Unmasking of Occult Myasthenia Gravis in Hypertrophic Cardiomyopathy by Beta Blockers

Hypertrophic cardiomyopathy (HCM) is a genetic disorder that has a primarily autosomal dominant inheritance pattern, with variable penetrance and phenotypic expressivity [1]. Although its etiology has been linked to defects in various genes encoding for the sarcomeric proteins, association of HCM with immune linked disorders like myasthenia gravis is extremely rare. We report a case of obstructive HCM who when treated with beta blockers developed acute unmasking of latent myasthenia gravis, which was secondary to an underlying thymoma. The patient underwent successful resection of the thymic mass and made an uneventful recovery. Physicians need to be aware of such unusual associations to be able to manage these cases appropriately in clinical practice.