Prognosis of myocardial infarction-related cardiogenic shock according to preadmission out-of-hospital cardiac arrest

Aims: Out-of-hospital cardiac arrest (OHCA) is highly prevalent among patients with myocardial infarction and cardiogenic shock (MI-CS). We aimed to examine the prognostic importance of OHCA in patients with MI-CS. Methods: Using Danish nationwide registries, we identified first-time hospitalized MI-CS patients (2010-2015) by OHCA status. Cumulative incidence curves and adjusted Cox regression models were used to compare in-hospital mortality, and among hospital survivors we compared 5-year rates of heart failure hospitalization and mortality. Results: We identified 3107 MI-CS patients of whom 979 presented with OHCA (32%). OHCA patients were younger (median age: 65 vs. 74 years) and had less comorbidity. In-hospital mortality was 57% in those with OHCA compared with 67% in those without, but after adjustment the hazard ratio (HR) was 0.99 [95% CI: 0.87-1.11]. Hospital survivors consisted of 1375 MI-CS patients including 531 OHCA patients (39%). Five-year mortality was 22% for OHCA patients and 42% for patients without OHCA (adjusted HR: 0.90 [95% CI: 0.70-0.1.17]). The HR for five-year cardiovascular mortality was 0.80 [95% CI: 0.62-0.98]. Lastly, 5-year rate of heart failure hospitalization was 17% for patients with OHCA compared with 34% in those without (HR: 0.44 [95% CI: 0.34-0.57]). Conclusion: Among patients hospitalized with MI-CS, OHCA did not influence all-cause in-hospital or long-term mortality but was a marker for reduced long-term rates of heart failure hospitalization and cardiovascular mortality. Future randomized studies are needed to improve prognosis of MI-CS, however, the importance of OHCA must be considered.