A 55M h/o HTN presents with 5 hours of palpitations that woke him from sleep.
His complaint is that the sensation of his fast beating heart is uncomfortable. There is no chest pain, no SOB.
There are no other associated symptoms.
Vitals: HR 145 BP 120/65 RR 12 T98.0 98%
Patient is well appearing, exam unremarkable other than a tachy radial pulse.
EKG shows atrial fibrillation with RVR.
Routine ancillary ED studies are performed to investigate possible etiologies of his Afib.
(How) do you want to manage his stable afib?
Specifically, do you want to perform electric cardioversion, chemical cardioversion, chemical rate control, or sit on hands and admit/obs?
There is not consensus on the optimal treatment of a patient with stable, presumed new-onset afib in the ED.
Why do we address afib at all? The Framingham data inform us that in chronic afib the risk of stroke is increased by 5 fold, and the risk of death is doubled. Further, a rapid ventricular rate often results in symptoms such as chest discomfort and reduced exercise tolerance that decreases quality of life. For some time, management of new-onset afib in hospitals or clinic was generally directed towards rhythm control, using oral anti-arrhythmics such as amiodarone, sotalol, propafenone etc. to maintain a sinus rhythm.
The AFFIRM trial (4060 patients, 2002) randomized patients into two groups, either a rate control (<80-110 BPM) or a rhythm control strategy, and found that rate control was not inferior in outcome of death or quality of life, and resulted in fewer hospitalizations and medication adverse effects. The smaller RACE trial (522 patients, 2002) demonstrated similar results. Subsequently, management of Afib in the US, whether inpatient, outpatient, or ED, has trended towards rate control with antiplatelet or anticoagulation therapy as needed per risk stratification. Rate control is usually achieved with betablockers or nondihydropyridine calcium channel blockers (verapamil or diltiazem).
IN THE ED:
There is not data to suggest that new onset (<48hr) atrial fibrillation with RVR in an otherwise hemodynamically stable patient is itself an immediately dangerous condition requiring emergent action. Benefits of early cardioversion are that cardioversion is more successful when performed <48 hours, and may save the patient time, money and provide earlier symptom relief. The feared complication of cardioversion in afib is a thromboembolic event with end organ damage, namely, stroke. There is a 0.8% risk of stroke after cardioversion in a patient not on chronic anticoagulation (patient described in vignette). For those on therapeutic anticoagulation for h/o afib with paroxysmal conversion to afib, the risk is 2%. Even if cardioversion is successful and the person is in sinus rythym, the patient remains at increased risk of thromboembolism for up to 4 weeks due to the delayed return of strong, organized atrial contraction.
Several small studies have examined ED afib protocols, including early ED cardioversion, and the results and discussions seemingly support early cardioversion, however they are limited by extent of followup, and small sample size.
Of note, often in paroxysmal afib the heart will revert to sinus rhythm without any intervention, this occurs in up to 27% of patients who were observed for 7 hours in one study.
The AHA/ACC outlines 3 objectives for stable afib management: 1) rate control, 2) prevention of thromboembolism, and 3) correction of rhythm disturbance. However these are not guidelines specific for acute afib episodes, and thus are not literal guidelines for ED management.
If the ED physician does not feel compelled to perform cardioversion in stable afib due to the concern for immediate or delayed thromboembolic event, risks of procedural sedation, or lack of immediate medical benefit to electrocuting someone with stable vital signs, there seems to be a generally accepted ED pathway for stable new-onset afib:
1) Treat symptoms via rate control
2) Admit or place in obs unit for echo and initiation of anticoagulation with cardiology consult for possible planned cardioversion.
Interestingly, rates of ED intervention and discharge of patients with afib are much higher in Canada compared to the US; proposed contributing factors are differences in comorbid diagnoses, availability of prompt followup, and a different medicolegal environment.
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