After an acute myocardial infarction (AMI), acute phase inflammatory markers appear to affect prognosis. C-reactive protein values are known to increase in acute coronary syndromes, such as unstable angina and myocardial infarction, and are associated with adverse outcomes. Tommasi and associates evaluated the prognostic significance of C-reactive protein values in patients considered to be at low risk for long-term adverse outcomes after a first, uncomplicated AMI and normal left ventricular function.
Venous blood samples were analyzed for C-reactive protein at a mean time of eight hours after the onset of symptoms in 64 patients with AMI. The diagnosis was confirmed by elevated creatine kinase-MB values. Follow-up testing included echocardiography and exercise stress tests (seven to eight days after the event) and coronary angiography (approximately one month after the event). Follow-up examination was conducted every three months after discharge for the next year. All patients were treated with nitrates and aspirin, and many received beta blockers with or without angiotensin-converting enzyme (ACE) inhibitors. No patient had an ejection fraction of less than 45 percent. Angiography identified the infarct-related vessel in all patients, and no patient had collateral blood vessels. Patients who died during the follow-up period had significantly higher mean C-reactive protein values. Patients with a C-reactive protein value of more than 2.55 mg per dL had a cardiac event incidence of 56 percent, including cardiac death, unstable angina and recurrent myocardial infarction. There was no correlation between C-reactive protein levels and echocardiographic ejection fraction, peak creatine kinase-MB levels, number of cigarettes smoked or plasma cholesterol levels.
The authors conclude that C-reactive protein values assayed at hospital admission can predict the risk of long-term ischemic events in patients with a first AMI who are otherwise considered to be at low risk. These assays can contribute to more complete risk stratification in these patients.