Hypertrophic cardiomyopathy (HCM) is a common inherited disease occurring in about 1 of 500 births. Atrial fibrillation (AF) is the most commonly occurring tachyarrhythmia and often occurs in patients with structural heart disease. Thus, it is not surprising that AF occurs in about 25% of patients with HCM and is likely to occur due to changes in atrial histology including myocyte hypertrophy and disarray, interstitial fibrosis and left atrial dilatation secondary to left ventricular hypertrophy, outflow obstruction, and mitral regurgita-