Risk Factors for Late Stent Thrombosis

A 65-year-old man with a history of hypertension, hyperlipidemia, and coronary artery disease with a percutaneous coronary intervention (PCI) of the mid-right coronary artery 5 months ago is referred to you by his primary care physician to establish care. He reports intermittent exertional dyspnea for 1 week. He recently moved to the area and subsequently lost follow-up with his prior cardiologist. Before his stent placement, he was an avid bicyclist with excellent exercise capacity but has recently lost interest in these activities. Prior to his PCI, he had similar dyspneic symptoms and, after undergoing exercise nuclear stress testing and cardiac catheterization, had a stent placed for a 90% lesion in the mid-right coronary artery. Before moving, he had excellent follow-up and was compliant with all his medications. However, because of the stress of moving, he admits some medication noncompliance.

His prescribed medications include low-dose aspirin, clopidogrel, high-intensity atorvastatin, metoprolol tartrate 50 mg twice daily, and an angiotensin-converting enzyme inhibitor. His blood pressure is 125/72, and his heart rate is 60 bpm. An electrocardiogram in your office reveals normal sinus rhythm with an age-indeterminate infarct in the inferolateral leads. An echocardiogram reveals a left ventricular ejection fraction of 55% with no wall motion abnormalities. He is scheduled for a nuclear stress test in 1 week, but before his appointment, he experiences crushing chest pain and goes to the emergency department where an electrocardiogram shows an ST-segment elevation myocardial infarction in the inferior leads. Emergent coronary angiography shows a dominant right coronary artery with a hazy 99% stenosis at the site of his prior stent. An additional drug-eluting stent is placed, and he is transferred to the coronary care unit.

Which risk factor from the patient's history placed him at highest risk for late stent thrombosis?

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