Can Atrial Fibrillation Cause Pulmonary Embolism?
Yes, atrial fibrillation (AF) can increase the risk of pulmonary embolism (PE), particularly in the first few months after AF diagnosis, though the relationship is bidirectional with each condition potentially leading to the other. 1, 2
Pathophysiological Relationship Between AF and PE
How AF Can Lead to PE
- Right atrial thrombus formation: While AF is primarily associated with left atrial thrombus formation and stroke risk, it can also lead to right atrial appendage clot formation that may embolize to the pulmonary circulation 2
- Temporal relationship: The risk of PE is significantly higher in the first 30 days after AF diagnosis (40.2 vs. 5.7 per 1000 person-years in men and 55.7 vs. 6.6 per 1000 person-years in women) 3
- Shared risk factors: AF and PE share multiple common risk factors including:
- Advanced age
- Heart failure
- Obesity
- Inflammatory states 2
How PE Can Lead to AF
- Right-sided pressure overload: PE can cause right ventricular strain, leading to increased right atrial pressure and subsequent atrial remodeling
- Inflammatory response: PE triggers release of inflammatory cytokines that may promote AF development
- Acute presentation: AF can be seen as a presenting sign of PE or during the early phase of PE 2
Evidence from Guidelines and Research
Guideline Evidence
The ACC/AHA/ESC guidelines specifically list pulmonary embolism as an acute cause of AF, acknowledging the relationship between these conditions 1. The guidelines state: "Atrial fibrillation may be related to acute, temporary causes, including... pulmonary embolism or other pulmonary conditions." 1
Research Evidence
Recent studies show conflicting results:
- Supporting evidence: A 2021 Swedish Nationwide Registry Study found that AF is strongly associated with increased risk of VTE (including PE) during the first months after diagnosis 3
- Contradicting evidence: A 2020 retrospective registry study concluded that after adjustment for age and comorbidities, AF without oral anticoagulation was not independently associated with increased PE risk (HR 1.03, CI 0.94-1.13) 4
Clinical Implications
Risk Assessment
- The risk of thromboembolism in AF correlates with the CHA₂DS₂-VASc score 2
- Non-paroxysmal AF carries a higher risk of thromboembolism than paroxysmal AF (adjusted HR 1.384,95% CI: 1.191-1.608) 1
Anticoagulation Considerations
- Anticoagulation therapy initiated for stroke prevention in AF may simultaneously reduce PE risk 3
- When both conditions coexist, anticoagulation decisions should consider:
- PE-related factors (provoked vs. unprovoked, cancer presence)
- AF-related factors (CHA₂DS₂-VASc score)
- Bleeding risk 2
Common Pitfalls in Management
- Overlooking the relationship: Failing to consider AF as a potential cause or consequence of PE
- Delayed anticoagulation: Not initiating anticoagulation promptly after AF diagnosis, when the PE risk is highest
- Attributing symptoms solely to AF: Symptoms like dyspnea or tachycardia might be due to PE in AF patients
- Inadequate monitoring: Not monitoring for PE development in newly diagnosed AF patients
In summary, while the relationship between AF and PE is complex and bidirectional, clinicians should be aware of the increased risk of PE following AF diagnosis and consider appropriate preventive measures, particularly anticoagulation therapy in high-risk patients.