Effect of Tilarginine Acetate in Patients With Acute Myocardial Infarction and Cardiogenic Shock

CONTEXT: Cardiogenic shock complicating acute myocardial infarction (MI) remains a common and lethal disorder despite aggressive use of early revascularization. Systemic inflammation, including expression of inducible nitric oxide synthase (NOS) and generation of excess nitric oxide, is believed to contribute to the pathogenesis and inappropriate vasodilatation of persistent cardiogenic shock. Preliminary, single-center studies suggested a beneficial effect of NOS inhibition on hemodynamics, renal function, and survival in patients with cardiogenic shock. OBJECTIVE: To examine the effects of an isoform-nonselective NOS inhibitor in patients with MI and refractory cardiogenic shock despite establishment of an open infarct artery. DESIGN, SETTING, AND PATIENTS: International, multicenter, randomized, double-blind, placebo-controlled trial (Tilarginine Acetate Injection in a Randomized International Study in Unstable MI Patients With Cardiogenic Shock [TRIUMPH]) with planned enrollment of 658 patients at 130 centers. Participants were enrolled between January 2005 and August 2006 when the study was terminated early. INTERVENTION: Tilarginine (L-N(G)-monomethylarginine [L-NMMA]), 1-mg/kg bolus and 1-mg/kg per hour 5-hour infusion, vs matching placebo. MAIN OUTCOME MEASURES: The primary outcome was 30-day all-cause mortality among patients who received study medication. Secondary outcomes included shock resolution and duration, New York Heart Association (NYHA) functional class at 30 days, and 6-month mortality. RESULTS: Enrollment was terminated at 398 patients based on a prespecified futility analysis. Six-month follow-up was completed in February 2007. There was no difference in 30-day all-cause mortality between patients who received tilarginine (97/201 [48%]) vs placebo (76/180 [42%]) (risk ratio, 1.14; 95% confidence interval, 0.92-1.41; P = .24). Resolution of shock (133/201 [66%] tilarginine vs 110/180 [61%] placebo; P = .31) and duration of shock (median, 156 [interquartile range, 78-759] hours tilarginine vs 190 [100-759] placebo; P = .16) were similar. At 30 days a similar percentage of patients had heart failure (48% tilarginine vs 51% placebo; P = .51) with a similar percentage of those patients in NYHA class I/II (73% tilarginine vs 75% placebo; P = .27). After 6 months mortality rates were similar in the 2 groups (58% tilarginine vs 59% placebo; hazard ratio, 1.04; 95% confidence interval, 0.79-1.36; P = .80). CONCLUSIONS: Tilarginine, 1-mg/kg bolus and 5-hour infusion, did not reduce mortality rates in patients with refractory cardiogenic shock complicating MI despite an open infarct artery. Early mortality rates in this patient group are high. Further research is needed to develop effective therapies for patients with cardiogenic shock following acute MI. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00112281