Background Pump failure after acute myocardial infarction (AMI) can be predicted by several indices that estimate infarct size. However, there are few indices that predict infarct expansion and cardiac rupture. We focused on the prognostic significance of serum C-reactive protein (CRP) after AMI.

Methods and Results Serum CRP levels were measured every 24 hours in 220 patients with a first Q-wave AMI. In-hospital complications, predischarge left ventriculographic findings, and long-term prognosis were assessed in relation to peak CRP levels. Peak levels of both CRP and creatine kinase (CK) were higher in patients with pump failure than in those without pump failure. In patients with cardiac rupture, peak CRP levels were higher than in those without rupture (P=.001); peak CK levels were not predictive. Higher CRP levels were found in patients with left ventricular aneurysm (P=.001 versus those without), aggravated heart failure (P=.03 versus those without), and cardiac death (P<.0001 versus survivors) during the first year after AMI. Multivariate analysis confirmed that an elevation of the peak CRP level ≥20 mg/dL was an independent predictor of cardiac rupture (relative risk, 4.72; P=.004), left ventricular aneurysmal formation (relative risk, 2.11; P=.03), and 1-year cardiac death (relative risk, 3.44; P<.0001).

Conclusions Cardiac rupture, left ventricular aneurysmal formation, and 1-year cardiac death were associated with an elevation of serum CRP early after AMI, suggesting that elevation of CRP levels after AMI may predict infarct expansion.