BACKGROUND: Microaxial flow pump (mAFP) use in selected patients with ST-segment–elevation myocardial infarction complicated by cardiogenic shock improves survival. The present study aimed to assess the influence of delay from first symptoms to randomization on the benefit of an mAFP in patients with ST-segment–elevation myocardial infarction complicated by cardiogenic shock. METHODS: This was a secondary analysis of the international, multicenter, randomized, open-labeled DanGer Shock trial (Danish-German Cardiogenic Shock). A total of 345 of 355 patients with ST-segment–elevation myocardial infarction and cardiogenic shock were enrolled in this substudy. Patients were stratified into quartiles according to delay from first symptoms to randomization to either an mAFP or standard care alone. The end point was death from any cause at 180 days for treatment with an mAFP versus standard of care, according to time from onset of symptoms to randomization obtained by logistic regression analysis. RESULTS: Mortality at 180 days increased across quartiles of time from onset of symptoms to randomization: Q1 (0–140 minutes), 36%; Q2 (141–248 minutes), 53%; Q3 (249–650 minutes), 59%; and Q4 (> 651 minutes), 62%, respectively (log-rank P =0.002). However, those with longer delays were also older and more often women. Median age rose from 66 years (interquartile range, 57–73) in the earliest quartile to 71 years (interquartile range, 62–79) in the latest quartile ( P =0.005), and the proportion of women increased from 15% to 34%, respectively. Combining the 3 lowest quartiles for the time from onset of symptoms to randomization, the mAFP treatment was associated with an odds ratio of 0.51 (95% CI, 0.31–0.84), whereas the odds ratio for the highest quartile was 0.92 (95% CI, 0.38–2.22; P for interaction = 0.26). CONCLUSIONS: In patients with ST-segment–elevation myocardial infarction complicated with cardiogenic shock, treatment with an mAFP was associated with reduced all-cause mortality, but the treatment benefit appeared to weaken with prolonged time from the onset of symptoms to randomization. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01633502.
Jensen et al. (Mon,) studied this question.