MKSAP quiz on atrial fibrillation

The following cases and commentary, which focus on atrial fibrillation, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP 18).

Case 1: Preoperative evaluation for colon resection

A 77-year-old woman is seen for a preoperative medical evaluation before resection of the sigmoid colon for recurrent diverticulitis scheduled 5 days from now. She has nonvalvular atrial fibrillation and is receiving long-term warfarin, without a history of bleeding complications. She has no history of stroke, transient ischemic attack, or intracardiac thrombus. History is also significant for hypertension. Medications are warfarin, chlorthalidone, and metoprolol.

The physical examination, including vital signs, is normal.

The INR measurement is 2.3. Calculated CHADS2 score is 2, and CHA2DS2-VASc score is 4.

In addition to withholding warfarin before surgery, which of the following is the most appropriate management of this patient's perioperative anticoagulation?

A. Begin aspirin, 81 mg/d
B. Begin enoxaparin when the INR drops below 2.0
C. Begin unfractionated heparin when the INR drops below 2.0
D. No additional interventions

View correct answer for Case 1

Case 2: Recent catheter ablation and progressive dyspnea

A 63-year-old man is evaluated in the emergency department for progressive dyspnea. The patient reports increasing difficulty breathing while lying flat. He has a history of atrial fibrillation and underwent catheter ablation 1 week ago. Medical history is otherwise significant for hypertension. He has no history of heart failure or left ventricular dysfunction. Medications are warfarin, dronedarone, and lisinopril.

On physical examination, temperature is normal, blood pressure is 88/72 mm Hg, pulse rate is 112/min, and respiration rate is 16/min. Pulsus paradoxus of 12 mm Hg is present. Oxygen saturation breathing ambient air is 96%. Cardiac examination reveals elevated estimated central venous pressure. Heart sounds are difficult to auscultate. Lung examination reveals no crackles.

An electrocardiogram demonstrates sinus tachycardia.

Which of the following is most likely responsible for the patient's symptoms?

A. Atrioesophageal fistula
B. Cardiac tamponade
C. Pulmonary vein stenosis
D. Retroperitoneal bleeding

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Case 3: Poststroke care

A 72-year-old woman is evaluated in the emergency department 5 hours after developing difficulty speaking and facial weakness on the right. She takes no medication.

On physical examination, vital signs are normal. The patient is awake and attentive. Spontaneous speech is slow. Right-sided facial weakness and dysarthria are noted.

Hemoglobin level, platelet count, and coagulation profile are within normal limits.

An electrocardiogram is normal. A CT scan of the head shows an acute left frontal ischemic stroke. A carotid duplex ultrasound reveals less than 40% stenosis in both internal carotid arteries; a transcranial Doppler ultrasound is normal. A transthoracic echocardiogram shows an ejection fraction of 50% but is otherwise unremarkable.

Aspirin and rosuvastatin are initiated, and the patient is admitted to the telemetry unit for 3 days, during which time she remains in sinus rhythm.

Which of the following is the most appropriate next step in management?

A. Addition of clopidogrel
B. Outpatient cardiac telemetry
C. Substitution of apixaban for aspirin
D. Transesophageal echocardiography

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Case 4: Discharge plan for heart failure exacerbation

A 52-year-old man is evaluated before discharge. Medical history is significant for atrial fibrillation and a 7-year history of heart failure with reduced ejection fraction. He was initially hospitalized for a 2-week history of increasing exertional dyspnea, peripheral edema, and a weight gain of 4.1 kg (9 lb). He had not been taking his medications for the past month. He underwent diuresis with a loss of 6.8 kg (15 lb), and he currently feels well. Medications are furosemide, digoxin, warfarin, and low doses of carvedilol and lisinopril.

On physical examination, vital signs are normal. Other than an irregularly irregular rhythm, cardiopulmonary examination is normal. There is no peripheral edema.

Which of the following is the most appropriate management?

