Correlation Study Between Intravascular Ultrasound Features Of Atherosclerotic Plaque And Tissue Factor

[Objective] To investigate the morphological features of atherosclerotic plaques by intravascular ultrasound (IVUS) in patients with stable angina (SA) and patients with unstable angina (UA) .And to investigate the change of plasma tissue factor (TF) activity in patients with stable and unstable plaques. [Methods] IVUS was used to analyze the coronary lesions in 9 patients with SA and 12 patients with UA who were in hospital since march 2006 to September 2006．. The detailed parameters involved external elastic membrane area(EEMA), luminal area (LA), plaque area(PA), area stenosis percentage, eccentric index (EI) and remodeling index (RI). According to the result of the IVUS examination the 21 patients were divided into two groups: (1) stable plaque group 13 patients; (2) unstable plaque group 8 patients. All patients were to draw blood in order to measure activity of the plasma tissue factor. Finally, The plasma tissue factor activity were measured in all of the patients. [Results] (1) IVUS found that patients in SA group mainly had stable and fibrou plaques9(100 %), while patients in UA group mainly had unstable and soft lipid plaques8(66．67%) (P<0．01) . Nonetheless, fibrous plaques were also found in UA group(4/12, 33．33%). Calcific plaques were found in SA group3(33．33%) as well as in UA group3(25．00%) with no difference(P >0．05) . Eccentric index (EI)were higher in UA group compared with SA group ( P<0．05) , and coronary segments in UA group were prone to positive remodeling9(58．00%). 2) The concentration of plasma tissue factor (TF) activity was significantly higher in unstable plaque group compared with stable plaque group (125．2±48．9 VS 256．0±52．8 P<0．01) .[Conclusion] (1) The majority of SA coronary artery lesions are stable plaques characterized by endocentric or eccentric but with low EI fibrous plaques. On the contrary, the majority of UA coronary artery lesions are mainly unstable plaques, which are more prone to positive remodeling, more eccentric and usually with large lipid pool or thin fibrosis cap. Calcific plaques are found in SA group as well as in UA group with no difference. 2) The concentration of plasma tissue factor (TF) activity was significantly higher in unstable plaque group compared with stable plaque group. The plasma tissue factor (TF) activity might reflect the unstable activity of the plaques.