Despite its invaluable usefulness i

Despite its invaluable usefulness if used correctly, the interpretation of an ECG recording of normal appearance must be performed with caution. We should bear in mind that a relatively high percentage of patients with coronary heart disease, in the absence of chest pain, show a normal ECG recording. In approximately 5% to 10% of acute coronary syndromes (ACSs), the ECG is normal or borderline, especially in the early phases. Furthermore, the ECG may appear normal after amyocardial infarction (MI). Therefore, a normal ECG is not completely reassuring, because a patient may die from cardiac causes even on the same day a normal recording was taken. However, in the absence of any clinical symptoms or signs or family history of sudden death, the possibility of this occurring is very remote.