Circulating microRNAs (miRNAs) may represent a novel class of biomarkers; therefore, we examined whether acute myocardial infarction (MI) modulates miRNAs plasma levels in humans and mice. Healthy donors (n = 17) and patients (n = 33) with acute ST-segment elevation MI (STEMI) were evaluated. In one cohort (n = 25), the first plasma sample was obtained 517 ± 309 min after the onset of MI symptoms and after coronary reperfusion with percutaneous coronary intervention (PCI); miR-1, -133a, -133b, and -499-5p were ∼15- to 140-fold control, whereas miR-122 and -375 were ∼87–90% lower than control; 5 days later, miR-1, -133a, -133b, -499-5p, and -375 were back to baseline, whereas miR-122 remained lower than control through Day 30. In additional patients (n = 8; four treated with thrombolysis and four with PCI), miRNAs and troponin I (TnI) were quantified simultaneously starting 156 ± 72 min after the onset of symptoms and at different times thereafter. Peak miR-1, -133a, and -133b expression and TnI level occurred at a similar time, whereas miR-499-5p exhibited a slower time course. In mice, miRNAs plasma levels and TnI were measured 15 min after coronary ligation and at different times thereafter. The behaviour of miR-1, -133a, -133b, and -499-5p was similar to STEMI patients; further, reciprocal changes in the expression levels of these miRNAs were found in cardiac tissue 3–6 h after coronary ligation. In contrast, miR-122 and -375 exhibited minor changes and no significant modulation. In mice with acute hind-limb ischaemia, there was no increase in the plasma level of the above miRNAs. Acute MI up-regulated miR-1, -133a, -133b, and -499-5p plasma levels, both in humans and mice, whereas miR-122 and -375 were lower than control only in STEMI patients. These miRNAs represent novel biomarkers of cardiac damage.

Patients with acute myocardial infarction undergoing primary angioplasty are at high risk for contrast-medium–induced nephropathy because of hemodynamic instability, the need for a high volume of contrast medium, and the lack of effective prophylaxis. We investigated the antioxidant N-acetylcysteine for the prevention of contrast-medium–induced nephropathy in patients undergoing primary angioplasty. We randomly assigned 354 consecutive patients undergoing primary angioplasty to one of three groups: 116 patients were assigned to a standard dose of N-acetylcysteine (a 600-mg intravenous bolus before primary angioplasty and 600 mg orally twice daily for the 48 hours after angioplasty), 119 patients to a double dose of N-acetylcysteine (a 1200-mg intravenous bolus and 1200 mg orally twice daily for the 48 hours after intervention), and 119 patients to placebo. The serum creatinine concentration increased 25 percent or more from baseline after primary angioplasty in 39 of the control patients (33 percent), 17 of the patients receiving standard-dose N-acetylcysteine (15 percent), and 10 patients receiving high-dose N-acetylcysteine (8 percent, P<0.001). Overall in-hospital mortality was higher in patients with contrast-medium–induced nephropathy than in those without such nephropathy (26 percent vs. 1 percent, P<0.001). Thirteen patients (11 percent) in the control group died, as did five (4 percent) in the standard-dose N-acetylcysteine group and three (3 percent) in the high-dose N-acetylcysteine group (P=0.02). The rate for the composite end point of death, acute renal failure requiring temporary renal-replacement therapy, or the need for mechanical ventilation was 21 (18 percent), 8 (7 percent), and 6 (5 percent) in the three groups, respectively (P=0.002). Intravenous and oral N-acetylcysteine may prevent contrast-medium–induced nephropathy with a dose-dependent effect in patients treated with primary angioplasty and may improve hospital outcome. (ClinicalTrials.gov number, NCT00237614.)

Nephropathy induced by exposure to radiocontrast agents, a possible complication of percutaneous coronary interventions, is associated with significant in-hospital and long-term morbidity and mortality. Patients with preexisting renal failure are at particularly high risk. We investigated the role of hemofiltration, as compared with isotonic-saline hydration, in preventing contrast-agent–induced nephropathy in patients with renal failure.

Contrast-induced nephropathy (CIN) frequently occurs in patients with acute ST-segment elevation myocardial infarction (STEMI) who are undergoing primary percutaneous coronary intervention, and CIN is associated with a more complicated clinical course and increased mortality. To investigate the association between absolute and weight- and creatinine-adjusted contrast volume, CIN incidence, and clinical outcome in the era of mechanical reperfusion of STEMI. Prospective, observational study. A university cardiology center in Milan, Italy. 561 consecutive patients with STEMI who were undergoing primary percutaneous coronary intervention. For each patient, the maximum contrast dose was calculated, according to the formula (5 × body weight [kg])/serum creatinine, and the contrast ratio, defined as the ratio between the contrast volume administered and the maximum dose calculated, was assessed. An increase in serum creatinine of more than 25% from baseline was defined as CIN. 115 (20.5%) patients developed CIN. In-hospital mortality was higher among patients with CIN than those without CIN (21.4% vs. 0.9%; P < 0.001). The maximum contrast dose was exceeded in 130 (23%) patients. Patients who received more than the maximum contrast dose (contrast ratio >1) had a more complicated in-hospital clinical course and higher mortality rate (13% vs. 2.8%; P < 0.001) than did patients with a contrast ratio less than 1. Development of CIN was associated with both contrast volume and contrast ratio. The association between contrast volume and outcomes was observed in a single center and could be due to comorbid conditions, disease severity, or an unknown factor. During primary percutaneous coronary intervention for STEMI, higher contrast volume is associated with higher rates of CIN and mortality; however, further study is needed to determine whether limiting contrast volume would improve patient outcome. Centro Cardiologico Monzino, Institute of Cardiology, University of Milan.