My heart starts pounding even when I am at rest, occasionally, what could it be ?

My heart starts pounding even when I am at rest, occasionally, what could it be ?

It could be simply that you are becoming anxious at that time or having a panic attack, both of which are not heart diseases. But sometimes it could also be due to an abnormal rhythm of the heart (cardiac arrhythmia). Many common arrhythmias like ventricular premature beats (premature beats originating from the lower chambers of the rather than from the sinus node situated in the right upper chamber of the heart) may not be harmful if they occur occasionally. Some rare forms of abnormal heart rhythms like a ventricular tachycardia (fast rhythm originating from the lower chambers of the heart) could be life threatening. An electrocardiogram recorded during the episode will often clarify the correct reason.