Arrhythmic Events and Mortality in Patients With Cardiogenic Shock on Inotropic Support: Results of the DOREMI Randomized Trial

Background: Inotropic support is widely used in the management of cardiogenic shock (CS). Existing data on the incidence and significance of arrhythmic events in patients with CS on inotropic support is at high risk of bias. Methods: The Dobutamine Compared to Milrinone (DOREMI) trial randomized patients to receive dobutamine or milrinone in a double-blind fashion. Patients with and without arrhythmic events (defined as arrhythmias requiring intervention or sustained ventricular arrhythmias) were compared to identify factors associated with their occurrence, and to examine their association with in-hospital mortality and secondary outcomes. Results: Ninety-two patients (47.9%) had arrhythmic events, occurring equally with dobutamine and milrinone (P = 0.563). The need for vasopressor support at initiation of the inotrope and a history of atrial fibrillation were positively associated with arrhythmic events, whereas predominant right ventricular dysfunction, previous myocardial infarction, and increasing left ventricular ejection fraction were negatively associated with them. Supraventricular arrhythmic events were not associated with mortality (relative risk [RR], 0.97; 95% confidence interval [CI], 0.68-1.40; P = 0.879) but were positively associated with resuscitated cardiac arrests and hospital length of stay. Ventricular arrhythmic events were positively associated with mortality (RR, 1.66; 95% CI, 1.13-2.43; P = 0.026) and resuscitated cardiac arrests. Arrhythmic events were most often treated with amiodarone (97%) and electrical cardioversion (27%), which were not associated with mortality. Conclusions: Clinically relevant arrhythmic events occur in approximately one-half of patients with CS treated with dobutamine or milrinone and are associated with adverse clinical outcomes. Five factors may help to identify patients most at risk of arrhythmic events.