What is the management approach for a patient with a history of Kawasaki disease presenting with syncope?

Management of Syncope in Patients with History of Kawasaki Disease

A patient with prior Kawasaki disease presenting with syncope requires immediate cardiac evaluation with ECG and echocardiography, as syncope may represent life-threatening arrhythmia or acute coronary syndrome from thrombosed aneurysms or progressive stenotic lesions. 1, 2

Immediate Risk Assessment

High-Risk Features Requiring Emergency Intervention

• Syncope in post-Kawasaki patients is a cardiac emergency until proven otherwise, particularly if associated with chest pain, exertion, or palpitations 2, 3
• Cardiac causes of syncope carry 18-33% one-year mortality compared to 3-4% for non-cardiac causes 2
• In adults with coronary lesions from Kawasaki disease, syncope has been documented as a presenting feature of rapid ventricular tachycardia requiring defibrillator implantation 3

Critical Initial Evaluation

Obtain immediate ECG looking for:

• Severe bradyarrhythmias (sinus bradycardia <40 bpm, Mobitz II or third-degree AV block, sinus pauses >3 seconds) 2
• Tachyarrhythmias (rapid SVT, ventricular tachycardia, polymorphic VT) 2
• Conduction abnormalities (bundle branch blocks, QRS ≥120 ms) 2
• Signs of acute ischemia or infarction 1

Perform urgent echocardiography to assess:

• Presence and size of coronary aneurysms 1, 4
• Left ventricular function (ejection fraction <40% indicates high risk) 3
• Regional wall motion abnormalities suggesting ischemia 1

Risk Stratification Based on Coronary Status

Patients with Known Giant Aneurysms (≥8mm)

• These patients face the highest risk of thrombotic occlusion and sudden death 1, 5
• Syncope may represent acute coronary syndrome from complete thrombosis of aneurysm or rupture of stenotic plaque 1
• Immediate coronary angiography should be considered if acute coronary syndrome is suspected 1
• Electrophysiologic studies may be warranted to evaluate for inducible ventricular arrhythmias 3

Patients with Regressed or Moderate Aneurysms

• Even angiographically "regressed" aneurysms have persistent endothelial dysfunction and myointimal thickening 1
• These vessels remain at risk for progressive stenosis and thrombosis 1
• Stress testing with myocardial perfusion imaging is mandatory to detect reversible ischemia 1

Patients Without Known Coronary Involvement

• Do not assume low risk—coronary abnormalities may have been missed in childhood or developed later 1, 6
• One-third of adults with Kawasaki-related coronary disease had no documented history of the acute illness 6
• Young age does not exclude cardiac causes of syncope 2

Acute Management Algorithm

If STEMI or Acute Coronary Syndrome Suspected

For acute thrombosis in acute/subacute phase:

• Systemic thrombolytic therapy or intravenous antiplatelet therapy (abciximab) may be preferred over mechanical intervention 1
• PCI is challenging in acutely occluded aneurysms; thrombectomy catheters should be considered if attempted 1
• CABG should not be considered due to delays in restoring flow 1

For adults with remote Kawasaki history:

• Emergency coronary angiography to determine if atherosclerotic disease versus thrombosed aneurysm 1
• Intravascular ultrasound (IVUS) is critical to demonstrate true luminal dimensions and guide stent deployment 1
• Standard PCI techniques may be appropriate if typical atherosclerotic disease 1

If Arrhythmia Suspected

• Continuous cardiac monitoring is mandatory 2
• Consider electrophysiologic studies if ventricular arrhythmia suspected, particularly in patients with giant aneurysms or low ejection fraction 3
• Implantable cardioverter-defibrillator placement may be necessary for documented rapid ventricular tachycardia 3

Admission Criteria

Admit all patients with:

• History of coronary artery aneurysms (any size) 2
• Age >60 years with syncope 2
• Associated chest pain or symptoms compatible with acute coronary syndrome 2
• Abnormal ECG findings 2
• History of congestive heart failure or ventricular arrhythmias 2

Long-Term Management After Syncope Episode

Surveillance Requirements

• Serial stress testing with myocardial perfusion imaging to detect progressive ischemia 1, 5
• Regular echocardiographic monitoring for ventricular function and aneurysm progression 4
• Consider coronary CT angiography or cardiac MRI to understand pathophysiology 1

Antithrombotic Therapy Optimization

• Patients with giant aneurysms require combination anticoagulation (warfarin or LMWH) plus aspirin 1
• Those with moderate aneurysms may need dual antiplatelet therapy (aspirin plus clopidogrel) 1
• Therapeutic anticoagulation targets must be maintained to prevent thrombosis 1

Activity Restrictions

• Patients at risk for myocardial ischemia or exercise-induced arrhythmia must restrict high dynamic or static activities 1
• Exercise-induced symptoms precipitate cardiac events in 82% of adults with Kawasaki-related coronary disease 6
• Decisions should be guided by stress testing results and presence of exercise-induced arrhythmias 1

Critical Pitfalls to Avoid

• Never assume a normal ECG excludes cardiac causes—paroxysmal arrhythmias and early channelopathies may not be evident 2
• Do not rely on childhood echocardiograms—stenotic lesions are frequently progressive and develop over years 1
• Recognize that symptoms may remain silent for decades before presenting with sudden death or myocardial infarction in adulthood 3, 6
• Ring calcification on chest X-ray is highly suggestive of giant aneurysms in young adults with syncope 6