SAN DIEGO – High-dose perioperative atorvastatin treatment did not reduce acute kidney injury following elective cardiac surgery, and it may increase risk in patients with chronic kidney disease (CKD) who are naive to statin treatment, results from a large, randomized trial showed.
“Despite advances in patient management that have reduced mortality during cardiac surgery, acute kidney injury continues to complicate the postoperative course in 20%-30% of patients,” Dr. Frederic Tremaine Billings said during a press briefing at a meeting sponsored by the American Society of Nephrology.
Dr. Frederic Tremaine Billings
“Its diagnosis is independently associated with a fivefold increase in mortality following the surgery,” Dr. Tremaine added. “Statins affect several mechanisms underlying postoperative acute kidney injury. Widely prescribed to reduce cholesterol synthesis, these drugs also reduce lipid modification of intracellular signaling molecules, which have been shown to improve perfusion and reduce oxidative stress – both mechanisms important in acute kidney injury following cardiac surgery.”
Dr. Billings of the department of anesthesiology and critical care medicine at Vanderbilt University Medical Center, Nashville, Tenn., and his associates tested the hypothesis that short-term, high-dose perioperative (preoperative, intraoperative, and postoperative) atorvastatin reduces acute kidney injury (AKI) following elective cardiac surgery.
The researchers randomly assigned preoperative statin-naive patients to 80 mg of atorvastatin on the morning before surgery, 40 mg on the morning of surgery, and 40 mg daily throughout hospitalization, or to a matching placebo regimen. In addition, they randomly assigned patients who were already using statins prior to surgery to 80 mg of atorvastatin the morning of surgery, and 40 mg on the morning after surgery, or to a matching placebo regimen.
“We felt it was important to not withhold statin treatment in patients already using statins prior to surgery, beyond what is typically done in clinical practice,” Dr. Billings explained. “For this reason, preoperative statin–using subjects continued their statin up until the day before surgery, and then resumed their statin use on postoperative day 2.”
The primary endpoint of the study was the incidence of AKI as determined by Acute Kidney Injury Network criteria (a 0.3 mg/dL increase in serum creatinine concentrations within 48 hours of surgery). Secondary endpoints included the maximum creatinine increase from baseline to 48 hours after surgery, ICU delirium diagnosed by the Confusion Assessment Method for the ICU, myocardial injury, and the incidence of atrial fibrillation, pneumonia, and stroke. Safety endpoints included liver toxicity, muscle toxicity, and adverse events.
The study was limited to adults having elective cardiac surgery and excluded those with statin intolerance, acute coronary syndrome, liver dysfunction, use of CYP3A4 inhibitors, kidney transplant recipients, those currently on dialysis, and those who were pregnant.
From November 2009 to October 2014, the researchers recruited 653 patients. But the trial was halted on recommendation of Vanderbilt’s data and safety monitoring board because of futility and an increased incidence of AKI among statin-naive patients with CKD randomized to atorvastatin.
Among all patients, AKI occurred in 20.8% of those randomized to atorvastatin, compared with 19.5% of those randomized to placebo, a difference that was neither clinically nor statistically significant (P = .75), Dr. Billings reported.
However, among the 199 patients who were statin naive, AKI occurred in 21.6% of those randomized to atorvastatin, compared with 13.4% of those randomized to placebo (P = .14). “An 8% difference in the incidence of AKI is of clinical importance, if true,” he said.
Among the 36 statin-naive patients with CKD, AKI occurred in 52.9% of those randomized to atorvastatin, compared with 15.8% of those randomized to placebo (P = .03). “While the number of patients in this subgroup is small, the magnitude of effect is striking,” Dr. Billings said.
Among the 416 patients who were using statins prior to surgery, AKI occurred in 20.4% of those randomized to atorvastatin, compared with 22.4% of those randomized to placebo (P = .63). Results were similar among the subset of those patients who had CKD (31.3% vs. 36.3%; P = .59).
Safety endpoints were similar between the two groups.
Strengths of the study, Dr. Billings said, include the fact that it’s the largest randomized, controlled trial to date to test this hypothesis, the pragmatic design of the protocol, and rigorous methodology.
Limitations include the “small number of patients in the statin-naive CKD subgroup,” he noted. “And the short duration of treatment among prestudy statin-using patients could limit the observation that short-term withdrawal is not harmful – although we felt it appropriate not to limit statins beyond what’s typical in clinical practice, based on prior reports that even short-term statin withdrawal may be harmful.”