ST elevation myocardial infarction due to an underexpanded stent in a heavily calcified artery

A 57-year-old man, ex-smoker, with a background of hypertension, type 2 diabetes, previous myocardial infarctions and multiple previous percutaneous coronary interventions presented acutely with a posterolateral ST-elevation myocardial infarction. There were no available medical reports describing his previous procedures as the patient was a visitor from abroad. Emergency coronary angiography revealed severe in-stent restenosis in the right coronary artery along with a severe de-novo lesion at the crux. The left anterior descending artery had a widely patent stent but severe disease distally. A large obtuse marginal of the left circumflex artery was occluded due to late stent thrombosis in the proximal segment, which was considered the culprit lesion (Figure 1 A – white arrow). The patient received loading doses of aspirin and ticagrelor.
The lesion was crossed with a standard workhorse wire and after restoring flow using a 2 mm semi-compliant balloon, it was assessed by optical coherence tomography (OCT). A focal area of severe stent underexpansion with a minimum stent area (MSA) of 1.41 mm2 was revealed (Figure 1 B). There was also severe circumferential (360°) calcification behind the stent struts, extending around 0.5 mm in depth, but not any neoatherosclerosis in front of the struts. Dilatation of the underexpanded stent was undertaken, with a 3 mm non-compliant (NC) balloon inflated at 16 atm. However, the balloon appeared to have a “dog-bone” appearance (Figure 1 C). We then inflated more aggressively up to 26 atm, but the balloon inflation still had a degree of waisting (Figure 1 D). A repeat OCT run demonstrated an improved MSA of 3.9 mm2 in the culprit lesion (Figure 1 E). We did not have access to intravascular lithotripsy. Further attempts to treat the culprit lesion by repeated inflations of greater than 20 atmospheric pressures with a 3.5 mm NC balloon helped to achieve a better angiographic result with no residual stenosis (Figures 2 A, B). A repeat OCT run confirmed good stent expansion and an MSA of around 4.75 mm2 (Figure 2 C).
At this point a decision was made to stop as further aggressive dilatation could result in coronary perforation in an already unstable patient. In addition, further lesion modification could result in no reflow, thus compromising the final result. The patient eventually remained stable with thrombolysis in myocardial infarction (TIMI) grade 3 flow and following an uncomplicated recovery he was...


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