24-hour Holter ECG is one of the important and non-invasive investigations for patients having palpitation or syncope.

Compared with conventional ECG, Holter 24-hour ECG can continously record ECG signals up to 100,000 times in or even more than 24 hours if clinically indicated. This prolonged recording process is more likely to pick out episodic arrhythmias and transient myocardial ischemia, which are often missed by a resting ECG.