A 55-year-old man is brought to the emergency department due to severe substernal chest pain that is accompanied by sweating and mild dyspnea. The pain started as midline chest discomfort several hours ago but then progressively worsened such that the patient could not fall asleep. He received sublingual nitroglycerin in the ambulance without significant pain relief. His medical history includes hypertension, type 2 diabetes mellitus, and hyperlipidemia. ECG demonstrates normal sinus rhythm and ST-segment elevation in leads I, aVL, and V1-V4, with deep Q wave development over the next several hours. Cardiac catheterization in this patient would most likely show which of the following?

Question

A 55-year-old man is brought to the emergency department due to severe substernal chest pain that is accompanied by sweating and mild dyspnea.  The pain started as midline chest discomfort several hours ago but then progressively worsened such that the patient could not fall asleep.  He received sublingual nitroglycerin in the ambulance without significant pain relief.  His medical history includes hypertension, type 2 diabetes mellitus, and hyperlipidemia.  ECG demonstrates normal sinus rhythm and ST-segment elevation in leads I, aVL, and V1-V4, with deep Q wave development over the next several hours.  Cardiac catheterization in this patient would most likely show which of the following?

Quizplus · Accepted Answer

11ec160b_38d9_7764_9249_d7bfccd30ef8_MD0001_00 This patient with persistent substernal chest pain and ECG demonstrating ST elevation in the anterolateral leads has an ST-elevation myocardial infarction (STEMI). In the evolution of STEMI on ECG, peaked T waves in the affected leads are typically the first manifestation, followed by the appearance of ST elevation within several minutes, then Q waves within hours to days. Patients with STEMI typically have sudden-onset substernal chest pain that may be accompanied by nausea, diaphoresis, or dyspnea; the pain does not improve with rest or the administration of short-acting nitrates (eg, nitroglycerin). Myocardial infarction is usually caused by acute atherosclerotic plaque rupture with release of lipids, collagen, and tissue factor into the blood stream; because these contents are highly thrombogenic, there is rapid formation of overlying thrombus. In STEMI, the overlying thrombus is extensive enough to fully occlude the coronary artery lumen, completely blocking blood flow to a portion of the heart and leading to transmural (full-thickness) infarction of the myocardial wall. Partially obstructive thrombus (Choice E) is likely to produce non-STEMI or unstable angina. Non-STEMI is associated with impaired blood flow to only the subendocardial region; the symptomatic presentation is similar to STEMI, but ECG reveals ST segment and T wave abnormalities with no ST elevation. (Choice A) Atherosclerotic plaque obstructing 50% of the coronary artery lumen is likely to be asymptomatic. Symptoms of stable angina do not typically become prominent until >70% of the cross-sectional area of the coronary artery lumen is occluded. (Choice B) Atherosclerotic plaque obstructing 80% of the coronary artery lumen is likely to cause stable angina, characterized by substernal or left-sided chest pressure, tightness, or pain that is precipitated by exertion and relieved by rest or short-acting nitrates. (Choice D) Coronary artery vasospasm (vasospastic or Prinzmetal angina) results from hyperactivity of intimal smooth muscle, usually in the absence of significant atherosclerotic coronary artery disease. Transient anginal chest pain with corresponding ST elevation on ECG can occur; however, the chest pain should rapidly resolve with nitroglycerin. Educational objective: ST-elevation myocardial infarction involves transmural (full-thickness) infarction of the myocardial wall, and usually results from acute atherosclerotic plaque rupture with the development of overlying thrombus that fully occludes the coronary artery lumen. It classically presents with sudden-onset substernal chest pain that is not relieved by rest or short-acting nitrates. ECG demonstrates ST elevation in the affected leads with subsequent development of Q waves. __________ References: Atherosclerotic plaque rupture-pathologic basis of plaque stability and instability. (http://www.ncbi.nlm.nih.gov/pubmed/10341833)

A 55-Year-Old Man Is Brought to the Emergency Department Due