Non-traumatic chest pain is a frequent reason for an urgent ambulance visit of a patient by the emergency medical services (EMS). Chest pain (or chest pain-equivalent symptoms) can be innocent, but it can also signal an acute form of severe pathology that may require prompt intervention. One of these pathologies is cardiac ischemia, resulting from a disbalance between blood supply and demand. One cause of a diminished blood supply to the heart is acute coronary syndrome (ACS, i.e., cardiac ischemia caused by a reduced blood supply to myocardial tissue due to plaque instability and thrombus formation in a coronary artery). ACS is dangerous due to the unpredictable process that drives the supply problem and the high chance of fast hemodynamic deterioration (i.e., cardiogenic shock, ventricular fibrillation). This is why an ECG is made at first medical contact in most chest pain patients to include or exclude ischemia as the cause of their complaints.

For speedy and adequate triaging and treatment, immediate assessment of this prehospital ECG is necessary, still during the ambulance ride. Human diagnostic efforts supported by automated interpretation algorithms seek to answer questions regarding the urgency level, the decision if and towards which healthcare facility the patient should be transported, and the indicated acute treatment and further diagnostics after arrival in the healthcare facility. In the case of an ACS, a catheter intervention room may be activated during the ambulance ride to facilitate the earliest possible in-hospital treatment.

Prehospital ECG assessment and the subsequent triaging decisions are complex because chest pain is not uniquely associated with ACS. The differential diagnosis includes other cardiac, pulmonary, vascular, gastrointestinal, orthopedic, and psychological conditions. Some of these conditions may also involve ECG abnormalities. In practice, only a limited fraction (order of magnitude 10%) of the patients who are urgently transported to the hospital because of chest pain are ACS patients. Given the relatively low prevalence of ACS in this patient mix, the specificity of the diagnostic ECG algorithms should be relatively high to prevent overtreatment and overflow of intervention facilities. On the other hand, only a sufficiently high sensitivity warrants adequate therapy when needed.

Here, we review how the prehospital ECG can contribute to identifying the presence of myocardial ischemia in chest pain patients. We discuss the various mechanisms of myocardial ischemia and infarction, the typical patient mix of chest pain patients, the shortcomings of the ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) ECG criteria to detect a completely occluded culprit artery, the OMI ECG criteria (including the STEMI-equivalent ECG patterns) in detecting completely occluded culprit arteries, and the promise of neural networks in recognizing ECG patterns that represent complete occlusions. We also discuss the relevance of detecting any ACS/ischemia, not necessarily caused by a total occlusion, in the prehospital ECG.

In addition, we discuss how serial prehospital ECGs can contribute to ischemia diagnosis. Finally, we discuss the diagnostic contribution of a serial comparison of the prehospital ECG with a previously made nonischemic ECG of the patient.

非创伤性胸痛是紧急医疗服务 (EMS) 紧急救护车就诊患者的常见原因。胸痛（或类似胸痛的症状）可能是无害的，但也可能预示着严重病理的急性形式，可能需要立即干预。其中一种病理是心脏缺血，这是由于血液供应和需求之间的不平衡造成的。心脏血液供应减少的原因之一是急性冠状动脉综合征（ACS，即由于冠状动脉中血栓形成ACS 是危险的，因为不可预测的过程会导致供应问题，并且血流动力学快速恶化（即心源性休克、心室颤动）的可能性很高。这就是为什么大多数胸痛患者在第一次就医时都会进行心电图检查，以包括或排除缺血作为其主诉原因。

为了快速、充分的分诊和治疗，有必要在救护车乘坐过程中立即评估院前心电图。自动解释算法支持的人类诊断工作旨在回答有关紧急程度、是否应将患者运送到哪个医疗机构以及患者到达医疗机构后指示的急性治疗和进一步诊断的决定等问题。对于 ACS，可能会在救护车乘坐过程中启动导管介入室，以便尽早进行院内治疗。

院前心电图评估和随后的分诊决策非常复杂，因为胸痛并非唯一与 ACS 相关。鉴别诊断包括其他心脏、肺部、血管、胃肠道、骨科和心理疾病。其中一些情况还可能涉及心电图异常。实际上，因胸痛被紧急送往医院的患者中只有一小部分（数量级为 10%）是 ACS 患者。鉴于该患者群体中 ACS 的患病率相对较低，诊断心电图算法的特异性应该相对较高，以防止过度治疗和干预设施溢出。另一方面，只有足够高的敏感性才能保证在需要时进行充分的治疗。

在这里，我们回顾一下院前心电图如何有助于识别胸痛患者是否存在心肌缺血。我们讨论了心肌缺血和梗死的各种机制、胸痛患者的典型患者组合、ST段抬高型心肌梗死（STEMI）和非ST段抬高型心肌梗死（NSTEMI）心电图标准检测完全闭塞的缺点。罪魁祸首动脉、检测完全闭塞罪魁祸首动脉的 OMI 心电图标准（包括 STEMI 等效心电图模式），以及神经网络在识别代表完全闭塞的心电图模式方面的前景。我们还讨论了在院前心电图中检测任何 ACS/缺血（不一定由完全闭塞引起）的相关性。

此外，我们还讨论了院前连续心电图如何有助于缺血诊断。最后，我们讨论了院前心电图与患者先前进行的非缺血心电图的系列比较的诊断贡献。