A. Add ivabradine
B. Add spironolactone
C. Perform cardioversion
D. Schedule follow-up within 1 week

View correct answer for Case 4

Case 5: Dyspnea and palpitations

A 36-year-old man is evaluated for a 3-day history of progressive exertional dyspnea and palpitations. Medical history is notable for hypertrophic cardiomyopathy and mild mitral regurgitation. His only medication is metoprolol succinate.

On physical examination, pulse rate is 116/min and irregularly irregular. Oxygen saturation is 98% breathing ambient air. There is jugular venous distention. A grade 3/6 systolic crescendo-decrescendo murmur is heard along the left sternal border. The remainder of the examination is normal.

An electrocardiogram demonstrates atrial fibrillation with rapid ventricular response. Transesophageal echocardiogram shows asymmetric septal hypertrophy and dynamic left ventricular outflow tract obstruction, with a gradient of 36 mm Hg. There is no evidence of left atrial appendage thrombus.

His CHA2DS2-VASc score is 0 points.

In addition to acute anticoagulation with heparin, which of the following is most appropriate for thromboembolic risk reduction in this patient?

A. Dabigatran
B. Dose-adjusted warfarin
C. High-dose aspirin
D. No further therapy

View correct answer for Case 5

Answers and commentary

Case 1

Correct answer: D. No additional interventions.

The most appropriate management of this patient's preoperative anticoagulation is to withhold warfarin without bridging anticoagulation. Anticoagulant therapy increases the risk for perioperative hemorrhage and should be discontinued in most patients before surgery. Bridging anticoagulation is the administration of therapeutic doses of short-acting parenteral therapy, usually heparin, when anticoagulant therapy is being withheld during the perioperative period in patients with elevated thrombotic risk. This patient is undergoing a procedure associated with elevated bleeding risk, and she has no history of stroke, transient ischemic attack (TIA), or intracardiac thrombus. Therefore, the risks of bridging anticoagulation outweigh the thrombotic risk, and the warfarin should be withheld without bridging anticoagulation.

There is no role for aspirin in bridging anticoagulation. In patients with normal kidney function who require bridging anticoagulation, low-molecular-weight heparin is the agent of choice.

In 2019, the American Heart Association/American College of Cardiology/Heart Rhythm Society updated their 2014 guideline on the management of atrial fibrillation. For patients with atrial fibrillation without a mechanical heart valve, the updated guideline recommends that decisions about bridging therapy should balance the risk for stroke with the risk for bleeding. Bridging is typically reserved for patients at highest risk for thromboembolism. The 2018 American College of Chest Physicians guideline on antithrombotic therapy for atrial fibrillation recommends forgoing bridging in patients with atrial fibrillation on warfarin who do not have a mechanical valve and are otherwise not at high risk for thromboembolism. This patient has no additional risk factors for thromboembolism other than chronic atrial fibrillation, and perioperative bridging is not required.

Key Point

  • In patients on warfarin who are undergoing surgery, bridging anticoagulation is typically reserved for patients at highest risk for thromboembolism.

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Case 2

Correct answer: B. Cardiac tamponade.

The catheter ablation–related complication that is most likely responsible for the patient's symptoms is cardiac tamponade. Although cardiac tamponade occurs in approximately 1% of patients who undergo catheter ablation procedures for atrial fibrillation, it is the most common serious complication and is likely to result in death if not recognized and treated urgently. Cardiac tamponade occurs within a mean of 10 days after the procedure, although it may occur within hours of the procedure or be delayed by weeks. Cardiac tamponade should be suspected when the patient has a compatible history, hypotension, elevated jugular venous pressure, narrow pulse pressure, and pulsus paradoxus. An enlarged cardiac silhouette may be seen on chest radiograph (“water-bottle heart”). The electrocardiogram typically demonstrates sinus tachycardia and electrical alternans. Echocardiography readily detects pericardial effusions and is the primary modality for diagnosing cardiac tamponade.

Patients who develop an atrioesophageal fistula most commonly present 1 to 4 weeks after the ablation procedure. Patients may exhibit a sudden onset of neurologic symptoms from esophageal air embolization. Patients may also present with fever, chest pain, seizures, transient ischemic attack after food intake, hematemesis, and endocarditis. MRI and CT are preferred as diagnostic studies.

