Interventional cardiology

Pre-hospital cardiologist input on STEMI avoids cath lab activation

Cardiologists can remotely identify STEMI in 97% of cases by examining pre-hospital ECGs to avoid unnecessary catheter lab activations, Australian research has shown.

The findings come from real-world data collected at Liverpool Hospital in Sydney, where cardiologists have been using pre-hospital ECGs in remote consultations with paramedics to make decisions on cardiac catheter laboratory activation.

Under the system, paramedics acquire ECGs from patients with chest pain symptoms using monitors/defibrillators equipped with the University of Glasgow algorithm (UGA), sending the results directly to the on-call interventional cardiologist.

The transmitted ECGs come with a call-back number for the paramedic, enabling the cardiologist to conduct a remote consultation to discuss whether to activate the CCL.

Researchers analysed the outcomes of more than 1,000 such consultations between June 2010 and October 2016, some 52% of which ended with the cardiologist deciding on prehospital CCL activation.

They found 97% of decisions to activate were appropriate, based on STEMI ECG criteria of persistent (≥20 min) ST‐segment elevation of ≥1 mm (except ≥2 mm in men >40 years, ≥2.5 mm in men <40 years, or ≥1.5 mm in women in leads V2‐3) in ≥2 contiguous leads.

Almost the same percentage (96%) of decisions not to activate were also borne out, with the patients not meeting those same criteria, the researchers said.

Using the University of Glasgow algorithm alone would have almost doubled cath lab activations, the researchers said.

Reasons for appropriate CCL nonactivation included nondiagnostic ST‐segment elevation (25%), bundle branch block (26%), repolarisation abnormality (12%), artefact (14%), no ischaemic symptoms (6%) and others.

“The benefits of remote cardiologist consultation were identifying STEMI mimics and avoiding unnecessary CCL activations,” the researchers noted in Catheterization & Cardiovascular Interventions.

They added: “We believe the involvement of clinicians trained in ECG interpretation, regardless of speciality, would improve the efficiency of computer‐based PH‐ECG interpretation primarily by detecting ‘masquerading STEMI, provided that the process does not negatively impact reperfusion times.”

Ambulance ramping linked with increased mortality risk

It comes as separate research found longer ambulance offload times were associated with greater 30-day risks of death and ambulance re-attendance in patients with non-traumatic chest pain.

Troublingly, the Victorian study also found median offload times had increased over the study period, rising from 21 minutes in 2015 to 24 minutes during the first half of 2019.

Of the roughly 210,000 patients in the study, one-third waited longer than 28 minutes.

This group had a higher risk of death in the next 30 days compared to the third of patients who had a wait time of under 17 minutes (adjusted rates 1.57% vs 1.29%), the researchers reported in the MJA.

They also had a greater risk of a second ambulance attendance with chest pain (adjusted rates, 9.03% vs 8.15%). The figures excluded patients with STEMI and those transferred between hospitals.

Led by cardiologist Dr Luke Dawson, the researchers noted ambulance ramping had been associated with longer ED and hospital admission times overall.

“Our findings should alert clinicians and health policymakers to the need for innovative strategies that reduce ambulance offload times,” the authors said.

They called for Victorian hospitals to be issued performance targets with the aim of completing transfers within 15-20 minutes.

“Improving the speed of ambulance-to-ED transfers is urgently required,” they added.

“Such a change to guidelines would be consistent with other jurisdictions, such as the United Kingdom, where the National Health Service requires handover of patients within 15 minutes of an ambulance arriving at an ED.”

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