Patterns of Disease Progression and Outcomes of Inferior ST-Elevation Myocardial Infarction Complicated by Cardiogenic Shock: The Multicenter INSTINCT Registry

<b>Background</b>: Cardiogenic shock (CS) is a frequent presentation of anterior ST-elevation myocardial infarction (STEMI); however, data regarding disease progression and outcomes in inferior STEMI complicated by CS are scarce. The present study aims to analyze the prevalence, patterns of disease progression, and outcomes of inferior STEMI-CS. <b>Methods</b>: The INSTINCT (Inferior ST-elevation myocardial Infarction complicated by Cardiogenic shock) Registry retrospectively included consecutive patients who developed CS following inferior STEMI treated at three centers in Italy from 2015 to 2023. Data regarding CS stage according to the Society of Cardiovascular Angiography and Interventions (SCAI) upon diagnosis of shock and during disease progression and in-hospital outcomes were collected. Patients were defined "worsening" (WPs) if the SCAI stage increased. <b>Results</b>: A total of 130 patients developed CS after inferior STEMI and were included in the analysis, the mean age was 69.8 ± 12.4 years, and 31.5% were female. The rate of in-hospital mortality was 22.3%; predictors of in-hospital mortality were cardiopulmonary resuscitation (CPR) > 20 min or refractory cardiac arrest (CA) (OR [CI]: 9.67 [3.17-29.51]), persistently low systolic blood pressure (SBP) (OR [CI]: 12.91 [2.47-68.82]), and increase in lactates (OR [CI]: 3.53 [1.42-7.87]) during medical management. Twenty (15.4%) patients experienced worsening CS; WPs had a significantly higher rate of in-hospital mortality (13 [65%] vs. 15 [13.6%], <i>p</i> < 0.001), major bleeding (4 [20%] vs. 7 [6.4%], <i>p</i> = 0.044), and mechanical circulatory support weaning failure (7 [35%] vs. 3 [2.7%], <i>p</i> = 0.032). <b>Conclusions</b>: The in-hospital mortality rate of inferior STEMI complicated by CS was 22.3%. Predictors of in-hospital mortality included prolonged CPR, persistently low SBP, and elevated lactates. Progression through SCAI stages was rare but associated with significantly higher mortality and complication rates.