When nervous my apical pulse diameter is wider >3cm lying on left, when calm my apical pulse diameter becomes small <3cm. Why? Do I have cardiomegaly?

Inaccurate. The apical pulse suggests cardiomegaly by its displacement laterally, not by its size which is not predictive. Moreover, it's nothing more than a bedside screening procedure with notorious inaccuracy unless you're very experienced in its interpretation. If you're worried, get a chest xray (or an echocardiogram).

Related Questions