1. Answer: B. TEE evidence of LAA thrombi is seen in approximately 13% of patients presenting with nonvalvular AF of more than three days duration.

2. Answer: D. SEC is present in over 50% of all patients with AF and in over 80% of those with an LAA thrombus or a recent thromboembolic event. Patent foramen ovale is an important, albeit controversial cause of cryptogenic stroke in the young and is unassociated with stroke in AF. LAA flow velocities >50 cm/s are normal, as is LA volume index of 25 mL/m² (normal <35 mL/m²). Anomalous pulmonary venous drainage is associated with sinus venosus atrial septal defects, but not with stroke.

3. Answer: B. LA size is important prognostically in AF. Progressive enlargement is associated with a decreased probability of maintaining sinus rhythm. LAA velocity is also thought to be a predictor of the likelihood of maintaining sinus rhythm after cardioversion. Choice B has the smallest LA size and highest LAA velocity and is therefore the best option.

4. Answer: C. Atrial fibrillation is the best choice among these options. E/′ should not be used to determine PCWP in patients with mitral valve prostheses or severe MAC, as e′ velocities may be inaccurate.

5. Answer: B. Although much less common than LAA thrombi in patients with AF, right atrial (RA), or RAA thrombi occur in 1%-6% of cases (vs. 10%-15% for LAA thrombi). The majority of patients with RAA thrombi also have LAA thrombi. Though no randomized trials have been reported, cardioversion should likely be deferred in patients who have isolated RA thrombi so as to prevent pulmonary embolism.

6. Answer: A. In a consecutive series of more than 350 hospitalized patients with nonvalvular AF, the incidence of cardioversion-related thromboembolism was 0.8% in patients without screening TEE and AF of <48 hours. In a retrospective multicenter study of 3,143 similar patients from Finland, definite embolic events occurred in 0.7% of patients. At highest risk, were patients with heart failure and diabetes.

7. Answer: C. In a study looking at patients with nonrheumatic AF, resolution of thrombi occurred in approximately 75% after 4 weeks of anticoagulation therapy.

8. Answer: B. The ability of TTE to identify or exclude LA or LAA thrombi is limited, with a reported sensitivity of 39%-63%. This is largely due to poor visualization of the LAA.

9. Answer: C. The larger RAA width and lack of anatomic remodeling may partially explain the substantially lower prevalence of RAA thrombus found among patients with AF. All the other choices are false statements.

10. Answer: A. The patient in choice A has a resting gradient of 64 mm Hg across the LVOT, which is quite elevated. Patients with hypertrophic cardiomyopathy and an LVOT obstruction often have compromised left ventricular (LV) filling due to abnormal relaxation secondary to myofibril disarray. Additionally, systolic anterior motion of the anterior leaflet of the mitral valve, which results in outflow tract obstruction and mitral regurgitation, can severely compromise cardiac output. The development of AF in such a patient would compromise LV filling significantly. Choices B through D are essentially mild forms of their respective pathologies.

11. Answer: E. ACC/AHA 2014 guidelines recommend that anticoagulation should be initiated if AF does not revert to sinus rhythm similar to the management of nonsurgical patients. AF and atrial flutter occur frequently after cardiac surgery. The prevalence of AF is more frequent in valvular surgery than in CABG and greatest when combined (CABG plus valve surgery). AF is reported to be between 15% and 40% after CABG, 37% and 50% after valve surgery, up to 60% in CABG plus valve replacement. AF is reported to occur in 11%-24% after cardiac transplantation. Despite the reduction of AF with prophylactic medical therapy, the reduction in stroke has been found to be statistically nonsignificant.

12. Answer: C. The CLOTS Multicenter Pilot Trial found that the combination of harmonic imaging with IV contrast was useful in the detection of thrombus by TTE. Although cardiac computed tomography with iodinated contrast and delayed imaging could be used to evaluate LAA thrombi, EBCT would not, as it is not used with IV contrast and primarily used for calcium scoring.

