309. Atrial Fibrillation: Situational As...

Dr. Daniel Ambinder (CardioNerds Co-Founder), Dr. Kelly Arps (Series Co-Chair and EP fellow at Duke University), Dr. Stephanie Fuentes Rojas (FIT Lead and EP fellow at Houston Methodist), and Dr. Ingrid Hsiung (Cardiology Fellow at Baylor Scott & White Health) discuss situational assessment of stroke and bleeding risk with expert faculty Dr. Hafiza Khan (Electrophysiologist at Baylor Scott & White Health). In this episode, we discuss stroke and bleeding risk in specific situations such as prior to cardioversion, triggered episodes, and perioperatively. These are scenarios that are commonly encountered and pose specific challenges. Episode notes were drafted by Dr. Stephanie Fuentes. Audio editing by CardioNerds Academy Intern, Dr. Maryam Barkhordarian.

This CardioNerds Atrial Fibrillation series is a multi-institutional collaboration made possible by contributions of stellar fellow leads and expert faculty from several programs, led by series co-chairs, Dr. Kelly Arps and Dr. Colin Blumenthal.

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Pearls and Quotes – Atrial Fibrillation: Situational Assessment of Stroke and Bleeding Risk

1. In patients with persistent atrial fibrillation with tachycardia induced cardiomyopathy, timely restoration of normal rhythm is important. In patients not on established oral anticoagulation one option is to wait 3 weeks on oral anticoagulation prior to considering cardioversion. Another option is to pursue TEE prior to cardioversion as TEE is currently the gold standard imaging modality to exclude a LAA thrombus.
2. Following cardioversion (chemical or electrical), anticoagulation must not be interrupted for 4 weeks due to atrial stunning. This is especially true for patients who have been in atrial fibrillation for an extended period of time.
3. Individualizing assessment of stroke and bleeding risk is imperative when determining perioperative anticoagulation (AC) management. ACC has a helpful app (ManageAnticoag App) to make this easier.
4. When considering AC in triggered atrial fibrillation (e.g., pneumonia, sepsis), it is important to consider the substrate that made the patient susceptible to developing atrial fibrillation. AC is favored in patients with high CHA₂DS₂-VAsC score and many traditional risk factors for atrial fibrillation as they are at high risk for future development of atrial fibrillation.
5. Atrial fibrillation is a marker of poor outcomes in patients who have undergone coronary artery bypass graft (CABG) surgery. It is unclear if patients should be started on long-term AC for new onset atrial fibrillation after CABG regardless of risk factors. This is currently being investigated in the PACES trial.

Notes – Atrial Fibrillation: Situational Assessment of Stroke and Bleeding Risk

How do we choose an imaging modality for excluding LAA thrombus exclusion prior to cardioversion?

• TEE is the gold standard. It also provides other information that is important for management of atrial fibrillation (e.g. LA size/volume, presence/degree of mitral regurgitation/stenosis, ejection fraction).
• Gated cardiac CTA may have a growing role for evaluation of LAA thrombus.

What is the data behind the recommendation for uninterrupted AC following cardioversion and what is atrial stunning?

• All patients should be anticoagulated for four weeks after cardioversion, regardless of the mechanism of cardioversion or CHA₂DS₂-VAsC score. As discussed in prior episodes, those who meet long term criteria for AC should be anticoagulated indefinitely.
• The term “atrial stunning” refers to the electro-mechanical dissociation of the LAA following cardioversion. The longer one is in atrial fibrillation, the longer it takes for the LAA contraction/LAA flow velocities to recover after restoration of normal rhythm. During the period of atrial stunning, there is increased risk of LAA thrombus formation, hence AC should not be interrupted. The first 72 hours post cardioversion are the highest risk for LAA thrombus formation followed by the subsequent 4 weeks.

What is the approach of perioperative AC management in patients with atrial fibrillation?

• ACC has a helpful app (ManageAnticoag App), to individualize the decision of when/how to stop and resume AC peri-procedurally.
• One needs to ascertain three factors: 1) surgical bleeding risk, 2) stroke risk, and 3) the patient’s individual bleeding risk (e.g., medications, supplements, renal function, etc.).
• The BRDIGE trial investigated the need to bridge patients on and off anticoagulation perioperatively. The trial was small and patient characteristics of the study (mostly male, low percentage of patients with high CHADS score) do not allow for generalizability of study findings to all patients.
• Many patients do not require perioperative bridging, but individual patient factors should be used to make this decision. High risk features that warrant heparin bridging include recent stroke, mechanical valve, or mitral stenosis. Should consider bridging in patients with high CHA₂DS₂-VAsC score as these patients only made up a small portion of the BRIDGE trial.

What is the approach to AC in patients with triggered atrial fibrillation?

• Similar to a fire, atrial fibrillation requires a substrate (i.e., combustible material) and a trigger (i.e., a match) to initiate. Though you can treat and therefore remove the trigger (e.g., pneumonia), patients with a substrate conducive to atrial fibrillation remain at high risk of atrial fibrillation in the future. If they were to convert to atrial fibrillation without clear symptoms in the future, they would be at risk for stroke and might not be started on AC. As such, long-term AC should be evaluated in a similar manner to those with paroxysmal or persistent atrial fibrillation without a clear trigger.
• The patient population with true “triggered” atrial fibrillation may be limited to those with thyrotoxicosis as hyperthyroidism can trigger atrial fibrillation even in patients with structurally normal hearts and background risk for future atrial fibrillation. 
• Atrial fibrillation after cardiac surgery (e.g., CABG, mitral valve repair/replacement) should be managed with a coordinated heart team approach. Anticoagulation should likely be favored if bleeding risk is acceptable and patient has known risk factors, especially in valve surgeries where patients often have had longstanding LA pressure or volume overload. Atrial fibrillation following CABG has been associated with poor outcomes, though it is currently unclear if patients without traditional risk factors require long-term AC. This is currently being studied in the PACES trial.

References

1. January, C.T, Wann, L.S, Alpert, J.S., Calkins, H, Cigarroa, J.E., Cleveland, J.C., Conti, J.B., Ellinor P.T et al 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American college of Cardiology/American heart Asocciation Task Force on Practice Guidelines and the Heart Rhythm Society. Journal of the American College of Cardiology, 6421, e1-76.
2. Dagres N, Kornej J, Hindricks G, et al. Prevention of Thromboembolism After Cardioversion of Recent-Onset Atrial Fibrillation. J Am Coll Cardiol. 2013 Sep, 62 (13) 1193–1194.https://doi.org/10.1016/j.jacc.2013.06.019