Diagnostic accuracy of a prehospital electrocardiogram rule-based algorithm for ST-elevation myocardial infarction: results from a population-wide project.

INTRODUCTION: This study reviewed the diagnostic accuracy of the prehospital electrocardiogram (PHECG) rule-based algorithm for ST-elevation myocardial infarction (STEMI) universally utilised in Hong Kong. METHODS: This prospective observational study was linked to a population-wide project. We analysed 2210 PHECGs performed on patients who presented to the emergency medical service (EMS) with chest pain from 1 October to 31 December 2021. The diagnostic accuracy of the adopted rulebased algorithm, the Hannover Electrocardiogram System, was evaluated using the adjudicated blinded rating by two investigators as the primary reference standard. Diagnostic accuracy was also evaluated using the attending emergency physician's diagnosis and the diagnosis on hospital discharge as secondary reference standards. RESULTS: The prevalence of STEMI was 5.1% (95% confidence interval [CI]=4.2%-6.1%). Using the adjudicated blinded rating by investigators as the reference standard, the rule-based PHECG algorithm had a sensitivity of 94.6% (95% CI=88.2%-97.8%), specificity of 87.9% (95% CI=86.4%-89.2%), positive predictive value of 29.4% (95% CI=24.8%-34.4%), and negative predictive value of 99.7% (95% CI=99.3%-99.9%) [all P<0.05]. CONCLUSION: The rule-based PHECG algorithm that is widely used in Hong Kong demonstrated high sensitivity and fair specificity for the diagnosis of STEMI.

Prehospital electrocardiogram shortens ischaemic time in patients with ST-segment elevation myocardial infarction.

INTRODUCTION: Total ischaemic time should be shortened as much as possible in patients with ST-segment elevation myocardial infarction (STEMI). This study evaluated whether prehospital 12-lead electrocardiogram (ECG) could shorten system delay in STEMI management. METHODS: From November 2015 to November 2017, 15 ambulances equipped with X Series Monitor/ Defibrillator (Zoll Medical Corporation) were used in the catchment area of Queen Mary Hospital, Hong Kong. Prehospital ECG was performed for patients with chest pain; the data were tele-transmitted to attending emergency physicians at the Accident and Emergency Department (AED) for rapid assessment. Data from patients with STEMI who were transported by these 15 ambulances were compared with data from patients with STEMI who were transported by ambulances without prehospital ECG or who used self-arranged transport. RESULTS: Data were analysed from 197 patients with STEMI. The median patient delay for activation of the emergency response system was 90 minutes; 12% of patients experienced a delay of >12 hours. There was a significant difference in delay between patients transported by ambulance and those who used self-arranged transport (P<0.001). For system delay, the use of prehospital ECG shortened the median time from ambulance on scene to first ECG (P<0.001). When performed upon ambulance on scene, prehospital ECG was available 5 minutes earlier than if performed in ambulance compartment before departure. Use of prehospital ECG significantly shortened AED door-to-triage time, AED door-to-first AED ECG time, AED door-to-physician consultation time, and length of stay in the AED (P<0.001 for all comparisons). CONCLUSION: Prehospital ECG shortened ischaemic time prior to hospital admission.

Two cases of severe intoxication associated with analytically confirmed use of the novel psychoactive substances 25B-NBOMe and 25C-NBOMe.

CONTEXT: A new group of novel psychoactive substance, the N-methoxybenzyl (NBOMe) derivatives of substituted phenethylamine, has recently emerged on the drug market, among which 25I-NBOMe and 25B-NBOMe have previously been implicated in clinical intoxications and fatalities. We report two cases of acute intoxication associated with these substances. CASE DETAILS: Two male patients (17 and 31 years of age) had ingested drugs labelled as 'NBOMe' or 'Holland film' and developed confusion, agitation, hypertension, tachycardia, hyperthermia, sweating and dilated pupils. Other features included convulsion, rhabdomyolysis and deranged liver function. The patients required benzodiazepines and other drugs for the control of symptoms. Urine samples from both patients were analysed using liquid-chromatography tandem mass spectrometry (LC-MS/MS) following glucuronidase digestion and solid-phase extraction. Identification was based upon comparison of the retention time and enhanced product ion scan with reference standards. In both urine samples, 25B-NBOMe was detected. Additionally, 25C-NBOMe was identified in one of the urine samples. DISCUSSION: The NBOMe compounds are highly potent 5HT2A receptor agonists and are also agonists at alpha-adrenergic receptors, which likely account for their serotonergic and sympathomimetic symptoms. The clinical testing of NBOMe drugs is not commonly available. Clinicians as well as laboratory staff play an important role in facilitating the detection of this group of potentially dangerous emerging drugs.