13. Answer: B. Prolonged rhythm monitoring in patients with AF document frequent episodes of clinically silent periods of AF. TEE studies suggest that 25% of patients with paroxysmal AF demonstrate periods in which the ECG and body of the LA are in sinus rhythm while the LAA has a fibrillatory pattern on pulse-wave Doppler. Aortic plaque is found in over 50% of patients with AF with nearly 50% of these with complex plaque. Complex plaque is associated with thromboembolism. In the AF population, at least moderate mitral regurgitation has been shown to be protective for clinical stroke.

14. Answer: E. Though TTE with echo contrast improves definition of the LAA, it has not been shown to be as efficacious as TEE for identifying LAA thrombi. Cardiac MRI has an inferior sensitivity and specificity for LAA thrombi, likely due to the irregular rhythm and slow LAA flow leading to stagnant blood flow and false positive interpretation. Computed tomography has a high sensitivity for LAA thrombus, but only modest specificity. ICE with the ICE probe advanced into the main pulmonary artery has been shown to be extremely accurate (vs. TEE) for identifying thrombus in the LAA. Though expensive, the catheter is the same catheter used in the subsequent pulmonary vein isolation procedures to guide the transseptal puncture.

15. Answer: D. Though there may be apparent sinus rhythm with full recovery of the ECG p wave, atrial mechanical function as assessed by transmitral Doppler may remain depressed for several weeks after successful cardioversion. Recovery of LA mechanical function is related to the duration of AF prior to cardioversion, with full recovery within 24 hours for those with AF of <2 weeks, within a week for those with AF of <4-6 weeks, and within a month for those with AF for >2 months.

16. Answer: D. Figure 27-1 shows prominent spontaneous echo contrast (SEC) in the LAA. SEC is an independent predictor of thromboembolic risk and associated with an increase in embolic rate in patients with AF. Mitral regurgitation appears to lessen the frequency of SEC. Warfarin does not impact the prevalence of SEC. There is a strong association between LA SEC and LA thrombi. The prevalence of SEC occurs more frequently in AF than in atrial flutter. There is no known association between SEC and LA myxoma.

17. Answer: B. The risk of stroke is increased with marked reductions in blood flow velocity, particularly in the LAA or posterior LA. A low-appendage ejection flow velocity is associated with the presence of appendage thrombus and with dense SEC. LA blood flow velocity (>40 cm/s) is thought to be a predictor of the likelihood of maintaining sinus rhythm after cardioversion. There are no definitive findings that suggest that this patient has severe pulmonary hypertension or should be referred for PVI based on atrial appendage velocities.

18. Answer: C. Cor triatriatum sinister is differentiated from a supravalvular mitral ring by the position of the LAA (Fig. 27-15, white arrow). In cor triatriatum sinister, the left appendage is part of the distal (mitral valve) atrial chamber, while the LAA is part of the proximal (pulmonary vein) atrial chamber in patients with a supravalvular ring.

Cor triatriatum may be associated with other congenital abnormalities (atrial septal defect, persistence of left superior vena cava), but is commonly seen in isolation when found in an adult. It may be associated with increased gradients across the membrane, leading to this patient’s symptoms. However, this finding lacks specificity and does not confirm a diagnosis. Pulmonary vein stenosis is not commonly associated with cor triatriatum and would not confirm a diagnosis.

Given Figure 27-15 and this patient’s symptoms, an artifact cannot be assumed. Such a finding should be further investigated with multiple views, with and without Doppler. If TTE findings are ambiguous, a TEE may be warranted.

19. Answer: C. Figure 27-4 reveals a complex aortic plaque (pedunculated with mobile components). Patients who experience a cerebral event should be aggressively treated for secondary prevention with aspirin, statins, blood pressure control, smoking cessation, and glycemic control (if diabetic). Patent foramen ovale closure is not warranted given this patient’s age and complex aortic atheroma. Although there is controversy with regard to warfarin therapy and aortic arch plaque, this patient is already therapeutic on antithrombotic agents for his AF. There is no data to demonstrate that a goal INR of 3-4 will improve the outcome of patients with aortic atheroma. Confirmation by chest CT is not warranted as Figure 27-4 represents atheroma and not aortic dissection.