A nasty surprise: cardiogenic shock induced by extensive dissection of the left internal mammary artery graft occurring 3 months after coronary angiography-a case report.

Background: Acute dissection of the left internal mammary artery (LIMA) graft in patients with previous cardiac bypass surgery is a rare but potentially life-threatening condition.

Case Summary: A 58-year-old man with history of coronary artery disease and bypass surgery 15 years ago presented with acute coronary syndrome (non-ST-elevation myocardial infarction, NSTEMI). Angiography showed severe three-vessel disease with occlusion of a saphenous vein graft (SVG) to the first diagonal branch but patents grafts to left artery descendent (LIMA) and SVG to the right coronary artery. No coronary intervention was performed and the patient was treated medically (aspirin and ticagrelor) and discharged home after 6 days. Three months later, the patient again was admitted to the hospital with acute coronary syndrome (NSTEMI) and developing cardiogenic shock. Angiography now showed an extensive flow limiting dissection of his LIMA graft with the dissection starting at the ostium of the LIMA. After implantation of an Impella 2.5, percutaneous coronary intervention (PCI) of the graft was performed under guidance by optical coherence tomography (OCT) leading to implantation of a drug-eluting stent into the ostium of the LIMA and repeated balloon dilatations of the medial and distal parts of the graft. Antegrade flow was established and the patient's condition improved so that the Impella was removed in the cath lab. After an uneventful course, the patient was discharged home after 6 days. Elective repeat angiography after 8 weeks showed an excellent functional result without persisting signs of LIMA dissection or stenosis.

Discussion: Acute dissection of a LIMA graft is a rare event that may lead to a life-threatening condition. According to the literature, LIMA dissection happens during coronary interventions in approximately half of the cases but it also may evolve spontaneously. However, as seen from our case, there might be a substantial delay between LIMA angiography and the clinical onset of dissection. In the vast majority of cases, dissection of LIMA can be treated by PCI. The use of Impella as reported for the first time in this case may improve the safety of the procedure. In accordance to PCI of the native coronary arteries, it seems possible to leave non-flow limiting dissections in cases of extensive disease in order to avoid the late complications of complete stenting of the graft.