In patients with transient ST-segment elevation myocardial infarction (STEMI), both delayed invasive treatment and immediate invasive treatment result in similar good clinical outcomes ≤1 year later, according to study results published in JACC Cardiovascular Interventions.

The study included a total of 142 patients age >18 (mean age, 61.7±11.3) years, who presented with an acute STEMI with complaints of any duration and ST-segment elevations ≥2 mm in 2 standard limb leads or 2 contiguous chest leads during a prehospital electrocardiogram. The patients also had to exhibit spontaneous, complete resolution of ST-segment elevation and complete relief of symptoms with or without treatment. Researchers randomly assigned patients 1:1 to either a delayed (median time to intervention, 22.7 hours) or immediate (median time to intervention, 0.4 hours) intervention strategy.

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Investigators determined endpoints in the current study as prespecified cardiovascular magnetic resonance imaging-assessed final infarct size and left ventricle ejection fraction at 4 months and changes from baseline to 4-month follow-up. In addition, they also documented data from the predefined clinical follow-up at 4 and 12 months, including major adverse cardiac events (MACE): defined as death, recurrent myocardial infarction, and target lesion revascularization. They conducted 1-year follow-up by telephone.


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Researchers reported that timing of revascularization had no effect on the final infarct size at 4 months or the prespecified composite endpoint of MACE. In addition, patients in both groups had very limited infarction, good ventricular function, and, subsequently, a good clinical outcome at one year. Results also show that the overall infarct size at the critical moment was already small and almost negligible at 4 months.

On the whole, the occurrence of MACE ≤1 year was low, and no between-group differences were reported (5.7% vs 4.4%, respectively, P =1). There were a total of 7 MACE by the 1-year follow-up, 4 of which occurred within one month of the initial event, and no patients died of cardiac cause.

The results of the study showed that patients with transient STEMI can be treated with either delayed or immediate invasive treatment strategies; therefore, the decision should be made on logistical considerations.

Some of the limitations of this study included how it currently is a follow-up study of the TRANSIENT study, which was not designed to detect the difference in the clinical endpoints. In addition, the results only apply to hemodynamically stable patients because hemodynamically unstable patients were not enrolled in the TRANSIENT trial. Finally, the researchers said that between-group differences in clinical management could have caused bias in the results regarding the time of coronary intervention because patients, physicians, and nurses were all aware of the assigned treatment.

Disclosure: This clinical trial was supported by unrestricted research grants from AstraZeneca Pharmaceuticals LP and BIOTRONIK. Please see the original reference for a full list of authors’ disclosures.

Reference

Janssens GN, van der Hoeven NW, Lemkes JS, et al. 1-year outcomes of delayed versus immediate intervention in patients with transient ST-segment elevation myocardial infarction [published online September 2, 2019]. JACC Cardiovasc Interv. doi:10.1016/j.jcin.2019.07.018