Abstract 11434: Low Level Elevation of Highly-Sensitive Cardiac Troponin I after Non-ST Elevation Acute Coronary Syndrome and Early Risk of Cardiac Ischemia and Ventricular Tachycardia: Analysis from MERLIN-TIMI 36
Background: In patients (pts) presenting with NSTEACS, detection of low-level elevations of cardiac troponin (cTn) using high-sensitivity assays, previously undetectable by conventional assays, is associated with increased risk of cardiovascular death or myocardial infarction. We examined whether very low-level cTn elevations are associated with subsequent detection of coronary ischemia early after hospital admission.
Methods: In MERLIN-TIMI 36, cTnI was measured in 4,155 pts with NSTEACS using a standard cTnI assay (TnI-Ultra, Siemens). A highly sensitive, single molecule cTnI assay (Erenna, Singulex, 99%ile 9pg/mL, ‘S-TnI’) was assessed in a subset of pts (n=1,231) with TnI-Ultra < 99%ile (0.04 ug/L). All pts then underwent 7-day continuous ECG (cECG) at randomization to detect ischemia (≥1mm of ST depression for ≥1 min) or ventricular tachycardia (VT ≥4 beats). Logistic regression models were adjusted for traditional risk factors.
Results: In 1,231 pts with NSTEACS and TnI-Ultra <0.04 ug/L at baseline, 16.5% developed ischemia and 19.5% developed VT on cECG. Pts with negative S-TnI had the lowest rate of ischemia (14.9%) and VT (18.1%), followed by patients with positive S-TnI but negative TnI-Ultra (19.4% and 23.1%, respectively) with the highest rate among pts with elevated TnI-Ultra (22.7% and 26.8%, respectively; p-trend <0.001 for each; figure). Furthermore, progressive S-TnI elevation among pts with negative TnI-Ultra demonstrated increasing risk of ischemia (p-trend=0.03) and VT (p-trend=0.01), even below the S-TnI 99%ile cutpoint.
Conclusion: Previously undetectable concentrations of cardiac troponin are associated with an increased risk of developing recurrent ischemia and VT detectable by continuous monitoring early after NSTEACS. These findings plausibly explain the link between low-level troponin elevations, early recurrent MI and CV death, and the benefits of early invasive management.
- © 2012 by American Heart Association, Inc.