Abstract Sudden cardiac death (SCD) pathophysiological point of view can be either mechanical or electrical. In case of mechanical SCD, the most frequent causes are pulmonary thromboembolism and cardiac tamponade due to intrapericardial rupture (aortic dissection, heart rupture). This distinction is important because cardiac arrest retains survival potential through cardiopulmonary resuscitation and defibrillators only if the rhythm is shockable. The heart diseases that can cause SCD vary according to the age of the individual. In young people, primary electrical diseases (‘ion channel diseases’) and cardiomyopathies (particularly hypertrophic and arrhythmogenic), both genetically determined and therefore potentially recurred in the proband’s family, as well as myocarditis and coronary anomalies prevail; in adult–elderly populations, coronary atherosclerosis with its complications and degenerative valve diseases (aortic stenosis and mitral valve prolapse) predominate. In this short text, the main structural heart diseases characterized by electrical instability at risk of SCD will be recalled, with a focus on coronary, myocardial, and valvular diseases.