IgM-phosphorylcholine autoantibodies and outcome in acute coronary syndromes

Antibodies against proinflammatory phosphorylcholine (anti-PC) seem to be protective and reduce morbidity. We sought to determine whether low levels of immunoglobulin-M (IgM) autoantibodies against PC add prognostic information in acute coronary syndromes (ACS).

IgM anti-PC titers were measured in serum obtained within 24h of admission from 1185 ACS patients (median age 66 years, 30% women). We evaluated major acute cardiovascular events (MACE) and all-cause mortality short--(6 months), intermediate--(18 months) and long--(72 months) terms.

Low anti-PC titers were associated with MACE and all-cause mortality at all follow-up times. After adjusting for clinical variables, plasma troponin-I, proBNP and CRP levels, associations remained at all times with MACE, short and intermediate terms also with all-cause mortality. With anti-PC titers below median, adjusted hazard ratios at 18months were for MACE 1.79 (95% confidence interval [CI]: 1.31 to 2.44; p=0.0002) and for all-cause mortality 2.28 (95% CI: 1.32 to 3.92; p=0.003). Anti-PC and plasma CRP were unrelated and added to risk prediction.

Serum IgM anti-PC titers provide prognostic information above traditional risk factors in ACS. The ease of measurement and potential therapeutic perspective indicate that it may be a valuable novel biomarker in ACS.