BACKGROUND Acute stent thrombosis (AST) is a serious complication of percutaneous coronary intervention (PCI). The causes of AST include the use of stents of inappropriate diameters, multiple overlapping stents, or excessively long stents; incomplete stent expansion; poor stent adhesion; incomplete coverage of dissection; formation of thrombosis or intramural hematomas; vascular injury secondary to intraoperative mechanical manipulation; insufficient dose administration of postoperative antiplatelet medications; and resistance to antiplatelet drugs. Cases of AST secondary to coronary artery spasms are rare, with only a few reports in the literature. CASE SUMMARY A 55-year-old man was admitted to the hospital with a chief complaint of back pain for 2 d. He was diagnosed with coronary heart disease and acute myocardial infarction (AMI) based on electrocardiography results and creatinine kinase myocardial band, troponin I, and troponin T levels. A 2.5 mm × 33.0 mm drug-eluting stent was inserted into the occluded portion of the right coronary artery. Aspirin, clopidogrel, and atorvastatin were started. Six days later, the patient developed AST after taking a bath in the morning. Repeat coronary angiography showed occlusion of the proximal stent, and intravascular ultrasound showed severe coronary artery spasms. The patient’s AST was thought to be caused by coronary artery spasms and treated with percutaneous transluminal coronary angioplasty. Postoperatively, he was administered diltiazem to inhibit coronary artery spasms and prevent future episodes of AST. He survived and reported no discomfort at the 2-mo follow-up after the operation and initiation of drug treatment. CONCLUSION Coronary spasms can cause both AMI and AST. For patients who exhibit coronary spasms during PCI, diltiazem administration could reduce spasms and prevent future AST.

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