Please see also the Internet Book Of Critical Care‘s [link is to the TOC] Atrial Fibrillation (AF) & Flutter complicating critical illness*. January 6, 2017 by Dr Josh Farkas.
*The above IBCC chapter is outstanding. And it is the resource for reviewing the treatment of atrial fibrillation in the critically ill patient.
#289 is a brief recap (26:46) of #159 Atrial Fibrillation Review and Update (1:20:04),
JULY 8, 2019 By CYRUS ASKIN
I have embedded both podcasts in this post for ease of review. The show notes below are from #159.
All that follows is from the show notes of #159:
Top 5 expert insights from Dr. Furgerson:
1. THE KEYS TO PREVENTION ARE HELD BY THE PRIMARY CARE PROVIDER.
The power of the relationship between a patient and their primary care provider cannot be overstated! In this case, modifiable risk factors for atrial fibrillation: obesity, obstructive sleep apnea, hypertension and alcohol use disorder – to name a few – can and should be addressed early and often!
2. ATRIAL FIBRILLATION IS GENERALLY A FUNCTION OF STRUCTURAL HEART DISEASE THAT CAUSES ELEVATION OF LEFT ATRIAL PRESSURE, ESPECIALLY HYPERTENSION.
Long standing hypertension leads to left ventricular hypertrophy and elevated pressure in the left atrium (Note: it’s probably more complicated than that —listen to #150 HFpEF). This in turn causes dilation of the left atrium which disrupts the physiologic electrical conduction of the heart, setting the stage for atrial fibrillation. Less commonly, atrial fibrillation occurs in the setting of a structurally normal heart.
3. RATE CONTROL, IN MOST CASES OF ATRIAL FIBRILLATION, IS THE PREFERRED APPROACH TO THERAPY.
Symptomatic tachycardia and stroke risk are the major issues seen in patients with atrial fibrillation. Most patients with paroxysmal atrial fibrillation (i.e. suddenly starts and terminates spontaneously or with intervention within 7 days) respond well to rate control alone, typically with a beta-blocker such as metoprolol. Some patients may need two agents.
Other patients, such as those with concomitant heart failure may benefit from early rhythm control strategies, even though antiarrhythmic agents can be more difficult to manage. These patients may also be candidates for early ablation.
On the other end of the spectrum, young, highly-athletic patients may develop paroxysmal atrial fibrillation as a function of exercise-induced cardiac remodeling. These patients may be great candidates for an early ablation strategy for persistent symptoms.
4. … SPEAKING OF STROKE RISK, WHAT ABOUT ANTICOAGULATION?
The decision to initiate or defer anticoagulation is a complicated one, best handled through shared decision making via a patient centered approach.
Remember the CHA2DS2VASc score for calculating stroke risk in a patient (see this calculator from MDCalc).
The other side of the coin is bleeding risk which also must be considered and may be more nuanced than stroke risk. One place to start is the HAS-BLED score, an accepted risk calculator cited in the JACC’s ACC/AHA/HRS 2019 Update on Atrial Fibrillation (again, see this calculator from MDCalc).
Generally speaking, if a patient’s bleeding risk is not markedly elevated, a CHA2DS2VASc score ≥ 2 for men or ≥ 3 for women, indicated a patient who would benefit from anticoagulation.
What agent to start? Again, requires shared decision making via a patient centered approach. The non-vitamin K oral anticoagulants (NOACs) are excellent options for non-valvular (afib WITHOUT mod-to-severe mitral stenosis or a mechanical heart valve) but dosing must be done based on renal function. Vitamin-K antagonists (VKAs, warfarin in the U.S.) are the drug-of-choice for valvular atrial fibrillation.
5. TO CARDIOVERT OR NOT TO CARDIOVERT…
Synchronized cardioversion (a shock delivered in synchrony with the patient’s native QRS complex) can be used to electrically convert a patient in atrial fibrillation to normal sinus rhythm in certain circumstances.
Patients with hypotension/hemodynamic instability, or those with pre-excitation on their EKG are good candidates for cardioversion which should be done without hesitation (i.e. TEE to check for mural thrombus is NOT required for emergency cardioversion).
Acute, ongoing ischemia with new-onset atrial fibrillation and rapid ventricular response – Class 1c recommendation for urgent cardioversion per 2014 ACC/AHA/HRS guideline
Highly symptomatic patients: Consider cardioversion. May defer TEE in patients with a known long-standing history of atrial fibrillation, adherent to chronic anticoagulation.
WHAT ARE THE OPTIONS FOR CARDIOVERSION FOR NEW-ONSET ATRIAL FIBRILLATION OR ATRIAL FIBRILLATION OF UNCERTAIN DURATION?
- TEE prior to cardioversion while on effective anticoagulation with at least 4 weeks of therapeutic anticoagulation to follow (continue indefinitely if suggested by stroke risk)
- Alternatively, may therapeutically anticoagulate for at least 3 weeks prior to cardioversion and continue for at least 4 weeks afterwards, in lieu of TEE.
Atrial Fibrillation Studies, Guidelines & Insights From The Show
In some ways, this comprehensive reference discussing the pathophysiology, diagnosis and management of atrial fibrillation in numerous populations was the cornerstone for our discussion. We specifically examined the interplay between heart failure and atrial fibrillation with Dr. Furgerson. He mentioned the preferential use of rhythm control in atrial fibrillation when a patient is thought to develop heart failure secondary to their atrial fibrillation (see page e46 in the above document for more). Additionally, with respect to atrial fibrillation and heart failure in general, there is a IIa recommendation to combine digoxin (a rate and rhythm control agent) with a beta-blocker, if necessary to improve symptoms (see section 7.9).
This is an important update to the aforementioned guideline which we discussed during our show. Dr. Furgerson specifically pointed out the following:
- Class 1a indication for NOACs over VKAs in most cases of atrial fibrillation
- Class 1b indiciation for weight loss in obese patients – evidence suggests weight loss “reduced symptom burden and severity and reduced the number of AF episodes and their cumulative duration ( see Abed, 2013)
- Both warfarin and apixaban, are acceptable for patients with CKD-5/ESRD (class 2b)
- Class 2b indication for catheter ablation for atrial fibrillation in HFrEF due to “New evidence, including data on improved mortality rate, has been published for atrial fibrillation catheter ablation compared with medical therapy in patients with heart failure.”