In patients with non-ST-elevation myocardial infarction (NSTEMI), prehospital delay was associated with an increased risk of 3-year mortality, according to new findings from a Korean registry. The Korea-Acute-Myocardial-Infarction-Registry-National Institutes of Health (KAMIR-NIH), reported by Jung-Joon Cha, MD, of Korea University College of Medicine, Seoul, and colleagues, was published online Monday and in the Feb. 1 issue of the Journal of American College of Cardiology. The study initially enrolled 13,104 patients with acute myocardial infarction (MI) from November 2011 to December 2015. Of these, 6,544 patients presented with NSTEMI and were stratified according to symptom-to-door (StD) time of <24 hours (n=4,717) and StD time ≥24 hours (n=1,827). Symptom onset time was described as the time of onset of the last sustained chest pain. NSTEMI diagnosis was based on the criteria of the Fourth Universal Definition of MI, and patients were managed according to the current standard-of-care guideline recommendations. At baseline, the mean age of the patients was 64.8±12.3 years, and 71% were men. The primary outcome of 3-year all-cause mortality was higher in patients with StD time ≥24 hours than in the early presenters with StD time <24 hours (17.0% vs 10.5%, p<0.001). Likewise, the secondary outcome of incidence of composite of all-cause mortality, recurrent MI, hospitalization for heart failure was higher (23.3% vs 15.7%, p<0.001) in patients with StD time ≥24 hours subjects than in those with StD time <24 hours. Further, the authors noted that the observation of higher all-cause mortality in the late presenter group was consistent in the subgroup analysis with regard to age, sex, atypical chest pain, dyspnea, Q-wave in electrocardiogram, use of emergency medical services, hypertension, diabetes mellitus, chronic kidney disease, left ventricular dysfunction, Thrombolysis in Myocardial Infarction flow and the Global Registry of Acute Coronary Events risk score. Also, a multivariable analysis found that the independent predictors of delayed admission were age ≥75 years, female sex, atypical chest pain or dyspnea on presentation, diabetes and no use of emergency medical services. The authors concluded that the prehospital delay is associated with worse outcomes with higher mortality in NSTEMI patients. The key limitation of the study was the non-randomized design, which introduces the possibility of unmeasured confounders and selection bias in the treatment strategy. In an accompanying editorial, José A. Barrabés, MD, PHD and colleagues, of Universitat Autònoma de Barcelona, Barcelona, Spain, and Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares, Madrid, congratulated the authors for performing this study assessing prognostic implications of admission delays. However, the editorialists pointed out certain scenarios that remained unanswered in late presenters, such as the possibility of initial ST-elevation MI presentation that eventually resolved and secondly, that the late presenters might have had more frequent recurrent ischemic episodes, which are associated with worse prognosis. Further, Barrabés and colleagues stated that the extremely prolonged admission delay (median 72 hours) reduces the generalizability of the study results. The study was funded by the Research of Korea Centers for Disease Control and Prevention. Sources: Cha J-J, Bae S, Park D-W, et al. Clinical Outcomes in Patients With Delayed Hospitalization for Non–ST-Segment Elevation Myocardial Infarction. J Am Coll Cardiol 2022;79:311–323. Barrabés JA, Soriano-Colomé T, Ferreira-González I. When Time Is Not Muscle, Yet It Still May Be Important. J Am Coll Cardiol 2022;79:324–326. Image Credit: motortion – stock.adobe.com