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3% rise in deaths for every 10 min delay in restoring blood flow after heart attack

Step up efforts to shorten time to treatment and improve outcomes, urge experts

Caroline White

Wednesday, 14 February 2018

The risk of death rises by 3% for every 10-minute delay in restoring blood flow after a major (STEMI) heart attack, finds research* published today in the European Heart Journal.

The numbers of deaths rise steadily and rapidly, the longer the period of time between patients’ first contact with a medical professional and treatment with percutaneous coronary intervention (PCI) to widen blocked arteries and restore blood flow to the heart, the findings show.

Up to now, most clinical research has focused on 'door to balloon time' —how long it takes for a patient to receive PCI after they arrive at a hospital.

And it’s not been clear what the impact on survival of the length of time from first medical contact (usually the emergency medical services) to balloon insertion for patients with ST-segment elevation myocardial infarction (STEMI) in unstable clinical conditions is.

The researchers therefore looked at how long it took 12,675 patients with STEMI who used emergency medical services to get to hospital and be given treatment with PCI in 48 German hospitals between 2006 and 2015.

Their analysis shows that for STEMI patients who have cardiogenic shock when the heart suddenly can’t pump enough blood to meet the body’s needs, every 10-minute delay in treatment is associated with an extra 3.3 deaths per 100 treated with PCI.

Death rates among the STEMI patients were 3% in those with a stable condition, 16% in those who had an out-of-hospital cardiac arrest but were stable, 39% in patients with cardiogenic shock, and 45% in patients who had an out-of-hospital cardiac arrest and cardiogenic shock.

But the number of deaths rose steeply the longer it took for patients to receive PCI, prompting them to conclude that one death in every 12 could be prevented if PCI was performed within the recommended time of less than 90 minutes.

A fifth of all patients given PCI between 150 to 180 minutes after their first contact with a medical professional died.

Lead author Professor Karl Heinrich Scholz, head of the Department of Cardiology at St Bernward Hospital at Hildesheim, said: “The most important finding of our study is that STEMI patients presenting with cardiogenic shock are more likely to survive if they receive rapid percutaneous coronary intervention.

“In this high-risk patient group, every 10-minute treatment delay was accompanied by 3.3 additional deaths, and this treatment-delay-related increase in mortality was ten-fold higher as compared to STEMI patients presenting with more stable conditions.

“This means that, especially in shock patients and in patients with cardiac arrest, maximum efforts are necessary to optimise processes of care to shorten the time to treatment and improve their outcome.”

In a linked editorial**, Professor William Wijns of the Lambe Institute for Translational Medicine and Curam at the National University of Ireland, and Professor Christoph Naber of University Hospital Essen, write: “The importance of this work cannot be overemphasised…..The present data demonstrate that time matters even more than we used to think…The present data call for immediate action….Reducing treatment delays as much as possible in all, but especially in patients with CS [cardiogenic shock] and/or OHCA [out-of-hospital cardiac arrest], should be our immediate next objective.”

When the emergency medical services (EMS) are called out to a patient with a suspected heart attack in Germany, a doctor trained in emergency medicine accompanies them. This facilitates prompt diagnosis and enables the doctor to call ahead to the nearest hospital with an on-call PCI team so that they can be ready to treat the patient the moment he or she arrives.

This approach can save more than 15 minutes in time to treatment. Bypassing the emergency department and going straight to the PCI team saved an average of 33 minutes in this study.

Not all European countries have this system, but regardless of what transportation system is used, Professor Scholz says the results of the study apply everywhere.

“Our results clearly indicate that, in patients with acute STEMI, the time from first medical contact to restoring blood flow via balloon insertion is a strong predictor of survival. Any effort to shorten this time interval is beneficial for STEMI patients.

“Maximum efforts are needed to shorten the time from first medical contact to balloon insertion in all STEMI patients, especially in those presenting with shock.

“To this end, it is important to avoid transportation of STEMI patients to unsuitable hospitals without PCI capability, and to circumvent admission to emergency departments or intensive care units, which will all delay the time to PCI treatment,” he emphasises.

*Scholz K, Maier S, Maier L, et al. 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, multicentre FITT-STEMI trial. European Heart Journal, ehy004, doi: 10.1093/eurheartj/ehy004.

**Wijns W and Naber C. Reperfusion delay in patients with high-risk ST-segment elevation myocardial infarction: every minute counts, much more than suspected. European Heart Journal. doi:10.1093/eurheartj/ehy069.

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