This is the second of a 2-part review of heart failure in children. In Part I, we focused on history, definition, etiology, and pathophysiology.1 In Part II, we review diagnosis, treatment, and future directions. The intention is to highlight key concepts and trends, with the goal of stimulating further interest in research to support evidence-based treatment in pediatric cardiovascular disease. In Part I, we described heart failure as a progressive clinical and pathophysiological syndrome that results from a complex interplay among circulatory, neurohormonal, and molecular derangements. The diagnosis of heart failure in children is based on a combination of clinical signs and symptoms, with assessment of severity of cardiac status augmented by information obtained from laboratory findings such as exercise testing, noninvasive imaging, and biomarker profiling. In symptomatic children without known heart disease, a large part of the evaluation will involve identifying the underlying cardiac diagnosis. ### Symptoms The characteristic signs and symptoms of heart failure include growth failure, respiratory distress, and exercise intolerance and are present in children with heart failure regardless of the cause. Age-adjusted modifications of heart failure scores can quantify the symptoms of heart failure in children and have been used both as inclusion criteria and as end points in several studies of heart failure in children.2,3 Unfortunately, heart failure class at presentation is a poor predictor of worsening clinical outcome.4,5 The scenario of a child with few symptoms who suddenly develops decompensated heart failure is well known and highlights the limitations of heart failure class as a predictor or outcome in children. In patients with right heart dysfunction, as may occur in tetralogy of Fallot (TOF) or Ebstein anomaly, or in patients with single ventricle physiology, the predominant clinical findings are those of systemic venous congestion, decreased exercise capacity because of abnormal functioning of …