Patients who develop dyspnea months to years after atrial fibrillation ablation may have pulmonary vein stenosis. Other symptoms may include cough, chest pain, and hemoptysis. Pulmonary vein stenosis occurs in approximately 1% to 3% of patients, but intervention to relieve symptoms is required in only 10% of these patients. Guidelines recommend CT or MRI as the preferred diagnostic test in symptomatic patients.

Vascular events, including hematomas, pseudoaneurysms at the arterial puncture site, and retroperitoneal hemorrhage from bleeding at the groin access site, are among the most common complications of catheter ablation. Symptoms include hypotension and ipsilateral flank pain. Symptom onset is typically within hours of the procedure. Diagnosis can be established with CT or ultrasonography. Retroperitoneal hemorrhage cannot explain this patient's distant heart sounds, elevated central venous pressure, or pulsus paradoxus.

Key Point

  • Cardiac tamponade occurs in approximately 1% of patients who undergo catheter ablation procedures for atrial fibrillation; it is the most common serious complication and is likely to result in death if not recognized and treated urgently.

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Case 3

Correct answer: B. Outpatient cardiac telemetry.

This patient should have outpatient cardiac telemetry. She has a cryptogenic infarct with no clear source identified on arterial imaging, no evidence of atrial fibrillation (AF) or other high-risk embolic cause, and a stroke location that is not typical for lacunar infarcts. Accumulating data on patients with cryptogenic stroke indicate that an evaluation for AF with an outpatient rhythm monitor may yield a new diagnosis of AF in almost one third of patients. Given the high risk of recurrent stroke associated with AF, additional outpatient evaluation is warranted. The various options available for monitoring include mobile outpatient cardiac telemetry, 24-hour electrocardiographic monitoring, transtelephonic and event monitors, and implantable subcutaneous devices. Longer monitoring results in a higher diagnostic yield. In one study comparing 30-day monitoring to 24-hour monitoring, atrial fibrillation lasting for at least 30 seconds was found in 16.1% of patients monitored for 30 days vs. 3.2% of patients monitored for 24 hours, and AF lasting for at least 2.5 minutes was found in 9.9% of patients with prolonged monitoring vs. 2.5% of patients with 24-hour monitoring.

The combination of clopidogrel and aspirin is associated in the long term with a higher risk of hemorrhagic complications compared with a single antiplatelet agent only. A 2018 systematic review and meta-analysis showed that dual antiplatelet therapy with clopidogrel and aspirin given within 24 hours after high-risk TIA or minor ischemic stroke and continued for 10 to 21 days reduced subsequent nonfatal stroke risk but had no effect on all-cause mortality. It can be considered in patients who do not have a known cardiac source that requires anticoagulation. Aspirin should be continued following dual antiplatelet therapy for long-term secondary prevention of stroke.

Apixaban and similar anticoagulants have not been shown to be effective for the routine prevention of cryptogenic stroke. Warfarin and aspirin have similar rates of recurrent stroke in patients with noncardioembolic stroke; warfarin is not indicated as first-line therapy for stroke prevention in cryptogenic stroke.

Transesophageal echocardiography is unnecessary because the patient is in sinus rhythm and already has had structural imaging of the valves and chamber sizes, which makes a transesophageal echocardiogram likely to be of low yield. This diagnostic test also is invasive and costly and is of higher yield when used to evaluate for unusual causes of cardiac emboli, such as valvular endocarditis or intracardiac tumors.

Key Point

  • Evaluation of cryptogenic stroke with prolonged outpatient rhythm monitoring may yield a new diagnosis of atrial fibrillation in almost one third of patients.

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Case 4

Correct answer: D. Schedule follow-up within 1 week.

