Heart failure can be categorized multiple ways. One of the most common ways is to classify systolic versus diastolic dysfunction. Approximately half of patients presenting with symptoms of CHF exhibit a near normal systolic function but have impaired diastolic function. Having diastolic dysfunction is categorized by failure of relaxation or filling of the ventricles. Systolic heart failure generally refers to depressed systolic function with an ejection function (EF) of less than 50%. Both typically cause clinical characteristics of congestive heart failure (CHF) including dyspnea, peripheral edema, pulmonary edema, orthopnea and paroxysmal nocturnal dyspnea. It is thought that having only diastolic dysfunction is associated with a better prognosis. Typically, an echocardiogram will show increased ventricular hypertrophy with diastolic failure and dilated ventricles with systolic failure however this is not always the case. Common etiologies for systolic heart failure include ischemia (most common cause), myocardial fibrosis, myocarditis, arrhythmias, and valvular heart disease. However, up to 20-30% of systolic heart failure cases have no clear inciting event. These typically include the cardiomyopathies (either dilated, non-ischemic, post-infectious, toxin-related). Less common causes include processes that increase preload including renal failure, liver failure, or lymphatic obstruction. Diastolic dysfunction typically is caused by concentric left ventricular hypertrophy (the most common cause), which almost always develops from increased afterload. Other typical causes include infiltration of the heart muscle with amyloid, iron, and glycogen or hypertrophic cardiomyopathy. Pericardial constriction and cardiac tamponade can also lead to acute diastolic dysfunction. Other common conditions that may present clinically like CHF include: circulatory congestion secondary to abnormal salt and water retention without cardiac involvement (renal failure) or non-cardiac causes of pulmonary edema (acute respiratory distress syndrome). Helpful tests to differentiate if cardiac origin include: Cardiac imaging (echocardiography), biomarker (BMP), pulmonary function tests, and chest x-ray.