Interventional cardiology

Prehospital cath lab activation a win for early STEMI treatment

Prehospital activation of an acute STEMI code by paramedics reduces the door-to-balloon time by almost half (47%) compared to patients where the STEMI is activated in the ED, Australian figures show.

And the early revascularisation benefit does not come at the expense of unnecessary activation of the cardiac catheterisation laboratory due to false positive diagnoses.

A retrospective observational study of STEMI patients who received primary PCI (PPCI) in Perth during 2015 to 2018 has found the median door-to-balloon time (D2BT) was 40 minutes with prehospital STEMI activation versus 86 minutes in the ED activation group (p <0.00001).

In WA, the prehospital STEMI code is activated by the emergency physician after remote review of ECG and other clinical information supplied by paramedics.

The study, published in Heart, Lung and Circulation, found both D2BTs were within the international guidelines of 90 minutes.

However patients requiring an inter-hospital transfer (IHT) from a non-primary PCI capable metropolitan hospital to a PPCI capable hospital had a mean D2BT of 108 minutes.

“The percentage of patients receiving revascularisation within 90 minutes of door time was 98% in the PH group compared to 54% in the ED activation and 26% in IHT groups,” the study said.

The investigators said transfer from non-PPCI capable hospitals was a well-recognised factor in delaying urgent revascularisation.

“Likely causes for the delay in revascularisation in this group are logistics of transit between referral hospital to the PPCI centre and the time taken for clinical assessment at the referral centre.”

Pre-hospital activation also led to a 63% reduction in total ischaemia time – from onset of chest pain to first balloon inflation (CP2BT) – of 138 minutes compared to 220 minutes in ED activation and 221 minutes in the IHT group.

“The false positive STEMI activation rate was significantly higher amongst ED activation group (5.4%) compared to PH activation (2.75%), p-value 0.0115.”

“A detailed review of clinical practice in these referring centres is needed to analyse the benefits of thrombolysis over transfer for PPCI in selected patients.”

Lead investigator Dr Muhammad Shoaib, from the department of cardiology at Sir Charles Gairdner Hospital, told the limbic their results confirmed international studies.

“It shows that prehospital activation does save time and most people get earlier treatment. But this is only true if the patients are coming from the community – picked up by ambulances and brought to a major hospital.”

“If a patient goes to a smaller hospital that does not have a lab, and gets assessed and diagnosed there and then transferred, there are logistical delays which are quite significant. Those patients do not get early treatment even if they are called a STEMI before arriving in a major hospital,” he added.

Dr Shaoib said the situation required further evaluation of whether or not secondary metropolitan hospitals without 24/7 cardiac labs should be transferring patients to major metropolitan hospitals or utilising their own resources and offering a different treatment option.

Senior investigator Professor Brendan McQuillan told the limbic it was pleasing to demonstrate the clear benefits to patients from an efficient system of care.

“Our ongoing focus is to minimise delays in presentation, recognition, and transfer of STEMI patients to PCI capable hospitals”

Professor McQuillan, Director of Echocardiography at Sir Charles Gairdner Hospital and Dean of Medicine at UWA, said however that delays in recognition of STEMI and the initiation of appropriate medical care, including primary PCI, can occur.

“This study is not designed to assess the relative value of thrombolysis versus primary PCI in the management of STEMI,” he said.

The study authors noted that the use of standardised terminology and data recording processes was needed for accurate assessment of state-wide STEMI processes.

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