This chapter describes cardiac emergencies, including adult life support (basic and advanced), universal treatment algorithm, acute coronary syndrome (ACS), ST-elevation myocardial infarction (STEMI; diagnosis, general measures, reperfusion therapy, thrombolysis, reperfusion by primary percutaneous coronary intervention (PCI), surgery, predischarge risk stratification, complications), ventricular septal defect post-myocardial infarction (MI), atrial tachyarrhythmia post-MI, bradyarrhythmias and indications for pacing, hypotension and shock post-MI, cardiogenic shock, non-ST-elevation MI (NSTEMI; diagnosis, risk stratification, medical management, invasive and non-invasive strategies, discharge, and secondary prevention), arrhythmias, tachyarrhythmias, tachycardia (broad complex, monomorphic, polymorphic, ventricular, narrow complex), atrial fibrillation (AF), atrial flutter, multifocal atrial tachycardia (MAT), accessory pathway tachycardia, atriventricular nodal re-entry tachycardia (AVNRT), bradyarrhythmias, sinus bradycardia, intraventricular conduction disturbances, pulmonary oedema, endocarditis (infective, culture-negative, right-sided, prosthetic valve, prophylaxis), acute aortic regurgitation (AR), acute mitral regurgitation (MR), deep vein thrombosis (DVT), pulmonary embolism (PE), fat embolism, hypertensive emergencies, hypertensive encephalopathy, aortic dissection, acute pericarditis, bacterial pericarditis, cardiac tamponade, and congenital heart disease in adults.