Characteristics of hospitalizations for cardiogenic shock after acute myocardial infarction in the United States.

Background: Multiple studies have reported a decline in mortality for patients with cardiogenic shock after acute myocardial infarction (CS-AMI), a finding which has been attributed to an increase in revascularization over the past decade. However, other studies that have focused on CS-AMI patients treated with early percutaneous coronary intervention (PCI) have found no improvement in risk-adjusted mortality. To reconcile these discordances, we hypothesize that the clinical complexity of the PCI-population has changed over time, in ways not precisely adjusted for in previous studies.

Methods: We conducted a retrospective analysis of the 2005-2012 Nationwide Inpatient Sample. Patients with CS-AMI who underwent PCI within 24h of hospitalization were identified. Temporal trends in clinical characteristics and in-hospital mortality were analyzed.

Results: There was no significant change in un-adjusted in-hospital mortality (30% in 2005-2006 and 27.8% in 2011-2012, OR: 0.90; 95% CI: 0.79-1.01, p=0.07). There was an increase in the proportion of patients with ≥3 Elixhauser comorbidities and comorbidity scores ≥5. The population of patients that suffered from cardiac arrest or needed intubation on the first hospital day increased from 27.8% to 42.6% (p<0.001). In a multivariate analysis, mortality rates in 2011-2012 versus 2005-2006 decreased significantly (OR: 0.75; 95% CI: 0.65-0.85, p<0.001).

Conclusions: During a period that corresponds to expanded PCI use and improved prehospital survival, risk-adjusted mortality declined. Much of the survival benefit attributable to early revascularization has been neutralized by an increase in prevalence of "extreme-risk" patients. This may contribute to the null effect on in-hospital mortality.