A 61-year-old man comes to the office for follow-up for coronary artery disease. He says that he feels "fine." The patient has had no chest pain, syncope, or lower extremity swelling. He has had some shortness of breath on moderate exertion. Medical follow-up has been inconsistent, and he has missed multiple medical appointments. Medical history includes a myocardial infarction 2 years ago. The patient is an ex-smoker with a 20-pack-year smoking history. Blood pressure is 122/70 mm Hg, and pulse is 70/min and regular. Echocardiogram reveals left ventricular dilation, apical left ventricular aneurysm, and ejection fraction of 23%. There are no significant valvular abnormalities. Appropriate pharmacotherapy is prescribed, medical compliance is reinforced, and a follow-up appointment is scheduled. Several days later, the patient suddenly dies at home. Which of the following is the most likely cause of death in this patient?

Question

A 61-year-old man comes to the office for follow-up for coronary artery disease.  He says that he feels "fine."  The patient has had no chest pain, syncope, or lower extremity swelling.  He has had some shortness of breath on moderate exertion.  Medical follow-up has been inconsistent, and he has missed multiple medical appointments.  Medical history includes a myocardial infarction 2 years ago.  The patient is an ex-smoker with a 20-pack-year smoking history.  Blood pressure is 122/70 mm Hg, and pulse is 70/min and regular.  Echocardiogram reveals left ventricular dilation, apical left ventricular aneurysm, and ejection fraction of 23%.  There are no significant valvular abnormalities.  Appropriate pharmacotherapy is prescribed, medical compliance is reinforced, and a follow-up appointment is scheduled.  Several days later, the patient suddenly dies at home.  Which of the following is the most likely cause of death in this patient?

Quizplus · Accepted Answer

The risk of sudden cardiac death (SCD) is increased in individuals with prior myocardial infarction (MI) complicated by left ventricular (LV) systolic dysfunction with ejection fraction ≤30%. The majority of SCD in this population results from ventricular arrhythmia, usually in the form of ventricular tachycardia degenerating to ventricular fibrillation. Following MI, patients should be placed on optimal medical therapy with a beta blocker (eg, metoprolol), an ACE inhibitor or angiotensin receptor blocker, and possibly a mineralocorticoid antagonist (eg, spironolactone). In many patients, any systolic dysfunction following MI will normalize or significantly improve with medical therapy, lowering the risk of SCD. However, in patients with persistent LV ejection fraction ≤30% despite optimal medical therapy, the risk of SCD remains high and primary prevention with placement of an implantable cardioverter-defibrillator (ICD) is indicated. (Choices A and B) Myocardial free wall rupture and papillary muscle rupture are mechanical complications of MI that typically occur within 5 days to 2 weeks or 3-5 days, respectively. Although the patient has an LV aneurysm on echocardiography, the risk of myocardial wall (or papillary muscle) rupture occurring 2 years after MI would be extremely low. If this patient experienced a repeat MI, it is unlikely for a mechanical complication to cause SCD without the patient first seeking care for chest pain; SCD during acute MI is also typically due to ventricular arrhythmia. (Choice C) Acute pulmonary embolism is a potential cause of SCD. However, ventricular arrhythmia is more likely in this patient with ischemic cardiomyopathy and severe LV systolic dysfunction. (Choice D) Sinus arrest can occur with sick sinus syndrome, which most commonly results from age-related degeneration of the sinoatrial node. However, it rarely leads to SCD because an escape rhythm is triggered in the atrioventricular junction, allowing for continued ventricular contraction at a low rate (eg, 45/min) to maintain some level of cardiac output. Educational objective: Patients with prior myocardial infarction complicated by left ventricular systolic dysfunction with ejection fraction ≤30% are at an increased risk of sudden cardiac death due to ventricular arrhythmia (ie, ventricular tachycardia, ventricular fibrillation). Following a trial of optimal medical therapy, primary prevention with placement of an implantable cardioverter-defibrillator is indicated in these patients. References: Device therapies in the post-myocardial infarction patient with left ventricular dysfunction. (http://www.ncbi.nlm.nih.gov/pubmed/18722189)

A 61-Year-Old Man Comes to the Office for Follow-Up for Coronary