Study of Autopsy Registry Evaluates Causes of Early Stent Thrombosis in ACS Patients

April 23, 2014—Masataka Nakano, MD, et al published findings from an ex vivo human autopsy study to determine causes of early stent thrombosis in patients presenting with acute coronary syndrome (ACS). The study is available online ahead of print in the Journal of the American College of Cardiology (JACC).

The study was led by cardiovascular pathologist Renu Virmani, MD, who is Founder, President, and Medical Director of the CVPath Institute, Inc., in Gaithersburg, Maryland. The investigators interrogated their autopsy registry to evaluate the histopathologic features of early stent thrombosis in patients presenting with ACS. The background of the study is that the occurrence of early stent thrombosis after percutaneous coronary intervention (PCI) for ACS remains a clinical problem despite advances in stent technology in both bare-metal and drug-eluting stents.

As summarized in JACC, the study included 67 stented coronary lesions from 59 patients who presented with ACS and died within 30 days. Stented segments were cross-sectioned at 3-mm to 4-mm intervals and evaluated by light microscope; then, morphometric analysis was performed. Early stent thrombosis (< 30 days of PCI) was identified in 34 (58%) of the 59 patients.

Early stent thrombosis was dependent on the underlying plaque morphology and thrombus burden: presence of necrotic core prolapse was more frequent in thrombosed lesions compared with patent lesions (70% vs 43%; P = .045), and maximum underlying thrombus thickness was significantly greater in thrombosed versus patent lesions. All three patients with false lumen stenting had stent thrombosis. Detailed analysis revealed that the percentage of necrotic core prolapse, medial tear, or incomplete apposition was significantly greater in the early stent thrombosis group compared with the patent group (28% vs 11%, P < .001; 27% vs 15%, P = .004; and 34% vs 18%, P = .008, respectively). Multivariate analysis revealed that maximum depth of strut penetration, percent struts with medial tear, and percent struts with incomplete apposition were the primary indicators of early stent thrombosis.

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