Timing of revascularisation in patients with transient ST-segment elevation myocardial infarction: a randomized clinical trial

Selected in European Heart Journal by E. Asher , S. Brugaletta

This joint review is part of the PCRonline GLOBAL Journal Club Initiative by selected members of the EAPCI/PCR Journal Club and PCR NextGen, and is based on the underlying idea of “Bringing peers together, exchanging ideas, towards a common standard of care”.

Reviewers

Elad Asher

@AsherElad

Interventional cardiologist / Cardiologist

Shaarey Zedek Medical Center - Jerusalem, Israel

Salvatore Brugaletta

@sbrugaletta

Interventional cardiologist / Cardiologist

Barcelona, Spain

Our Comment

Why this study – the rationale/objective?

Patients with acute coronary syndrome who have ST-elevation on the ECG but with subsequent normalisation of the ST-segment and relief of symptoms before reperfusion therapy are referred to as transient ST-segment elevation myocardial infarction (STEMI). It is unclear what the optimal timing of revascularisation for these patients is. The aim of the study was to determine the effect of an immediate vs. a delayed invasive strategy on infarct size measured by cardiac magnetic resonance imaging (CMR).

How was it executed – the methodology?

The TRANSIENT trial was a prospective, randomised controlled clinical study, conducted in 5 high-volume PCI centres in the Netherlands. The study consisted of 142 patients with transient STEMI. Patients were randomised in a 1:1 ratio to an immediate or a delayed invasive strategy.

• Immediate invasive group - coronary angiography was initiated as soon as possible.
• Delayed invasive group - underwent coronary angiography pending on the GRACE risk score (>140 within 24 h or ≤140 within 72 h).
• Primary endpoint - MI size (% left ventricular mass) measured by CMR at 4 days.
• Secondary endpoints - Area under the curve of CK-MB and troponin T and left ventricular ejection fraction (LVEF) and volumes measured by CMR.
• Major adverse cardiac events (MACE) (death / reinfarction / target vessel revascularisation) was obtained at 30 days.
• Secondary safety endpoints – TIMI major bleeding and the need for urgent revascularisation due to signs of reinfarction.

What is the main result?

Overall, infarct size in transient STEMI was small and was not influenced by an immediate or delayed invasive strategy.

• The area under the curve of CK-MB and troponin T was also not different between groups.
• In the delayed invasive group, four patients (5.6%) underwent urgent intervention due to signs and symptoms of reinfarction, while awaiting their procedure.
• Short-term MACE was low and not different between the treatment groups (2.9% in the immediate invasive group and 2.8% in the delayed invasive group).
• The timing of the intervention did not influence the incidence of TIMI major bleeds.

Critical reading and the relevance for clinical practice

Current STEMI guidelines provide no specific recommendations for the treatment of transient STEMI. This study represents the first prospective clinical study to assess the effect of immediate vs. delayed coronary angiography in transient STEMI patients.
Interestingly, PCI was performed in a significantly higher rate in the immediate group (90% vs. 75%; P =0.03), whereas CABG was exclusively performed in the delayed group (0% vs. 11.3%; P = 0.01). That may be explained by the fact that physicians treated the delayed group more like NSTEMI patients approach.
In any case, it is interesting to see that, overall, patients with transient STEMI have a very small infarct size and a relatively benign clinical course, independent of the use of an invasive treatment strategy.
Of note, the culprit artery is likely not 100% occluded in these patients, infarct size may not be the best endpoint for evaluating the efficacy of an invasive vs. delayed invasive treatment.

Should the STEMI guidelines be changed and include specific recommendations for transient STEMI?

Whether the etiology of transient STEMI is different compared with STEMI is unknown. Patients with transient STEMI are usually younger in age, predominantly male and consisting of a high percentage of smokers. Therefore, spasm, plaque erosion and temporary thrombotic occlusion could be the underlying etiology of transient STEMI.
The authors concluded that the data complement current guidelines for both STEMI and NSTEMI, but it is unclear if it will change the current guidelines. Looking at hard clinical endpoints, the small number of patients (~70) in each group is not powered for any.
It should be considered that it is difficult to build up a study in this topic: the present study, for example, conducted in 5 high-volume PCI centres in the Netherlands, enrolled only 142 patients in almost 4 years.
For these reasons, the safety of a delayed invasive approach in these patients remains unknown.

What is your approach for those patients with transient ST-segment elevation in daily practice?