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?
The correct answer is: A. Noncompliance with his dual antiplatelet therapy (DAPT).
Despite significant improvements in stent technology, stent thrombosis continues to be a considerable risk following PCI. Stent thrombosis can occur acutely (<30 days), late (30 days to <1 year), and very late (>1 year). In the SIRTAX (Sirolimus-Eluting vs. Paclitaxel-Eluting Stents for Coronary Revascularization) study, Yamaji et al. conducted a 10-year follow-up in 1,012 patients with a first-generation drug-eluting stent and estimated that the incidence of stent thrombosis is 0.67%/year for the first 5 years.1 These patients often present with an acute myocardial infarction, as was the scenario in the case presentation.
In an effort to minimize the incidence of stent thrombosis, the 2016 ACC/AHA Guideline Focused Update on Duration of Dual Antiplatelet Therapy in Patients With Coronary Artery Disease makes a Class I recommendation for DAPT for at least 1 month in a bare-metal stent and 6 months in a drug-eluting stent; however, if there are no episodes of bleeding, then DAPT should continue for 12 months in drug-eluting stents.2 Additionally, aspirin should be continued lifelong.
The correct answer in this case is noncompliance with his DAPT. A study by van Werkum et al. reviewed 21,009 patients in the Dutch stent thrombosis registry in an effort to identify predictors of stent thrombosis.3 In their analysis, early clopidogrel cessation was the strongest independent risk factor for stent thrombosis, and undersizing of the coronary stent was the second strongest predictor.3
The assumption that the patient's stent thrombosis was the results of a bare-metal stent is also incorrect. A meta-analysis by De Luca et al. comparing drug-eluting and bare-metal stents found no difference in the cumulative rate of stent thrombosis.4
Yamaji K, Räber L, Zanchin T, et al. Ten-year clinical outcomes of first-generation drug-eluting stents: the Sirolimus-Eluting vs. Paclitaxel-Eluting Stents for Coronary Revascularization (SIRTAX) VERY LATE trial. Eur Heart J 2016;37:3386-95.
Levine GN, Bates ER, Bittl JA, et al. 2016 ACC/AHA Guideline Focused Update on Duration of Dual Antiplatelet Therapy in Patients With Coronary Artery Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines: An Update of the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention, 2011 ACCF/AHA Guideline for Coronary Artery Bypass Graft Surgery, 2012 ACC/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease, 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction, 2014 AHA/ACC Guideline for the Management of Patients With Non-ST-Elevation Acute Coronary Syndromes, and 2014 ACC/AHA Guideline on Perioperative Cardiovascular Evaluation and Management of Patients Undergoing Noncardiac Surgery. Circulation 2016;134:e123-55.
van Werkum JW, Heestermans AA, Zomer AC, et al. Predictors of coronary stent thrombosis: the Dutch Stent Thrombosis Registry. J Am Coll Cardiol 2009;53:1399-409.
De Luca G, Dirksen MT, Spaulding C, et al. Drug-eluting vs bare-metal stents in primary angioplasty: a pooled patient-level meta-analysis of randomized trials. Arch Intern Med 2012;172:611-21.