The most appropriate management is to schedule follow-up within 1 week of discharge. This patient was hospitalized for a heart failure exacerbation. Before discharge, it is important to initiate several strategies to prevent readmission. First, the reason for the heart failure exacerbation should be identified. Often, it is impossible to determine a cause; however, in a situation such as this one, addressing the reasons for the patient's nonadherence might prevent readmission. Second, patients should be receiving optimal doses of evidence-based medications before discharge. When medications, especially β-blockers, are restarted, it is important to begin at a low dose and slowly uptitrate over time. Third, patients should not be discharged until they have achieved euvolemia with diuresis, and their electrolyte levels and kidney function are optimized. Finally, appropriate follow-up should be scheduled. Studies have shown that patients seen within 1 week of a heart failure discharge have reduced admissions compared with those with later outpatient contact. The purpose of an early visit is to reinforce heart failure education, ensure proper medication use, evaluate volume status, and uptitrate or initiate medications as needed. This patient is euvolemic and is taking appropriate medications, and he should be scheduled for a follow-up visit within 1 week to prevent readmission.

Ivabradine reduces heart failure–associated hospitalizations in patients with chronic symptomatic heart failure with left ventricular ejection fraction less than or equal to 35% who are in sinus rhythm and taking guideline-directed medical therapy. This patient has atrial fibrillation, and ivabradine is not indicated.

ACE inhibitor and β-blocker therapies should be uptitrated to maximally tolerated doses before initiation of spironolactone. It is important to add an aldosterone antagonist later, but the dosage of the other agents should be maximized first.

There is no evidence of a survival advantage or reduction in stroke with cardioversion and maintenance of sinus rhythm in patients with atrial fibrillation, including those with heart failure. Therefore, the decision to institute a rate or rhythm control strategy largely depends on symptoms and patient preference. Patients who are asymptomatic can be managed with rate control only, with a resting heart rate goal of less than 110/min. Patients with tachycardia-induced cardiomyopathy, heart failure, or left ventricular ejection fraction of less than 40% may require more stringent rate control (heart rate of 60/min to 80/min at rest).

Key Point

  • Following heart failure hospitalization, early follow-up (within 1 week) should be scheduled to reinforce heart failure education, ensure proper medication use, evaluate volume status, and uptitrate or initiate medications as needed.

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Case 5

Correct answer: B. Dose-adjusted warfarin.

The most appropriate treatment to reduce the risk for thromboembolic events in this patient is dose-adjusted warfarin. In patients with hypertrophic cardiomyopathy (HCM), atrial fibrillation occurs in 20% to 25% of cases, and dyspnea often develops related to reduced left ventricular diastolic filling and increased left ventricular outflow tract obstruction. Restoration and maintenance of sinus rhythm are important in reducing symptoms. There is also a high incidence of stroke in patients with HCM who have atrial fibrillation, regardless of the type of atrial fibrillation (paroxysmal, persistent, or permanent), and anticoagulation to reduce thromboembolic risk must be considered. In this patient, acute anticoagulation with heparin or low-molecular-weight heparin would be appropriate before cardioversion, followed by administration of dose-adjusted warfarin to achieve an INR of 2 to 3. Two observational studies of patients with atrial fibrillation in the setting of HCM have shown reduced incidence of stroke with this strategy compared with antiplatelet therapy or no treatment.

The use of non–vitamin K antagonist oral anticoagulants, such as dabigatran, for thromboembolic risk reduction in patients with HCM has not been adequately studied, and the efficacy of these drugs in this situation is unknown. In patients with HCM who cannot take warfarin, non–vitamin K antagonist oral anticoagulants are reasonable as second-line therapy; however, use of warfarin in this patient is not contraindicated.

Although this patient's calculated CHA2DS2-VASc score is low (0 points), initiating aspirin therapy or foregoing therapy would be inappropriate according to current guidelines. The CHA2DS2-VASc scoring system is frequently used for decision making with regard to stroke risk-reduction therapy in patients with atrial fibrillation; however, the predictive use of this tool for patients with HCM has not been validated. A low CHA2DS2-VASc score may not adequately predict true thromboembolic risk in patients with HCM and should not be used to guide therapy.

Key Point

  • Patients with atrial fibrillation in the setting of hypertrophic cardiomyopathy should receive warfarin anticoagulation therapy to reduce thromboembolic risk.