Supersaturated oxygen therapy in anterior ST-elevation myocardial infarction beyond pivotal-trial criteria: A focused case series in cardiogenic shock, mechanical circulatory support, stent failure, and multivessel disease

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Background Supersaturated oxygen (SSO2) therapy delivers hyperoxemic autologous blood into the infarct-related artery after primary percutaneous coronary intervention (PCI) and reduces infarct size in selected anterior ST-elevation myocardial infarction (STEMI). Its prospective evidence base and labeled indication are confined to anterior STEMI with a de-novo culprit lesion reperfused within six hours, and exclude cardiogenic shock. Whether the therapy can practicably be delivered outside those boundaries is unreported. Methods From a single-center institutional cohort of consecutive anterior-STEMI patients treated with SSO2 after primary PCI, we identified those with one or more beyond-criteria features: cardiogenic shock or mechanical circulatory support (MCS); a non-de-novo culprit lesion (stent thrombosis or in-stent occlusion); or severe multivessel disease requiring staged revascularization. Shock severity was classified retrospectively using the Society for Cardiovascular Angiography and Interventions (SCAI) SHOCK stages. For each case we abstracted arterial access sites and sheath calibers, the route of SSO2 delivery, anticoagulation, procedural intervals, and post-PCI epicardial flow from the contemporaneous catheterization record. Results Five patients (ages 38 to 76 years; two women) met the definition. Beyond-criteria features comprised cardiogenic shock with microaxial support and severe left ventricular dysfunction with intra-aortic balloon counterpulsation; stent thrombosis and in-stent occlusion; and severe multivessel disease with staged PCI. All five completed a 60-min SSO2 infusion alongside complex revascularization, including a two-stent bifurcation strategy, intravascular lithotripsy, aspiration thrombectomy, and intracoronary imaging in every case. Four of five met the pre-specified composite definition of procedural success; the patient in cardiogenic shock achieved 0% residual stenosis but persistent TIMI grade 2 flow, and therefore did not. SSO2 required an arterial puncture that the intervention itself did not in one of four evaluable patients; in the remainder the therapy sheath was an in-place upsize of an existing arteriotomy. One patient died of refractory cardiogenic shock nine hours after PCI; the other four survived to follow-up beyond 14 months. Conclusions SSO2 was feasible to deliver across a spectrum of anterior STEMI that the pivotal trials excluded or did not study. The principal practical costs were obligatory femoral access of at least 7 French caliber, incremental access-site burden when combined with MCS, and a 60-min periprocedural dwell in unstable patients. These trade-offs, rather than the observed left ventricular trajectories, are the substantive material for anyone considering the therapy in such patients.