Should a Positive Bubble Study with PFO Warrant Cardiology Referral?
Yes, a positive bubble study showing transatrial shunt with Valsalva indicating possible PFO warrants cardiology referral, particularly if the patient is under 60 years old or has had a cryptogenic stroke/TIA.
Clinical Context Determines Urgency
The decision to refer depends critically on why the echocardiogram was ordered in the first place:
If Patient Has Had Cryptogenic Stroke or TIA:
- Immediate cardiology referral is indicated 1, 2
- PFO is found in approximately 50% of patients ≤60 years with cryptogenic stroke, compared to 25% in the general population 2
- The Risk of Paradoxical Embolism (RoPE) score should be calculated using: age, history of stroke/TIA, diabetes, hypertension, smoking, and cortical infarct on imaging 2
- Patients with RoPE scores of 9-10 have 77% PFO prevalence, while scores <3 have only 23% prevalence (similar to general population) 2
Critical evidence: In well-selected patients <60 years with cryptogenic stroke, PFO closure reduces annualized stroke recurrence from 1.09% to 0.47% (adjusted HR 0.41,95% CI 0.28-0.60) over median 57-month follow-up 2. For PASCAL "probable" patients (younger, no vascular risk factors, high-risk PFO features), there's a 90% relative risk reduction (HR 0.10, absolute risk reduction 2.1%) 2.
If Patient Is Asymptomatic (Incidental Finding):
- Routine cardiology referral is generally not warranted 3, 4
- PFO is present in 25-27% of healthy individuals and most remain asymptomatic without increased stroke risk 4, 5
- One study found that among 715 patients referred for bubble studies, only 31% of those with detected PFO had any subsequent management change 3
Special Clinical Scenarios Requiring Referral:
Platypnea-orthodeoxia syndrome (dyspnea and hypoxemia worsening when upright, improving when supine):
- Requires urgent cardiology referral for potential PFO closure 6
- Look for: postural oxygen desaturation, unexplained dyspnea in elderly, enlarged aortic root on echo 6
Recurrent migraine with aura:
Diving or high-altitude activities:
- May warrant referral for risk stratification 8
Thrombophilia without prior embolic events:
- Limited evidence suggests potential benefit of closure, but this remains controversial and requires individualized cardiology assessment 9
Key Pitfalls to Avoid
Don't refer every incidental PFO: Studies show bubble studies are frequently performed in patients with readily identifiable stroke causes (8.7% had atrial fibrillation, 9.2% had ≥70% carotid stenosis) where PFO is likely incidental 3
Age matters: The association between PFO and cryptogenic stroke is strongest in patients <55 years (45.9% prevalence) versus older patients 7
Don't assume all PFOs need closure: Even in cryptogenic stroke, PASCAL "unlikely" patients (older, vascular risk factors, no high-risk PFO features) showed no benefit from closure but had higher complication rates including atrial fibrillation 2
Transesophageal echo (TEE) is needed for closure planning: If closure is being considered, TEE provides superior anatomical detail for procedural planning and detection of atrial septal aneurysm (a high-risk feature) 1
Practical Algorithm
Step 1: Determine clinical context
- Cryptogenic stroke/TIA in patient <60 years → Refer to cardiology
- Symptomatic (platypnea-orthodeoxia, severe migraine) → Refer to cardiology
- Asymptomatic incidental finding → No routine referral needed
Step 2: If cryptogenic stroke, calculate RoPE score
- Score ≥7 → Strong indication for cardiology referral
- Score 4-6 → Moderate indication, refer for evaluation
- Score <3 → PFO likely incidental, consider other causes first
Step 3: Document high-risk features from bubble study
- Large shunt (>20 bubbles in left atrium)
- Atrial septal aneurysm present
- These features increase likelihood of PFO-related events and favor closure 1, 2
The complication rate of bubble studies is very low (0.1% TIA rate) but warrants informed consent 3.