i heard there is still considerable risk of sudden cardiac death although my EKG/ECG as well as Echocardiogram as well as blood tests (cholestrol levels) look good. ....

...reason being plaque in coronary arteries can be high regardless of good results of above mentioned tests.

is it true? if so, how to early detect such risks ?

Do yourself a favour and stop worrying about what might happen.

If you're going to have a heart atack you'll have one....plain and simple as that.

In the words of Jason Nevins vs Run DMC....It's like that, and that's the way it is