Diversion of ST-elevation myocardial infarction patients for primary angioplasty based on wireless prehospital 12-lead electrocardiographic transmission directly to the cardiologist's handheld computer: a progress report

Abstract

Background

Time to reperfusion is critical for outcome in patients with ST-elevation myocardial infarction (STEMI). In our region, patients are routinely treated by primary percutaneous coronary intervention (pPCI), but rerouting patients from the primary receiving hospital to a catheterization center can cause unacceptable delays that may exceed 1 hour in the emergency department. Wireless transmission of prehospital electrocardiograms (ECGs) to receiving stations in hospitals has been shown to reduce time from symptom onset to reperfusion. However, transmission directly to a cardiologist's handheld digital device has not been investigated.

Aim

To report preliminary data from a larger ongoing trial evaluating prehospital 12-lead ECG transmission to a cardiologist's handheld device in patients with symptoms suggesting an acute coronary syndrome.

Method

Patients suffering acute, nontraumatic chest pain have their prehospital ECG transmitted by wireless technology directly to a cardiologist's handheld device at an invasive hospital, allowing diversion of STEMI cases to rapid pPCI. Transmission failures are documented. Times for symptom onset, 911 alert, ECG recording, hospital arrival, and pPCI are obtained. All time intervals are summarized as median values and are compared with historic controls from the Danish multicenter study, DANAMI-2.

Results

During the first 15 months of the trial, prehospital ECGs were transmitted for 408 chest pain patients with an overall success rate of 93%. Cardiologist receiving the ECGs recommended that 113 patients (28%) be diverted for pPCI. Mean time from symptom onset to 911 alert was 2 hours 16 minutes (range, 1 minute to 23 hours 15 minutes), and the ambulance response interval was 5 minutes (range, 1-25 minutes). The ambulance on-scene time had increased by 7 minutes compared with historic controls (P < .05). Time from ECG recording to hospital arrival was 25 minutes. The total prehospital time was 2 hours 57 minutes. The hospital treatment time was substantially reduced among diverted patients. Hospital arrival to procedure start was 40 minutes, compared with 94 minutes in the DANAMI-2 historic control group (P < .01).

Conclusion

These preliminary data suggest that transmission of prehospital 12-lead ECGs directly to the attending cardiologist using handheld devices is a technologically sound concept without major safety concerns and markedly reducing time to reperfusion in patients with STEMI.

Introduction

Every year, 12 000 patients are diagnosed with an acute myocardial infarction in Denmark. About 6000 have electrocardiographic (ECG) changes demonstrating ST-elevation myocardial infarction (STEMI). Since 1978, pharmacologic and mechanical reperfusion therapies have been commonly used in these patients [1], [2]. Both intravenous thrombolysis and percutaneous coronary intervention (PCI) have shown the best results when performed within the first few hours after onset of acute symptoms [3], [4], [5], [6]. As further time elapses, the benefits of these treatments quickly decline.

The Danish randomized trial on PCI versus thrombolytic therapy in patients with STEMI (DANAMI-2) [7] showed a 40% relative reduction in the composite primary end point of death, disabling stroke and reinfarction within 30 days (absolute reduction, 13.7%-8%; P = .0003) associated with primary PCI (pPCI). The results were provocative because patients were randomized up to 12 hours after symptom onset and with treatment delays up to 3 hours before pPCI. The delay was caused by the transportation time and delays of approximately 50 minutes at the referral hospitals before the start of transfer. This delay could have been prevented if the patients had been transported directly from site of the alarm/ambulance pickup to the invasive hospital.

To reduce time from symptom onset to optimal treatments in patients with acute coronary syndrome, various health organizations have used cellular transmission of ECGs to receiving stations in hospitals [8], [9]. However, ECG transmission directly to a consulting cardiologist's wireless hand-held digital device (mobile phone or pocket computer) with web browsing capabilities has only recently become an option [10]. The feasibility of transmitting 12-lead ECGs from the ambulance to an attending cardiologist for confirmation of the diagnosis of STEMI, with the consequence of redirecting the patient directly to an invasive hospital for pPCI, has not yet been investigated.

The aim of this report on preliminary data from a larger ongoing trial is to evaluate the safety and feasibility of prehospital 12-lead ECG transmission to a cardiologist's handheld device in patients with symptoms suggesting an acute coronary syndrome.