WBR0456

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 30-year-old athletic man is brought to the emergency department in cardiac arrest. The family informs the physician that multiple members of the family died at a young age. Despite resuscitation attempts, the patient is declared dead. During autopsy, the pathologist explains that the patient had a disarray of myocyte organization due to a mutation of the sarcomere gene. Which of the following is the most likely cause of death in this patient?]]
Answer A	AnswerA::Arrhythmia
Answer A Explanation	AnswerAExp::Patients with HOCM die at young age due to ventricular fibrillation, a fatal arrhythmia.
Answer B	AnswerB::Myocardial infarction
Answer B Explanation	[[AnswerBExp::Patients with HOCM do not usually die from myocardial infarction. The disease is caused by atherosclerotic plaques that occlude coronary arteries. Typically, myocardial infarction is a common cause of death in patients of older age groups with cardiovascular risk factors, such as diabetes mellitus, hypertension, smoking, and hyperlipidemia. Myocardial infarction at young age, however, can be seen in patients with homozygous familial hypercholesterolemia (FH), an autosomal dominant disorder caused by absent LDL receptors on hepatocytes.]]
Answer C	AnswerC::Cardiac tamponade
Answer C Explanation	[[AnswerCExp::Cardiac tamponade is a pericardial disease characterized by pericardial effusion that is large enough to cause constrictive force on cardiac chambers, eventually equalizing the pressures in all cardia chambers. Cardiac tamponade is characterized by chest pain that is relieved when sitting forward, hypotension, jugular venous distension, and pulsus paradoxus.]]
Answer D	AnswerD::Myocarditis
Answer D Explanation	AnswerDExp::Myocarditis is an inflammatory cardiomyopathy that could be of infectious or non-infectious causes. Most cases of myocarditis are in fact of viral origin due to coxsackie B virus.
Answer E	AnswerE::Stroke
Answer E Explanation	AnswerEExp::Stroke is not a common cause of death in young patients. Patients with atrial fibrillation are mostly at risk of stroke.
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient in this scenario has a histologic and genetic evidence of hypertrophic obstructive cardiomyopathy (HOCM). HOCM is an autosomal dominant disorder to a sarcomere mutation that most commonly affects the beta-myosin heavy chains. Other mutations are also described; they may affect the alpha-tropomyosin, or cardiac troponin T. Mutations of the sarcomere cause a disarray of myocyte organization. HOCM is a relatively common inherited disease that is found in 1:500 in the general population and is the most common cause of sudden death in the young. Patients usually die of ventricular fibrillation, a fatal arrhythmia. However, most patients with HOCM have no disability and live a normal life span. Educational Objective: Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal dominant inherited disorder caused by a mutation of the sarcomere gene. It is a common cause of death in the young, including athletes. Patients with HOCM usually die from a fatal arrhythmia. References: Maron, BJ. Hypertrophic cardiomyopathy. J Am Med Assoc. 2002;287(10):1308-1320.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Hypertrophic obstructive cardiomyopathy, WBRKeyword::HOCM, WBRKeyword::Arrhythmia, WBRKeyword::Sarcomere, WBRKeyword::Autosomal dominant, WBRKeyword::Cardiac arrest, WBRKeyword::Sudden cardiac death
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