Coronary thrombi neovascularization in patients with ST-elevation myocardial infarction - clinical and angiographic implications

- Endothelial cells are present in two thirds of aspirated thrombotic material.
- Endothelial cells are present in thrombi less than 1 day old.
- Endothelial cells' organization is associated with VEGF thrombus immunopositivity.
- Thrombus neovascularization is associated with lower myocardial perfusion after PCI.
- Thrombus angiogenesis points to longer myocardial ischemia and worse outcome.

IntroductionCoronary artery thrombosis in ST-elevation myocardial infarction (STEMI) is a dynamic process often preceded by episodes of silent plaque rupture and subocclusive thrombosis. Thrombus organization is achieved by ingrowth of endothelial and smooth muscle cells. Clinical significance and impact of thrombus neovascularization on primary percutaneous coronary intervention (pPCI) outcome remain unclear. Therefore we investigated composition and neovascularization of thrombi aspirated during pPCI and their association with clinical and angiographic parameters of STEMI patients.MethodsAspirated thrombi retrieved from 84 STEMI patients were classified as fresh (< 1 day), lytic (1-5 days) or organized (> 5 days). Thrombus neovascularization was evaluated immunohistochemically using CD34, CD31 and VEGF antibodies. CD34 and CD31 immunopositive (CD34/CD31 +) cells were organized as single, clusters and microvessels. VEGF positivity was graded as low or high, based on thrombus surface immunopositive area.ResultsCD34/CD31 + cells were present in 67% of all aspirated thrombi. Thrombus CD34/CD31 positivity was associated with previous history of angina pectoris (χ2 = 6.142, p = 0.013) and lower myocardial blush grade (MBG < 3, χ2 = 12.602, p < 0.001). Organization of CD34/CD31 + cells showed inverse association with the extent of VEGF positivity (χ2 = 10.607, p = 0.005). Fresh thrombi were associated with shorter ischemic time (U = 237.5, p = 0.002) and MBG 3 (χ2 = 6.379, p = 0.012).ConclusionsOlder thrombus age and neovascularization are associated with suboptimal myocardial perfusion in STEMI patients. Thrombus VEGF expression is inversely associated with degree of CD34 + cell organization. Therefore, neovascularization of aspirated thrombi may indicate the duration of thrombosis, coronary microcirculation status and outcome in STEMI patients.