Sunday

Risk Prediction with Serial Myeloperoxidase Monitoring in Patients with Acute Chest Pain

BACKGROUND: Although myeloperoxidase (MPO) monitoring is predictive for cardiovascular outcomes in suspected acute coronary syndromes, the value of serial testing is unknown.

METHODS: We investigated the relationship between serial MPO concentrations in 490 individuals with acute chest pain and incident major adverse cardiac events (MACE) during 6 months of follow-up. We measured MPO with the CardioMPO assay, and cardiac troponin I (cTnI), with the Abbott Architect assay.

RESULTS: Plasma MPO concentrations during the first 16 h were higher in individuals who experienced MACE. Higher MPO quartiles predicted a greater likelihood of 6-month MACE at baseline [OR (95%CI), 2.4 (1.4–4.1), P = 0.001 for highest vs lowest quartile] and all subsequent time points, with strongest predictive ability found in 16-h postbaseline samples [9.9 (4.7–20.9), P < 0.001 for highest vs lowest quartile]. MPO was predictive for MACE among individuals whose cTnI remained normal (<0.028 µg/L). The lowest rate of missed cases was found when MPO was <640 pmol/L at baseline and all other time points. Serial MPO monitoring predicted MACE risk better than baseline MPO measurements alone (c statistic 0.813 vs 0.602; P = 0.002), including in individuals whose cTnI remained normal (c statistic 0.903; P = 0.009). Combined serial cTnI and MPO testing improved accuracy for predicting 6-month MACE, reduced the number of missed MACE events from cTnI testing alone, and improved risk classification in 26.1% of patients.

CONCLUSIONS: MPO concentrations are predictive of outcome up to 16 h after presentation with chest pain and predict events missed by cTnI testing, supporting a potential role in rapid patient triage.

Stephen J. Nicholls1,2,3,*, W.H. Wilson Tang1,2,3, Danielle Brennan1, Marie-Luise Brennan1,2,3, Shirley Mann2,3, Steven E. Nissen1 and Stanley L. Hazen1,2,3

1 Department of Cardiovascular Medicine, and
2 Department of Cell Biology, and
3 Center for Cardiovascular Diagnostics and Prevention, Cleveland Clinic, Cleveland, OH

Monday

Proteinase 3 and prognosis of patients with acute myocardial infarction.

Abstract
A multimarker approach may be useful for risk stratification in AMI (acute myocardial infarction) patients, particularly utilizing pathways that are pathophysiologically distinct. Our aim was to assess the prognostic value of PR3 (proteinase 3) in patients post-AMI.

We compared the prognostic value of PR3, an inflammatory marker, with an established marker NT-proBNP (N-terminal pro-B-type natriuretic peptide) post-AMI. We recruited 900 consecutive post-AMI patients (700 men; age, 64.6±12.4 years) in a prospective study with follow-up over 347 (0-764) days. Plasma PR3 was significantly higher in patients who died [666.2 (226.8-4035.5) ng/ml; P<0.001] or were readmitted with heart failure [598 (231.6-1803.9) ng/ml, P<0.004] compared with event-free survivors [486.9 (29.3-3118.2) ng/ml]. Using Cox modelling, log10 PR3 [HR (hazard ratio), 3.80] and log10 NT-proBNP (HR, 2.51) were significant independent predictors of death or heart failure.

When patients were stratified by plasma NT-proBNP (median, 1023 pmol/l), PR3 gave additional predictive value for death or heart failure, in both the patients in whom NT-proBNP level was above the median (log rank for trend, 12.54; P<0.0004) and those with NT-proBNP level below the median (log rank for trend, 3.83; P<0.05). Neither marker predicted recurrent AMI.

In conclusion, this is the first report showing a potential role for the serine protease PR3 in determining mortality and incidence of heart failure following AMI, independent of established conventional risk factors. PR3 may represent a clinically useful marker of prognosis after an AMI as part of a multimarker strategy.