Hi, i'm a 29 year old guy, apparently healthy. in the last 6 months i have undergone 3 ecgs, 1 24h cardiac holter, 2 echocardiographies and 1 stress ecg. from all these tests, there was no evidence of cardiac channelopathies (long qt, brugada etc.?

You don't mention any symptoms. Why all these studies? Do you experience palpitations, recurrent chest pains,lightheadedness or fainting? Family history of unexplained sudden death? A 24 hour Holter monitor may not be long enough to shed any light on symptoms. Consider an implantable loop recorder if you still have concerns.

In case your symptoms are persisting, you may need a different test, your cardiologist should be able to coordinate, otherwise your test results are reassuring so far.