P196	Associations of C-reactive protein and complement C3 levels in patients with myocardial infarction.
U.K.Prasad, P.J.Grant, A.M.Carter
Academic Unit of Molecular Vascular Medicine, University of Leeds, Leeds, GB.

Background. Complement factor C3 is predictive for acute myocardial infarction (MI). C-reactive protein (CRP) is proposed to be one of the strongest independent predictors of cardiovascular disease. Hypothesis. In this study we tested the hypothesis that C3 was more strongly associated with MI than CRP. Methods. We recruited 342 Caucasian male subjects aged ≤ 65 years with acute MI diagnosed according to WHO criteria, and 197 control subjects matched for age, gender, race and domicile. Blood was obtained 3 months post MI, to minimise the bias of an acute phase response. Plasma CRP and C3 levels were determined by ELISA. Statistical analyses were carried out using the SPSS v12, and data presented as mean (95% confidence intervals). Result. C3 was significantly higher in patients with MI (1.19 [1.16–1.22] g/L) compared with controls (0.99 [0.94–1.03] g/L, p < 0.001). CRP was also significantly higher in patients (1.41 [1.24 – 1.6] mg/L) compared with controls (0.72[0.61 – 0.85], p < 0.001). In a logistic regression model including C3, age, smoking, diabetes and hypertension, C3 was independently associated with MI; the odds ratios (ORs) for MI for C3 in quartiles 2, 3 and 4 compared to quartile 1 were: 2.65 [1.56–4.50], 4.12 [2.36-7.22] and 7.88 [4.20–14.77] respectively. CRP was also independently associated with MI in a model including age, smoking diabetes and hypertension; the ORs for CRP in 2nd, 3rd and 4th quartile compared to the 1st were: 1.35 [0.80-2.27], 2.01 [1.17–3.45] and 2.49 [1.40 – 4.42] respectively. Since the magnitude of increase in OR across the quartiles of CRP was less than for C3 we included both C3 and CRP in a model with age, smoking diabetes and hypertension. C3 remained independently associated with MI with ORs for C3 in the 2nd 3rd and 4th quartiles compared to the 1st of: 2.53 [1.47–4.34], 3.83 [2.14–6.86] and 7.3 [3.73–14.27] respectively, however, CRP was not significantly associated with MI in this model (p=0.77). Conclusion: In this case-control study of MI, C3 was independently associated with MI in a model which included C3, CRP, age, smoking diabetes and hypertension, whereas CRP was not. These data suggest that elevated C3 may be superior to CRP as a marker of risk for MI.

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