Acute myocardial infarction caused by late stent thrombosis associated with progressive incomplete stent apposition

A 66-year-old woman presented with crescendo exertional chest pain. Her only risk factor for coronary artery disease was hypertension. Coronary angiography showed significant narrowing of all three coronary arteries: totally occluded right coronary artery, diffuse narrowing up to 70% of left anterior descending artery (LAD) and tubular narrowing up to 75% narrowing of the left circumflex artery (LCx). Both the LAD and the LCx were treated with drug-eluting stents (Cypher; Cordis Corporation, USA) without complications (Figure 1A). Twenty months later, she complained of chest discomfort at rest. Repeat coronary angiography showed that the LAD and LCx stents were patent, but with severe incomplete stent apposition (ISA), especially in the stented segment of LAD (Figure 1B, white arrows). Warfarin was prescribed because of the possible risk of stent thrombosis. One week later, she developed severe chest pain with ST segment elevation in the precordial leads. Her prothrombin time was 2.43 by international normalized ratio. Emergent angiography revealed total occlusion of the LAD stented segment (Figure 1C, arrow). After thrombectomy, Thrombolysis In Myocardial Infarction grade 3 flow was restored using a suction catheter, and her ST segment elevation and symptoms were relieved. The patient was then transferred for coronary artery bypass surgery. Late ISA is reported to occur in 1% to 5% of patients after bare metal stent implantation, and in 8% to 9.5% after sirolimus-eluting or paclitaxel-eluting stent implantation (1,2). There has been some concern that late ISA may be a nidus of stent thrombosis (3). However, the clinical significance is not understood, although some limited studies have reported that ISA is not associated with adverse clinical events (1,2). The number of patients enrolled in these two trials was small (13 and 33 patients, respectively), and the follow-up duration was relatively short (six and 12 months, respectively). Therefore, as indicated by our case, clinicians should carefully follow up patients who have ISA after coronary intervention, perform regular imaging studies and check for compliance with medical treatment.

Figure 1).

A Coronary angiography soon after percutaneous coronary stent implantation showing dilated left anterior descending (LAD) and left circumflex (LCx) arteries. B Coronary angiography 20 months after stent implantation showing severe out-of-stent contrast stainings at the LAD and LCx arteries (arrows), which is suggestive of incomplete stent apposition. C Emergent coronary angiography at the time of ST segment elevation myocardial infarction showing total occlusion just proximal to a previous stent (arrow) in the LAD artery. Inset shows aspirated thrombi from the LAD stent