Inflammation in acute coronary syndromes

Inflammation is a common component of atherosclerotic plaques, and is an established consequence of myocardial ischaemia and necrosis, but it appears also to be a possible pathogenetic component that is responsible for the sudden onset of coronary instability. Systemically detectable signs of inflammation, typically represented by elevated levels of circulating C-reactive protein (CRP), are commonly detected in acute coronary syndromes. Elevated values of CRP are observed in approximately 70% of patients with severe unstable angina and are correlated with risk for developing an acute infarction in the short term. Indeed, CRP is elevated before the appearance of signs of necrosis in over 90% of patients with acute infatrtion preceded by unstable angina, but in fewer than 50% of those in whom infarction was totally unheralded. The very episodic nature and the common short duration of acute coronary syndromes suggest that the inflammatory stimuli that cause the systemically detectable inflammatory process could be unrelated to the chronic inflammatory component of the atherosclerotic background. Causes of the inflammation may be multiple and not necessarily the same in all patients, and their effect is probably modulated by the individual immunological and inflammatory response.