http://www.medpagetoday.com/Cardiology/PCI/30690
By Charles Bankhead, Staff Writer, MedPage Today
Published: January 16, 2012
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
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In patients with CKD undergoing coronary procedures, furosemide-induced high urine output with matched hydration signficantly reduced the risk of contrast induced nephropathy.
However, in another study, the use of N-acetylcysteine was not associated with improved clinical outcomes in real-world practice.
Contrast-induced nephropathy (CIN) occurred significantly less often in patients treated with a balanced diuretic-hydration protocol than those given standard isotonic saline solution, results of a randomized trial showed.
The diuretic-hydration group had a 4.6% incidence of CIN, which represented a fourfold reduction from the control group (P=0.005).
The lower incidence of CIN contributed most of the difference in a trend toward fewer in-hospital complications in the diuretic-hydration group, as reported in the January issue of Journal of the American College of Cardiology: Cardiovascular Interventions.
"This study indicates that furosemide-induced diuresis with maintenance of intravascular volume through matched hydration can be safely and effectively obtained ... and reduces the risk of CIN in high-risk patients undergoing coronary procedures," Giancarlo Marenzi, MD, of the Monzino Cardiology Center in Milan, Italy, and co-authors wrote.
The positive results were driven in large part by improved outcomes in patients with non-ST segment elevation myocardial infarction (NSTEMI) undergoing urgent angiography, a high-risk subgroup less likely to receive CIN prophylaxis.
"Although we observed an important (almost 60%) tendency toward a reduction in the incidence of CIN in elective angiography patients who were treated with [the diuresis-hydration protocol], when compared with controls, this difference did not reach statistical significance," the authors noted.
A second article in the same issue of the journal showed no benefit from use of N-acetylcysteine (NAC) to prevent CIN in more than 90,000 percutaneous coronary intervention (PCI) procedures.
Balancing Fluid Infusion and Urine Output
Prophylactic hydration with isotonic saline solution protects most patients against CIN associated with angiography. However, patients with chronic kidney disease (CKD) often receive inadequate hydration because of concerns about pulmonary edema, particularly in patients with impaired left ventricular function, the authors wrote.
Investigators in several studies employed diuretics to increase urine output and prevent overhydration. However, use of furosemide (Lasix) in the studies was associated with adverse effects, which likely resulted from vasoconstriction caused by intravascular volume depletion. This exacerbated the effects of contrast, the authors continued.
A previous study of forced diuresis, in combination with intravenous fluid replacement that matched urine output, prevented dehydration and afforded modest protection against CIN (J Am Coll Cardiol 1999; 33: 403-411). CIN-requiring dialysis did not occur in any patient who had a mean urine flow >150 mL/h.
To examine the safety and efficacy of forced diuresis with furosemide and matched hydration, Marenzi and colleagues performed a randomized trial of a proprietary system (RenalGuard) for balancing fluid infusion and urine output.
The system consists of a standard venous catheter connected to an extracorporeal circuit for fluid infusion and a standard bladder catheter for urine collection.
The trial involved patients requiring elective or urgent coronary angiography. All of the patients had CKD, which was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min/1.73 m2.
Exclusion criteria included need for primary or rescue PCI and angiography procedures requiring direct renal contrast injection.
No patient received renoprotective drugs, and non-ionic, low-osmolality contrast was used in all cases. Patients were randomized to furosemide with matched hydration or to a control group that received hydration with isotonic saline.
Patients in the furosemide group received a bolus of saline 90 minutes before the procedure administered over 30 minutes. The saline was followed by a furosemide bolus of 0.5 mg/kg administered as a single intravenous infusion.
Urine output was monitored by the system and, when urine output exceeded 300 mL/h, a patient entered the catheterization laboratory. Matched hydration continued through PCI and for four hours afterward.
In the control group, patients received a continuous IV infusion of isotonic saline, beginning 12 hours before PCI and continuing for 12 hours afterward. The total infusion was reduced by 50% for patients who had a left ventricular ejection fraction <40%.
The primary endpoint was CIN, defined as ≥25% or ≥0.5 mg/dL rise in serum creatinine during the first 72 hours after PCI.
The study included 170 patients. CIN occurred in four of 87 (4.6%) patients in the furosemide arm and 15 of 83 (18%) in the control group. The furosemide group had a cumulative incidence of inhospital complications of 8% compared with 18% in the control group (P=0.052). No device- or therapy-related complications occurred.
The study had some limitations, including the fact that it was done at a single center and was unblinded. Also, the treatment protocol used in the furosemide group was arbitrarily predetermined with regard to overall duration, furosemide dosage, and urine output target.
"Therefore, it is possible that the potential benefit of this strategy may be further improved with a greater urine output increase and/or a longer treatment period," the authors stated.
NAC in a Real-World Setting
The evaluation of NAC for prevention of CIN consisted of a review of patients who underwent non-emergent PCI during 2006 to 2009 in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium, a quality-improvement collaboration.
Investigators examined the overall prevalence of NAC use and employed propensity matching to link NAC use with clinical outcomes, including CIN, nephropathy-requiring dialysis, and death.
Of 90,578 PCI procedures during the period reviewed, 10,574 (11.6%) procedures involved use of NAC, which increases from 10.1% at the start of the review period to 13% at the end. Patients treated with NAC were older and more likely to have renal insufficiency and other comorbidities.
CIN occurred in 5.5% of patients who received NAC and in 5.5% of patients who did not receive it. The rate of nephropathy requiring dialysis was 0.6 with or without NAC, and mortality was 0.6% with NAC and 0.8% among patients who did not receive NAC.
"These findings were consistent across many prespecified subgroups," Hitinder S. Gurm, MD, of the University of Michigan in Ann Arbor, and co-authors wrote.
"Use of NAC is common and has steadily increased over the study period but does not seem to be associated with improved clinical outcomes in real-world practice," they added.
The study had some limitations. The regional registry used has an active focus on "multicentric quality improvement," which may not represent the wider population of patients undergoing PCI. In addition, the registry does not track data on the total dose of NAC administered so a dose response analysis could not be performed.
PLC Medical Systems provided the device and accessory kits for the study reported by Marenzi and collegues.
Marenzi and co-authors had no relevant disclosures.
The Blue Cross Blue Shield Michigan Cardiovascular Consortion is a registry funded by Blue Cross Blue Shield of Michigan.
Gurm and one or more co-authors disclosed relationships with Blue Cross Blue Shield Michigan. Co-authors included employees of Blue Cross Blue Shield of Michigan.
From the American Heart Association:
ACT: Acetylcysteine for the Prevention of Contrast-Induced nephropaThy (ACT) Trial
Primary source: JACC: Cardiovascular Interventions
Source reference:
Marenzi G, et al "Prevention of contrast nephropathy by furosemide with matched hydration. The MYTHOS (Induced Diuresis with Matched Hydration Compared to Standard Hydration for Contrast Induced Nephropathy Prevention) Trial" J Am Coll Cardiol Cardiovasc Intv 2012; 5: 90-97.
Additional source: JACC: Cardiovascular Interventions
Source reference:
Gurm HS, et al "Contemporary use and effectiveness of N-acetylcystein in preventing contrast-induced nephropathy among patients undergoing percutaneous coronary intervention" J Am Coll Cardiol Cardiovasc Intv 2012; 5: 98-104.
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