A nightmare of clopidogrel resistance in a resource-limited setting: case report of subacute stent thrombosis
Authors: Pallangyo Pedro , Bhalia Smita V. , Komba Makrina , Mkojera Zabella S. , Mayala Henry A. , Kifai Engerasiya , Kisenge Peter R. 
Published: October 2023

Abstract
Background
Stent thrombosis, a life-threatening complication of percutaneous coronary intervention (PCI) continues to occur despite effective antiplatelet regimens and improved stenting methods. Noncompliance with dual antiplatelet therapy is the most common etiology; however, in spite of timely and their optimum administration the rates of recurrent myocardial infarction (MI) and stent thrombosis remain high. Clopidogrel resistance is increasingly evoked with elevated risk of anterothrombotic events particularly in the setting of stent implantation. In this case report, we present a case of subacute stent thrombosis associated with clopidogrel resistance in a resource-constrained setting.

Case presentation
A 60 year old man with a long standing history of hypertension presented with a 6-month history of progressive shortness of breath. Initial electrocardiogram (ECG) revealed T-wave inversion on lateral leads and echocardiogram revealed akinetic basal lateral wall and hypokinetic mid lateral wall with reduced systolic functions. An elective coronary angiography (CAG) revealed a 90% stenosis of mid left anterior descending (LAD) artery and an 80% stenosis on the proximal left circumflex artery. He underwent a successful PCI with a drug-eluting stent implantation to mid LAD. He was discharged in a stable state 48 h post revascularization with dual antiplatelet (clopidogrel and acetylsalicylic acid). Seven days later, he presented with a crushing substernal chest pain. Cardiac enzymes were elevated and ECG revealed anterior ST-elevation MI. An emergency CAG revealed a high thrombus burden with 100% occlusion of mid LAD. Following unsuccessful ballooning, intravenous and intracoronary thrombolysis with tenecteplase was given. A TIMI II flow was achieved and the patient was sent to the coronary care unit. However, 14 h later there was yet a new onset of severe chest pain. A 12-lead ECG previewed anterior ST-elevation MI and the cardiac enzymes were high. Urgent CAG revealed in-stent thrombotic total occlusion of mid LAD. A stent in stent was then implanted and TIMI III flow was restored. Clopidogrel resistance was suspected and the patient was transitioned to ticagrelol. There were no further ischemic events during the remainder of hospitalization and the patient was discharged in a hemodynamically stable state three days later. During follow-up after one and three months, he was fairly stable without any further cardiac events.

Conclusions
Owing to clopidogrel resistance, stent thrombosis in the setting of dual antiplatelet therapy compliance may occur. While in a situation of clopidogrel resistance newer and more potent antiplatelet drugs should be used, their availability and cost remains a significant barrier particularly in the developing world. Nonetheless, a high index of suspicion and timely revascularization is fundamental to restore patency of the thrombosed vessel and confer better risk-adjusted survival rates.