Valvar heart disease can be complicated by hemodynamic derangements, depending on the degree of the abnormality. Stenosis causes pressure overload of the chamber draining through the valve and regurgitation results in volume overload. Many lesions have a component of both, resulting in both pressure and volume overload. Increased wall stress causes myocardial stretching and fibrosis, resulting in scarring; a nidus for arrhythmia development. Arrhythmias can complicate the clinical picture and increase the morbidity and mortality in patients with both congenital and acquired valvar disease. In adults with congenital heart disease, arrhythmias are the most common cause of sudden death, followed by heart failure. Valvar stenosis and insufficiency certainly contribute to this. This article highlights the need for arrhythmia surveillance for high-risk valvar lesions.