Impact of treatment delay on mortality in ST-segment elevation myocardial infarction (STEMI) patients presenting with and without haemodynamic instability: results from the German prospective, multicenter FITT-STEMI trial

Selected in European Heart Journal by S. Brugaletta , D. Milasinovic

References

Authors

Karl Heinrich Scholz, Sebastian K G Maier, Lars S Maier, Björn Lengenfelder, Claudius Jacobshagen, Jens Jung, Claus Fleischmann, Gerald S Werner, Hans G Olbrich, Rainer Ott Harald Mudra, Karlheinz Seidl, P Christian Schulze, Christian Weiss, Josef Haimerl, Tim Friede, Thomas Meyer

Reference

European Heart Journal (2018) 0, 1–10

Published

February 2018

Link

Read the abstract

Our Comment

Why this study – the rationale/objective?

Total ischemic time is a known predictor of morbidity and mortality in STEMI patients treated with primary PCI. Whereas most of the existing data is based on the door-to-balloon time (D2B) as a quality metric, recent reports concentrate more on the prehospital process that is included in the concept of the first medical contact-to-balloon time. Importantly, the prehospital care, including transport to the cath lab, is complicated in patients with cardiogenic shock (CS) or out-of-hospital cardiac arrest (OHCA). The main aim of the present study was to explore the impact of the contact-to-balloon time (C2B) on survival in this high-risk STEMI subset.

How was it executed – the methodology?

  • The overall patient cohort consisted of 12 675 STEMI patients, from 48 participating PCI hospitals, with symptom onset ≤24h and the time from first medical contact to balloon inflation ≤360 mins, transported directly to a PCI center via emergency medical service (excluding self-presenters and those with inter-hospital transportation).
  • 4 groups were compared: stable patients with no CS and no OHCA, OHCA but no CS on admission to a PCI hospital, CS without OHCA, and patients with both OHCA and CS.
  • Logistic regression was used to assess the relationship of C2B with in-hospital mortality for all 4 groups.

Major findings

  • Overall in-hospital mortality in this all-comer STEMI population was 8%.
  • Mortality was the highest in patients with CS, with (45%) or without OHCA (39%), and was markedly lower in patients with OHCA only (16%). As expected, hemodynamically stable patients had the lowest mortality (2.7%).
  • C2B was prolonged in the presence of OHCA (17 min), CS (7 min) and previous CABG (11 min), whereas pre-hospital measures such as direct transport to cath lab and pre-announcement by telephone, reduced the treatment delay.
  • In the overall cohort, C2B >90 min was associated with higher mortality compared with C2B ≤90 min (12.2% vs. 3.9%, respectively, p<0.001).
  • Reducing contact-to-balloon time to <90 min was associated with a pronounced survival benefit in patients with CS (OR 0.46) or OHCA (OR 0.54).
  • For patients with CS, there was a nearly linear relationship between treatment delay and mortality (in the crucial time period from 60 to 180 minutes from the first medical contact), suggesting a 3.3 increase in the risk of death for every 10 minutes delay. 

Critical reading and the relevance for clinical practice

PCI in cardiogenic shock represents a nightmare situation for every interventional cardiologist. Despite the best PCI technique, it has usually a bad outcome, whose treatment is out of our interventional PCI possibilities. The present paper highlights the importance of the time elapsing from the first medical contact to primary PCI, if we want to improve outcome of these patients. This time emerged indeed as a strong predictor of mortality. It is noteworthy that statistical weight of delay for mortality is higher in patients with cardiogenic shock, as compared with those without, and that within patients with cardiogenic shock delay impacts more in patients without OHCA than in those with. These findings can be explained by a higher difficulty of transportation of a patient with cardiogenic shock, due to his hemodynamic instability. It can be thought also that the severity of a patient with cardiogenic shock and without OHCA may be underestimated as compared to a same situation with OHCA. In any case, it is interesting to see that there is a linear relationship between in-hospital mortality and contact-to-balloon time so that much effort should be applied in reducing this time, especially in high-risk patients.

Improving outcomes in STEMI with shock: just a matter of time?

After the hitherto randomized data failed to show mortality benefit of mechanical circulatory support (MCS) with intra-aortic balloon pump (IABP) (e.g. IABP-SHOCK trial) and Impella (e.g. IMPRESS trial), in patients with STEMI and shock, the recently published CULPRIT-SHOCK trial seems to have brought the focus back on the infarct-related artery (IRA) recanalization. The here presented FITT-STEMI study further highlights the importance of expediting PCI as soon as possible in this high-risk subset. However, before accepting the enticing premise that clinical outcomes may be most efficiently improved just by reducing the delay to reperfusion (given the linearity of the relationship between the time to PCI and mortality, it would very hard for any other intervention, e.g. MCS, to prove more impactful), at least two points may be kept in mind when interpreting the study results.

First, due to the observational study design, it could be possible that the most complex patients (i.e. those with the highest mortality risk), had undergone extensive pre-PCI diagnostics (e.g. echocardiography) and/or pharmacological therapy, thus prolonging the delay to revascularization. Furthermore, the use of MCS (IABP, ECMO) was selective, and could have, thus, confounded the impact of timing of revascularization on mortality. Second, only in-hospital mortality is reported, although long-term outcomes are of great clinical interest, especially given the observed high prevalence of multivessel disease and non-culprit chronic total occlusion (CTO) in these high-risk patients (up to 70% and 20%, respectively). Hence, timely IRA recanalization may reduce in-hospital mortality, but the presence of non-culprit lesions, including non-culprit CTO, could be a major determinant of the mid- and long-term prognosis, that is not directly influenced by the contact-to-balloon time.

Notwithstanding the described potential limitations, the FITT-STEMI study, a meticulously organized prospective registry with >20000 STEMI patients, seems to provide valuable practice-guiding information, as pointed out in the accompanying editorial (Reperfusion delay in patients with high-risk ST-segment elevation myocardial infarction: every minute counts, much more than suspected), on the possibility to improve survival in patients with cardiogenic shock by reducing reperfusion delay. More specifically, according to the presented data, 1 out of 5 patients with STEMI and shock could be saved, if PCI was performed within 90 minutes of the first medical contact.

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