Role of ST2 in non-ST-elevation acute coronary syndrome in the MERLIN-TIMI 36 trial.

OBJECTIVE: We investigated the prognostic performance of ST2 with respect to cardiovascular death (CVD) and heart failure (HF) in patients with non-ST-elevation acute coronary syndrome (NSTE-ACS) in a large multinational trial.

BACKGROUND: Myocytes that are subjected to mechanical stress secrete ST2, a soluble interleukin-1 receptor family member that is associated with HF after STE-ACS.

METHODS: We measured ST2 with a high-sensitivity assay in all available baseline samples (N=4426) in patients enrolled in the Metabolic Efficiency With Ranolazine for Less Ischemia in the Non-ST-Elevation Acute Coronary Syndrome Thrombolysis in Myocardial Infarction 36 (MERLIN-TIMI 36), a placebo-controlled trial of ranolazine in NSTE-ACS. All events, including cardiovascular death and new or worsening HF, were adjudicated by an independent events committee.

RESULTS: Patients with ST2 concentrations in the top quartile (>35 μg/L) were more likely to be older and male and have diabetes and renal dysfunction. ST2 was only weakly correlated with troponin and B-type natriuretic peptide. High ST2 was associated with increased risk for CVD/HF at 30 days (6.6% vs 1.6%, P<0.0001) and 1 year (12.2% vs 5.2%, P<0.0001). The risk associated with ST2 was significant after adjustment for clinical covariates and biomarkers (adjusted hazard ratio CVD/HF 1.90, 95% CI 1.15-3.13 at 30 days, P=0.012; 1.51, 95% CI 1.15-1.98 at 1 year, P=0.003), with a significant integrated discrimination improvement (P<0.0001). No significant interaction was found between ST2 and ranolazine (Pinteraction=0.15).

CONCLUSIONS: ST2 correlates weakly with biomarkers of acute injury and hemodynamic stress but is strongly associated with the risk of HF after NSTE-ACS. This biomarker and related pathway merit further investigation as potential therapeutic targets for patients with ACS at risk for cardiac remodeling.