Abstract

To the Editor:

The point is well made that ST elevation on electrocardiography (ECG) may be absent within the first two hours of the onset of symptoms of acute in-stent coronary thrombosis,¹ thereby mandating a high index of clinical suspicion for this complication in patients with intracoronary stents. Such was the case in a study where the ECG did not show ST segment elevation in 13% of in-stent thrombosis episodes documented in one of the subgroups participating in an observational study of the management of in-stent thrombosis. In that study, the mean symptom-to-catheterization laboratory interval was 112 minutes.² In another report, this time involving a patient with thrombosis of the left circumflex artery stent, acute chest pain with nondiagnostic ECG changes was also a feature. In the latter instance, the interval between symptom onset and ECG documentation was not stated, and the ECG only showed a paced rhythm.³ The ECG may have been indicative of infarction in a territory other than that subtended by the thrombosed stent, as was the case in a patient who originally had a bare metal stent inserted in the left circumflex artery. Five years later, she presented with “acute inferior myocardial infarction (MI)” complicated by severe pulmonary edema, and emergency coronary angiography showed thrombosis only in the left circumflex coronary artery stent. There was associated stenosis (95%) in the mid-right coronary artery, and 70% stenosis in the proximal left anterior descending coronary artery.³ Timely action based on a high index of suspicion is, therefore, of the essence, even though typical ST segment elevation is probably more likely to occur with late presentation. This was the case in a patient who had ST segment elevation in leads I, aVL, V1-V4 >4 hours after onset of chest pain, attributable to in-stent thrombosis simultaneously involving stents situated in the left anterior descending artery and left circumflex artery, respectively.⁴ Stent thrombosis is a complication also prone to recurrence, as shown by a report where even though the interval between the two presenting features was not stated, each recurrence was characterized by the association of chest pain and ST segment elevation.⁵