Here's a quick recap of what an ECG can detect: Heart rhythm problems (arrhythmias): Such as atrial fibrillation, tachycardia, and bradycardia. Heart attacks (myocardial infarction): Both current and past heart attacks. Enlargement of the heart (hypertrophy): Which can be caused by high blood pressure or other conditions. Problems with the heart's structure: Such as congenital heart defects. Pericarditis: Inflammation of the sac surrounding the heart.