenario, saline would be used because the ambulance would not have sodium bicarbonate available. 

Study Details

Baseline clinical and procedural characteristics were largely similar among the 3 groups, as was contrast volume. Median door-to-balloon time was 85 minutes for each of the strategies (P = 0.31).

Early hydration involved sodium bicarbonate solution given as a 3 mL/kg bolus for 1 hour in the emergency department followed by a 1 mL/kg infusion for 12 hours after PCI. Late hydration consisted of isotonic saline given as 1 mL/kg for 12 hours after PCI.

Iodixanol (Visipaque; GE Healthcare, Amersham, UK) was the contrast medium given in all cases.

 

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Source:
Maioli M, Toso A, Leoncini M, et al. Effects of hydration in contrast-induced acute kidney injury after primary angioplasty: A randomized, controlled trial. Circ Cardiovasc Interv. 2011;Epub ahead of print.

 

 

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