Antibodies to chlamydial lipopolysaccharides in unstable angina pectoris

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Abstract

Patients with coronary artery disease frequently have elevated antibody titers against Chlamydia pneumoniae, but whether antichlamydial antibody titers are correlated with prognosis in unstable angina remains unclear. We therefore investigated the sera of 1,096 patients with unstable angina regarding immunoglobulin (Ig) IgG, IgA, and IgM antibody titers against chlamydial lipopolysaccharides (LPS) and the concentrations of C-reactive protein (CRP) and troponin T (TnT). Anti-LPS IgG titers were increased in 45% of patients at enrollment and in 48% of patients at discharge (p <0.0001). Anti-LPS IgA titers were increased in 27% of patients at enrollment and in 33% of patients at discharge (p <0.0001). Patients who subsequently died had significantly lower IgM titers at enrollment than patients without events (p = 0.016). IgG, IgA, or IgM titers did not correlate with concentrations of CRP or TnT. In this large-scale study of patients with unstable angina, we frequently found elevated antichlamydial antibody titers. Patients with low IgM anti-LPS titers were at risk for subsequent death. However, there was no correlation between antichlamydial antibody titers and CRP or TnT.

Section snippets

Study population

Blood samples of a prospective investigation on the effect of abciximab on death, myocardial infarction, and repeat intervention in patients with refractory angina were analyzed. The study design and results of the C7E3 Fab Antiplatelet Therapy in Unstable Refractory Angina (CAPTURE) study have been previously published.4 In brief, patients were eligible for study participation when they had refractory unstable angina. All patients underwent angiography and a culprit lesion suitable for

Patient characteristics

Serum samples were available from 1,096 of 1,265 patients included in the CAPTURE study. The average interval between enrolment and discharge was 5.8 days. Table 1 displays clinical characteristics of the patients analyzed. Variables associated with subsequent myocardial infarction or death were high age and high concentrations of CRP or TnT at enrollment. Potential confounders such as sex, age, diabetes, or cigarette consumption had no significant effect on anti-LPS IgG, IgA, or IgM titers.

Antibody titers

IgG

Discussion

In a large cohort of patients with refractory unstable angina followed for 6 months we found no association between baseline IgG or IgA antibodies directed against chlamydial LPS and subsequent coronary events. A low initial IgM titer was an independent predictor of reinfarction or death. There was no correlation of antibody titers with serum levels of CRP, an inflammatory marker known to predict future myocardial infarction.9, 10 Likewise, we found no correlation of titers with concentrations

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