The timing of revascularization had no effect on the final infarct size or the occurrence of major adverse cardiac events (MACE) at one year in patients with transient STEMI, according to follow-up results of the TRANSIENT trial presented as a moderated poster Sept. 2 at ESC Congress 2019 and simultaneously published in JACC: Cardiovascular Interventions.

The TRANSIENT trial found that patients treated with either delayed (22.7 hours) or immediate (0.4 hours) revascularization had a small infarct size at four days and relatively benign outcomes at 30 days. The follow-up analysis compared four-month and one-year outcomes of a delayed vs. immediate intervention strategy.

Patients with transient STEMI were randomized to delayed or immediate intervention. The endpoints of the follow-up analysis included cardiac magnetic resonance (CMR)-assessed final infarct size and left ventricular ejection fraction (LVEF) at four months, changes from baseline to follow-up, and clinical outcomes, including MACE (comprising death, recurrent infarction, target lesion revascularization) at four and 12 months.

Of the 142 randomized patients, 72 were assigned to delayed intervention and 70 to immediate intervention. The median duration of follow-up was 366 days. A total of 138 patients had 12-month follow-up data. Follow-up CMR was performed in 54 patients in the delayed intervention group and in 56 in the immediate intervention group.

At four months, CMR demonstrated a small median final infarct size of 0.4 percent of the left ventricle in both groups (p=0.79). LVEF was similar in the delayed (59.3 percent) and immediate (59.9 percent) intervention groups. At one year, MACE had occurred in 5.7 percent of the delayed intervention group and 4.4 percent of the immediate invasive group (p=1.00). Three deaths occurred in the delayed intervention group and none in the immediate intervention group (p=0.24).

TRANSIENT, the first randomized, controlled trial to compare a delayed and immediate intervention strategy showed favorable long-term outcomes up to one year in both groups. "This knowledge can facilitate physicians in the treatment of transient STEMI patients in daily practice," write the authors.

In an accompanying editorial comment, Robert A. Byrne, MD, and Roisin Colleran, MD, write a larger and adequately powered trial for clinical outcomes is needed to answer the question of optimal timing of the invasive strategy. Meanwhile, patients should "undergo timely coronary angiography, if symptoms resolve and the ECG on arrival at the emergency department is normal – indicating spontaneous reperfusion – deferral of catheterization can be considered." They add, if the STEMI team has been activated because of initial ECG, "it would seem unreasonable to defer catheterization, with no suggestion from the trial data that a delayed strategy is associated with measurable clinical benefit."

Clinical Topics: Cardiovascular Care Team, Invasive Cardiovascular Angiography and Intervention

Keywords: ESC 19, ESC Congress, Myocardial Infarction, Percutaneous Coronary Intervention

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