The impact of coronary angiography on the clinical prognosis of successfully resuscitated out-of-hospital cardiac arrest patients without ST-segment elevation: a propensity score matching analysis

Background Previous randomized clinical trials have demonstrated that urgent coronary angiography (CAG) in patients successfully resuscitated after out-of-hospital cardiac arrest without ST-segment elevation (NSTE-OHCA) does not have a significant impact on clinical prognosis. However, the potential effect of CAG itself, including in-hospital staged CAG, in NSTE-OHCA patients has not been fully elucidated. Purpose Given that staged CAG for NSTE-OHCA patients is likely performed in candidates with a potentially favorable prognosis - introducing selection bias - we aimed to investigate the true impact of in-hospital CAG on clinical outcomes in an adjusted cohort. Methods A total of 2,593 OHCA patients were transferred to our institutional critical care center between January 2015 and December 2021. We ultimately included 252 patients who achieved the return of spontaneous circulation (ROSC) and whose electrocardiograms demonstrated non-ST-segment elevation after successful resuscitation. CAG was performed in 151 patients (59.9%) (CAG group) and not performed in 101 patients (40.1%) (non-CAG group). Propensity score (PS) matching was conducted to adjust for factors potentially affecting the indication for CAG, including age, history of coronary artery disease, initial shockable rhythm, presence of a civilian witness and bystander resuscitation, and pre-hospital ROSC. We assessed long-term clinical prognosis, including neurological status at 30 days and 1 year. Neurological status was evaluated using the cerebral performance category (CPC) scale, with favorable neurological status (FNS) defined as CPC 1-2. Results In the total NSTE-OHCA patient cohort, 122 patients (48.4%) exhibited FNS at 30 days, and 89 patients (35.3%) exhibited FNS at 1 year. In the CAG group, urgent CAG was performed in 132 patients (87.4%). The CAG group achieved a higher frequency of FNS at 30days and 1 year compared to the non-CAG group (64.2% vs 27.3%, p<0.001; 48.3% vs 15.8%, p<0.001). Before matching, CAG was a significant predictor of FNS as both 30 days and 1 year (Odds ratio (OR) 2.71, 95% Confidence interval (CI) 1.32–5.58, P<0.01 and OR 2.42, 95% CI 1.07–5.47; P=0.033). PS matching yielded 55 patients in each group. In the matched cohort, there was no significant difference in FNS between the two groups at 30 days and 1 year (51.9% vs 33.3%, P=0.079 and 32.7% vs 18.2%, P=0.125). The impact of CAG on FNS at 30 days and 1 year was not statistically significant (OR 2.15, 95% CI 0.98–4.69; P=0.053 and OR 2.19, 95% CI 0.90–5.32; P=0.083). Conclusions Although CAG was a significant predictor of favorable neurological outcomes in the unmatched cohort, its positive effect was negated after adjustment. The true impact of CAG in NSTE-OHCA patients may be influenced by selection bias.