Hypertrophic obstructive cardiomyopathy (HOCM) is an obstructive subvariety of hypertrophic cardiomyopathy. In hypertrophic cardiomyopathy, the left ventricular wall of the heart is abnormally thick, and the left ventricular cavity is small. HOCM is characterized by an excessively thick interventricular septum, which obstructs left ventricular outflow during ventricular systole. Pericardial tamponade is a potential complication after insertion of a pacemaker and can severely worsen obstruction of left ventricular outflow in patients with HOCM. In this article, we present a case study illustrating the cascade of complications that can occur after insertion of a pacemaker in a patient with HOCM and review the pathophysiology of this cardiac abnormality.