Can having conditions like splenomegaly or GERD cause left axis deviation on an ECG even if there aren't any other abnormalities? My cardiologist mentioned that having LAD in my case is normal since there aren't any additional issues, but I'm worried. Should I be concerned about this?

Your cardiologist's reassurance is important here. Left axis deviation (LAD) on an ECG can sometimes be a normal variant, especially if no other heart abnormalities are present.

Regarding your conditions:

1. Splenomegaly (enlarged spleen) typically does not cause changes in the heart's electrical axis seen on an ECG.
2. GERD (gastroesophageal reflux disease) also does not directly affect the heart's electrical conduction or cause LAD.

It's good that your cardiologist has evaluated your ECG in the context of your overall health and found no concerning issues. However, continue regular follow-ups as advised, and report any new symptoms like chest pain, palpitations, or shortness of breath.

In summary, based on current information, your splenomegaly and GERD are unlikely to be causing the LAD, and if no other heart problems are detected, this finding alone is usually not worrisome.