Door-to-balloon time can be more lenient in STEMI not complicated by cardiogenic shock

A longer door-to-balloon time (DTBT) of up to 180 min is not associated with worse clinical outcomes at 30 days and 1 year in patients with ST-segment elevation MI (STEMI) presenting in Killip classes I–III, according to an analysis of data from the Singapore Myocardial Infarction Registry (SMIR).

On multivariate analyses, there were no significant differences in all-cause mortality or major adverse cardiovascular events (MACE) rates at 30 days and 1 year among such patients who did not present with cardiogenic shock, regardless of whether the DTBT for primary percutaneous coronary intervention (PCI) was ≤60 min, 61–90 min, or 91–180 min (p>0.05). [Int J Cardiol 2024:413:132345]

In contrast, a DTBT for primary PCI exceeding 90 min was associated with significantly higher rates of adverse clinical outcomes in patients presenting in Killip class IV.

In this higher-risk group, after adjusting for confounders, the risk of all-cause death within 30 days and 1 year was 1.79- and 1.58-fold higher, respectively, for a DTBT of 91–180 min vs those with ≤60 min. Such delays were also associated with a 1.88- and a 1.49-fold higher risk of MACE within 30 days and 1 year, respectively.

To achieve a DTBT target or not?

Despite being a performance metric for services provided by PCI-capable hospitals, the optimal DTBT for STEMI remains controversial: both target DTBTs of ≤90 min and ≤60 min have been recommended by certain guidelines. [J Am Coll Cardiol 2013;62:e147-e239; Eur Heart J 2018;39:119-177]

“Ideally, while a DTBT as short as possible is seemingly better, this may put unnecessary stress on already overstretched healthcare systems to achieve such targets without much additional potential clinical benefit, whereby resources may have been directed to other, more meaningful initiatives,” wrote lead author Dr Samuel Koh from the Department of Cardiology, National Heart Centre Singapore, Singapore, emphasizing the rationale for the study.

To study the optimal DTBT stratified by risk and to determine whether a DTBT ≤60 min is warranted, Koh and colleagues collected information on all patients presenting with STEMI who underwent primary PCI in 2007–2019, as registered in SMIR.

The full cohort (n=13,823) was divided into three groups based on their DTBT, defined as the time from arrival at a PCI-capable hospital to the first balloon inflation during coronary intervention: ≤60 min, 61–90 min, and 91–180 min. Patients with DTBT >180 min were excluded.

About 84 percent of the overall cohort were Killip classes I–III patients (class I: 77.7 percent, class II: 3.7 percent, class III: 2.4 percent), while the rest were Killip class IV.

Cohorts by Killip class

Among Killip classes I–III patients, there were trends of increasing all-cause mortality and MACE rates at 30 days and 1 year with a longer DTBT; however, the differences were attenuated to nonsignificance on multivariate analyses.

Compared with Killip classes I–III patients, a higher proportion of Killip class IV patients required PCI for left main revascularization or triple vessel disease (1.6 percent vs 10 percent).

In this “sicker” cohort, while a DTBT >90 min conferred worse outcomes on multivariate analyses, there were no significant differences in either outcome at 30 days or 1 year between DTBT ≤60 min and 61–90 min (p>0.05).

“While DTBT is important, it is one of many actionable components of total ischaemic time," said Koh and colleagues. "Outcomes in STEMI are a complex interplay of factors, and recommendations for a reduced DTBT ≤60 min will require further evaluation.”