High-sensitivity C-reactive protein is within normal levels at the very onset of first ST-segment elevation acute myocardial infarction in 41% of cases: a multiethnic case-control study

Abstract

Objectives: This study sought to assess the prevalence of normal levels of high sensitivity C-reactive protein (hsCRP) at the very onset of ST-segment elevation myocardial infarction (STEMI).

Background: Levels of hsCRP ≥2 mg/l identify individuals who benefit from lipid lowering and possibly anti-inflammatory agents, but how many patients develop infarction in spite of hsCRP levels <2 mg/l and thus would be ineligible for these treatments?

Methods: We studied 887 patients with unequivocally documented STEMI as the first manifestation of coronary disease and 887 matched control subjects from urban areas of Italy, Scotland, and China. Blood samples were obtained before reperfusion strategies <6 h from symptoms onset in order to limit acute event-related increases.

Results: hsCRP values were similar in samples obtained <2 h, 2 to 4 h, and 4 to 6 h from symptoms onset in all ethnic groups, consistent with the delayed hsCRP elevation after myocardial necrosis and thus indicative of pre-infarction levels. Median hsCRP values were significantly higher in patients than in control subjects: 2.49 (interquartile range [IQR]: 1.18 to 5.55) mg/l versus 1.32 (IQR: 0.58 to 3.10) mg/l (p < 0.0001), which is consistent with previous findings. However, 41% of patients had hsCRP levels <2 mg/l and conversely, 37% of control subjects had values ≥2 mg/l.

Conclusions: The measurement of hsCRP, with a 2 mg/l cutoff, would not have predicted 41% of unequivocally documented STEMIs in 3 ethnic groups without evidence of previous coronary disease, thus indicating both its limitations as an individual prognostic marker and as an indicator of a generalized inflammatory pathogenetic component of STEMI. New specific prognostic and therapeutic approaches should be found for such a large fraction of patients at risk.