Relationship Between Atrial Fibrillation and Pulmonary Embolism
Yes, there is a significant bidirectional relationship between atrial fibrillation (AFib) and pulmonary embolism (PE), with AFib recognized as both an acute trigger for PE and a consequence of PE, particularly during the acute phase.
AFib as a Cause of PE
Acute PE Risk After AFib Diagnosis
- The risk of PE is dramatically elevated immediately after AFib diagnosis, with a 10.88-fold increased hazard during the first 6 months (crude incidence rate of 18.5 per 1000 person-years), then declining but remaining elevated at 1.72-fold throughout long-term follow-up 1.
- AFib patients demonstrate substantially higher VTE rates in the first 30 days after diagnosis (40.2 vs. 5.7 per 1000 person-years in men; 55.7 vs. 6.6 in women), with hazard ratios of 6.64 and 7.56 respectively 2.
- This risk decreases as anticoagulation therapy is initiated, with VTE risk normalizing after 9 months in men but remaining slightly elevated in women 2.
Mechanism: Right Atrial Thrombosis
- AFib patients with PE have significantly lower rates of concomitant deep vein thrombosis (21% vs. 44% in non-AFib PE patients), suggesting clots may originate from the right atrium rather than lower extremities 3.
- The CHA2DS2-VASc score correlates with PE risk in AFib patients, indicating shared thrombotic mechanisms 4, 3.
PE as a Cause of AFib
PE as an Acute Trigger
- Pulmonary embolism is explicitly recognized as an acute, temporary cause of AFib in major cardiology guidelines 5.
- PE triggers AFib through right ventricular pressure overload and inflammatory cytokine release 4.
- Hospitalization for PE represents a strong risk factor for provoking AFib 6.
Clinical Characteristics of PE-Associated AFib
- Patients with paroxysmal AFib during acute PE demonstrate more severe right ventricular dysfunction, with higher estimated systolic pulmonary artery pressure (56 vs. 48 mmHg in permanent AFib vs. 47 mmHg in sinus rhythm) and shorter acceleration time (58 vs. 65 vs. 70 ms) 7.
- This suggests a direct relationship between PE severity and paroxysmal AFib episodes 7.
Shared Risk Factors and Pathophysiology
Common Risk Factors
- Both conditions share multiple risk factors including advanced age, obesity, heart failure, and inflammatory states 4.
- The 2024 ESC guidelines explicitly list venous thromboembolism as associated with AFib 5.
Thrombotic Mechanisms
- AFib creates a prothrombotic state through atrial stasis, endothelial dysfunction, and systemic hypercoagulability 5.
- Chronic obstructive pulmonary disease and pulmonary conditions trigger atrial dysfunction through hemodynamic and hypoxic stress 8.
Clinical Implications for Anticoagulation
Dual Indication for Anticoagulation
- Patients with both AFib and PE have overlapping indications for anticoagulation, as direct oral anticoagulants (DOACs) like apixaban and rivaroxaban are FDA-approved for both stroke prevention in nonvalvular AFib and treatment/prevention of PE 9, 10.
- Treatment decisions should consider both PE-related factors (provoked vs. unprovoked, active cancer, prior recurrence) and AFib-related factors (CHA2DS2-VASc score), along with bleeding risk 4.
Prognostic Considerations
Mortality Impact
- Paroxysmal AFib during acute PE does not increase short-term mortality (6.5%) compared to sinus rhythm (5%), but permanent AFib carries significantly higher mortality (25%) 7.
- The risk of PE in AFib is independent of intermediate ischemic stroke, indicating separate pathophysiological mechanisms 1.
Clinical Pitfalls to Avoid
- Do not assume all PE in AFib patients originates from lower extremity DVT—consider right atrial thrombus formation, especially when DVT is absent 3.
- Do not overlook PE as a reversible cause of new-onset AFib—successful treatment of PE may eliminate AFib 5.
- Do not delay anticoagulation in newly diagnosed AFib—the highest VTE risk occurs in the first 30 days, and early anticoagulation reduces both stroke and PE risk 2.
- Use CHA2DS2-VASc rather than CHADS2 for risk stratification in AFib patients, as it is more sensitive for predicting PE (13.6% vs. 44.5% classified as low-intermediate risk) 3.