Prehospital delay is associated with an increased risk for 3-year all-cause mortality in patients with non–ST-segment elevation myocardial infarction (NSTEMI), according to a study published in the Journal of the American College of Cardiology.

Using data from the multicenter, prospective Korea Acute Myocardial Infarction Registry–National Institutes of Health (KAMIR–NIH), researchers evaluated the association between symptom duration and 3-year clinical outcomes among patients with NSTEMI.

Participants were categorized according to symptom-to-door (StD) time in less than 24 hours and StD in 24 hours or longer. The primary endpoint was 3-year all-cause mortality.


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Among 13,104 patients with acute myocardial infarction (AMI) in the registry, 6544 patients with NSTEMI were included in the analysis. The patients were mean aged 64.8 ± 12.3 years, 71% were men, and the median follow-up was 1098 days (IQR, 1049-1129 days).

All-cause mortality occurred in 17.0% of participants at 3 years in the StD time in 24 hours or longer group and in 10.5% of the StD time in less than 24 hours group (3-year adjusted hazard ratio [aHR] 1.35; 95% CI, 1.17-1.56; P <.001).

A composite of all-cause mortality, recurrent myocardial infarction, or hospitalization for heart failure at 3 years occurred in 23.3% of patients in the StD time in 24 hours or longer group and in 15.7% of patients in the StD time in less than 24 hours group (3-year aHR 1.24; 95% CI, 1.10-1.40; P =.001).

Subgroup analysis for age, sex, atypical chest pain, dyspnea, Q-wave in electrocardiogram, use of emergency medical services (EMS), hypertension, diabetes mellitus, chronic kidney disease, left ventricle dysfunction, thrombolysis in myocardial infarction flow, and Global Registry of Acute Coronary Events risk score found that the higher risk for all-cause mortality in the StD time in 24 hours or longer group was consistent in all subgroups.

According to multivariate logistic regression analysis, patient factors associated with prehospital delay were older age (aged ≥75 years; odds ratio [OR] 1.44; 95% CI, 1.25-1.65; P <.001), female sex (OR 1.23; 95% CI, 1.09-1.40; P =.001), symptom presentation with atypical chest pain (OR 1.61; 95% CI, 1.39-1.86; P <.001), dyspnea (OR 1.31; 95% CI, 1.15-1.49; P <.001), no use of EMS (OR 3.47; 95% CI, 2.73-4.42; P <.001), and history of diabetes mellitus (OR 1.17; 95% CI, 1.03-1.33; P <.001).

Study limitations included use of nonrandomized prospective observational registry data and the possibility of a physician-generated selection bias in the treatment strategy.

“..although our results should be interpreted with caution, this study suggests that in real-world practice, prehospital delay may affect the clinical outcomes of patients with NSTEMI,” the study authors wrote.

Reference

Cha J-J, Bae SA, Park D-W, et al. Clinical outcomes in patients with delayed hospitalization for non–ST-segment elevation myocardial infarction. J Am Coll Cardiol. Published online February 1, 2022. doi: 10.1016/j.jacc.2021.11.019