Coronary angiography after out-of-hospital cardiac arrest

Abstract: Out-of-hospital cardiac arrest (OHCA) is a common cause of death with a survival rate of 10% in Sweden. The chance of survival depends on rapid recognition, high quality cardiopulmonary resuscitation and post-resuscitation care including searching and treating the cause of the arrest. Ischaemic cardiac disease including acute coronary artery occlusions is the most common cause of OHCA. Acute coronary artery lesions can be diagnosed and treated with coronary angiography and subsequent PCI. This thesis analyses various aspects of coronary angiography after OHCA. Paper I+II describes the rational, protocol and the results from the pilot phase (n=117) of a randomized multicentre clinical trial. We compared a strategy of immediate coronary angiography in patients successfully resuscitated after OHCA with a strategy without immediate coronary angiography. We did not reach the stipulated time of 120 minutes from first medical contact to angiography, but our study strategy was feasible. No major unexpected safety issues were reported. The main phase of the study could therefore be started with only minor changes from the pilot phase protocol.  In a registry study of 1133 patients (Paper III) coronary angiographic findings were compared with ECG and comorbidities in unconscious patients after OHCA. In patients without ST-elevation, the rate of PCI attempts was higher in patients with ST-depression (47%) and in patients with ECG classified as “other findings” (45%) compared to patients with normal ECG (33%), OR 1.78 (CI 1.13-2.82) and OR 1.65 (CI 1.04-2.61), respectively. When analysing patients without ST-elevation, no difference in PCI rates were found between the comorbidity groups and neither between patients with shockable compared to non-shockable initial ECG rhythm. Paper IV is a registry study (n=3906) analysing the impact of patient income on the probability to receive early coronary angiography after OHCA. When dividing patients into income quarters and adjusting for confounders, increasing income was associated with higher rates of early coronary angiography. Thirty-six percent of patients in the highest income quarter received early angiography compared to fifteen percent in the lowest income quarter, OR 1.64 (1.27-2.11). Adding potential mediators to explain this finding gradually decreased the difference, and the main explanatory factor for this difference was that higher income is associated with higher rates of shockable ECG rhythm. 30-day survival was also higher in the highest income quarter compared to the lowest income group in the fully adjusted analysis, OR 1.51 (CI 1.22-1.89).