ECG Results
The ECG must be considered in the context of the history and physical examination. The discussion above refers to the pivotal role of an ECG in the patient with a history of ischaemic cardiac chest pain. However, the ECG will also be useful in patients who have non-ischaemic pain (see Figure 1 and Table 10).
Normal ECG
A normal ECG significantly reduces the probability of AMI [4,5]. It does not, however, reduce this probability enough to allow confident safe discharge based upon the history and ECG alone [2].
Therefore, patients who present with chest pain in whom cardiac ischaemia is suspected and who have a normal ECG should undergo further diagnostic testing (i.e. delayed cardiac markers, exercise testing, etc.) before they can be confidently ascribed to a low risk group.
Table 10: ECG findings associated with non-ischaemic chest pain conditions(4,6)
| ECG finding | Context | Diagnosis | |||
|---|---|---|---|---|---|
| Diffuse concave-upward ST segment elevation | Positional pain Pericardial rub |
Pericarditis | |||
| Right ventricular strain Pattern | Pleuritic pain Hypoxia Pleural rub |
Pulmonary embolus | |||
| Diffuse ST/T wave changes | Atypical pain Heart failure |
Myocarditis | |||
| Inferior ST elevation Normal (30%) LVH (26%) |
Tearing chest pain Radiation to back Differential pulses Differential blood pressures New diastolic murmur |
Aortic dissection | |||
Learning Bite
A normal ECG in a patient with chest pain does not allow safe discharge without further investigation.