Causes of early stent thrombosis in patients presenting with acute coronary syndrome: an ex vivo human autopsy study.

OBJECTIVES: The study interrogated an autopsy registry to investigate the histopathologic features of early stent thrombosis (ST) in patients presenting with acute coronary syndrome (ACS).

BACKGROUND: The occurrence of early ST following percutaneous coronary intervention (PCI) for ACS remains a clinical problem despite advances in stent technology in both bare-metal and drug-eluting stents.

METHODS: Sixty-seven stented coronary lesions from 59 patients who presented with ACS and died within 30 days were included. Stented segments were cross sectioned at 3 to 4 mm intervals and evaluated by light microscopy, and morphometric analysis was performed.

RESULTS: Early ST (<30 days of PCI) was identified in 34 (58%) of the 59 patients. Early ST was dependent on the underlying plaque morphology and underlying thrombus burden: presence of necrotic core prolapse was more frequent in thrombosed lesions compared with patent lesions (70% vs. 43%, p = 0.045) and maximal underlying thrombus thickness was significantly greater in thrombosed versus patent lesions. All 3 patients with false lumen stenting had ST. Detailed analysis revealed that the percent of necrotic core prolapse, medial tear, or incomplete apposition was significantly greater in the early ST compared with patent group (28% vs.11%, p < 0.001; 27% vs. 15% p = 0.004; and 34% vs. 18% p = 0.008, respectively). Multivariate analysis revealed that maximal depth of strut penetration, % strut with medial tear, and % struts with incomplete apposition were the primary indicators of early ST.

CONCLUSIONS: The current autopsy study highlights the impact of thrombus burden and suboptimal stent implantation in unstable lesions as a trigger of early ST, suggesting that improvement in implantation technique and refinement of stent design may improve clinical outcomes of ACS patients.