[C-reactive protein and relative lymphocytopenia: early markers of acute myocardial infarction?]

Recent data suggest that relative lymphocytopenia and elevated C-reactive protein (CRP) are early markers of myocardial infarction. We tested these two parameters to predict myocardial infarction before elevation of creatine kinase.

Over a two-year period, 260 patients presented at the emergency room of Männedorf Hospital with suspicion of unstable angina or myocardial infarction. 197 patients were excluded because of intercurrent conditions associated with an acute-phase response or changes in leukocyte counts, as well as patients with established myocardial infarction (creatine kinase elevation at entry). The remaining 63 patients were reviewed for relative lymphocytopenia (< 20.3%) and C-reactive protein levels > 5 mg/l at admission.

Elevated levels of C-reactive protein were found in 8 of 20 patients (40%) with unstable angina and in 29 of 43 patients (67%) with myocardial infarction. A value for C-reactive protein > 5 mg/l on admission had a sensitivity of 67% and a predictive value of 78% for subsequent myocardial infarction. Relative lymphocytopenia was found in 2 patients (10%) with unstable angina and in 19 patients (44%) with myocardial infarction. The positive predictive value of both markers diagnosing myocardial infarction was 93% compared to 78% of elevated CRP or 90% of relative lymphocytopenia. In contrast, the sensitivity of both markers combined was 33%.

At present, elevation of C-reactive protein and relative lymphocytopenia allow early diagnosis of myocardial infarction. However, the markers' sensitivity is relatively low.