C1 esterase inhibitor deficiency - a rare cause for coronary artery thrombosis

Abstract

C1 esterase inhibitor (C1-INH) is a serine protease inhibitor that acts on a number of proteins that play a role in the complement, coagulation and kinin-kallikrein cascades. By adhering to specific factors (C1, Factor XIIa, MASP-1, MASP-2, Kallikrein), it helps maintain a balance between thrombin generation and fibrinolysis. Deficient patients however exhibit an elevated thrombotic risk in response to unregulated complement activation and fibrin formation. The benefits of C1-INH as a therapeutic modality also indirectly demonstrates its physiological role. By partly modulating neutrophil dependant mechanisms, treatment with C1-INH has been shown to reduce the extent of myocardial ischaemia and reperfusion injury in animal and human models. C1-INH deficient patients are thus at a higher cardiovascular risk than the rest of the population for acute coronary thrombosis. We here describe a case of acute myocardial infarction secondary to acute coronary thrombosis as a result of C1-INH deficiency. With otherwise no evidence of coronary artery disease on angiography, a right coronary artery filling defect was consistent with acute thrombosis rather than rupture of an atherosclerotic plaque. As no other explanation was present for this event, C1-INH deficiency (giving rise to higher levels of the aforementioned factors) is thought to be the reason for this presentation, making this case report the first of its kind in the literature.