A 68-year-old man is hospitalized after coronary artery bypass grafting surgery. The patient has a history of coronary artery disease treated with stenting of the right coronary artery several years ago. Medical history also includes hypertension, type 2 diabetes mellitus, and hypercholesterolemia. Over the past 6 months, the patient has had worsening angina, and cardiac catheterization revealed 80% stenosis of the left main artery and restenosis of the right coronary artery. Echocardiography showed a left ventricular ejection fraction of 40% with no valvular abnormalities. A 2-vessel coronary artery bypass grafting with a left internal mammary to the left anterior descending artery and a saphenous vein graft to the right coronary artery was performed. The intraoperative course was uncomplicated, and the patient was extubated 24 hours later. On the third postoperative day, the patient developed atrial fibrillation. He is hemodynamically stable with adequate urine output and good control of the postoperative pain. Serum electrolytes are within normal limits. The patient becomes concerned about the postoperative arrhythmia. Which of the following is the most accurate statement about this patient's atrial fibrillation?

Question

A 68-year-old man is hospitalized after coronary artery bypass grafting surgery.  The patient has a history of coronary artery disease treated with stenting of the right coronary artery several years ago.  Medical history also includes hypertension, type 2 diabetes mellitus, and hypercholesterolemia.  Over the past 6 months, the patient has had worsening angina, and cardiac catheterization revealed 80% stenosis of the left main artery and restenosis of the right coronary artery.  Echocardiography showed a left ventricular ejection fraction of 40% with no valvular abnormalities.  A 2-vessel coronary artery bypass grafting with a left internal mammary to the left anterior descending artery and a saphenous vein graft to the right coronary artery was performed.  The intraoperative course was uncomplicated, and the patient was extubated 24 hours later.  On the third postoperative day, the patient developed atrial fibrillation.  He is hemodynamically stable with adequate urine output and good control of the postoperative pain.  Serum electrolytes are within normal limits.  The patient becomes concerned about the postoperative arrhythmia.  Which of the following is the most accurate statement about this patient's atrial fibrillation?

Quizplus · Accepted Answer

Explanation: 11ec2b69_be15_c24d_8f63_6128f961b3c9_MD0005_00 Atrial fibrillation is a common postoperative complication of cardiac surgery. Patients with risk factors for underlying substrate that encourages atrial fibrillation (eg, advanced age, hypertension, left ventricular dysfunction) are at greatest risk of developing postoperative atrial fibrillation (POAF). Cardiac surgery likely provides transient encouragement of atrial fibrillation via a further increase in underlying substrate (eg, surgery-related atrial myocardial inflammation) and an increased rate of triggers resulting from a surgery-related increase in sympathetic tone. Most patients with no history of atrial fibrillation who develop POAF following cardiac surgery will spontaneously convertto sinus rhythm within a few days. However, such conversion to sinus rhythm does not signify resolution of atrial fibrillation and freedom from its associated complications. The development of POAF likely indicates substantial underlying substrate, and many patients will have recurrent episodes of atrial fibrillation (ie, paroxysmal disease) both during hospitalization and following discharge, placing them at risk for complications, including embolic stroke and heart failure (Choice E). POAF is also associated with increased long-term mortality. (Choice A) Myocardial reperfusion commonly precipitates an accelerated idioventricular rhythm, which appears similar on ECG to ventricular tachycardia but with a ventricular rate <100/min. Reperfusion is not a precipitant of atrial fibrillation. (Choice B) Acute ischemia is not a common or direct trigger of atrial fibrillation. Myocardial infarction (MI) can sometimes precipitate atrial fibrillation via increased sympathetic tone or abrupt onset left ventricular failure with atrial stretching; however, MI is unlikely in this patient in the absence of chest pain. (Choice C) Spontaneous conversion to sinus rhythm is typical of POAF, and the risk of recurrence is high. Cardioversion, either pharmacologic or electrical, is not indicated and is unlikely to be successful because affected patients usually have significant underlying substrate for atrial fibrillation, making sustained maintenance of sinus rhythm difficult. Educational objective: Postoperative atrial fibrillation (POAF) is common following cardiac surgery. Most patients spontaneously convert to sinus rhythm within a few days; however, the occurrence of POAF likely indicates significant underlying substrate for atrial fibrillation with ongoing risk for recurrence and complications (eg, stroke, heart failure). References: An update on the prognosis of patients with atrial fibrillation. (http://www.ncbi.nlm.nih.gov/pubmed/22949543) New onset atrial fibrillation predicts long-term mortality after coronary artery bypass graft. (http://www.ncbi.nlm.nih.gov/pubmed/20338499)

A 68-Year-Old Man Is Hospitalized After Coronary Artery Bypass Grafting