What kind of structural cardiac anomalies are often found on a patient with Wolff-Parkinson-White (WPW) pattern, particularly type A?

Structural Cardiac Anomalies in Wolff-Parkinson-White Pattern

Most patients with WPW pattern have structurally normal hearts, but when structural abnormalities are present, the most commonly associated conditions are Ebstein's anomaly, mitral valve prolapse, hypertrophic cardiomyopathy, and PRKAG2-related glycogen storage cardiomyopathy. 1, 2

Prevalence of Structural Heart Disease

• The vast majority (93-95%) of WPW patients have no structural heart disease, with only 5-7% demonstrating cardiac abnormalities in large systematic reviews 1
• Among asymptomatic WPW patients specifically, structural heart disease is present in only 1.5-7% of cases 1
• The overall prevalence of WPW with congenital heart disease is approximately 0.45% among all cardiac patients 3

Specific Structural Anomalies Associated with WPW

Ebstein's Anomaly (Most Clinically Significant)

• Ebstein's anomaly is the most important structural association with WPW syndrome, occurring in approximately 25% of Ebstein's patients (5 out of 20 cases in one series) 3
• Right posterior paraseptal accessory pathways are characteristically associated with Ebstein's anomaly 1, 3
• Echocardiography is essential to identify this association, as it significantly impacts management and prognosis 2, 4

Hypertrophic Cardiomyopathy

• Hypertrophic obstructive cardiomyopathy shows association with WPW, with approximately 3.2% of HCM patients demonstrating pre-excitation (7 out of 218 cases) 3
• PRKAG2-related familial WPW presents with cardiac hypertrophy and glycogen storage features, requiring specific echocardiographic evaluation 2, 4
• This genetic form is particularly important to identify due to familial implications and sudden death risk 4

Mitral Valve Abnormalities

• Mitral valve prolapse is documented in WPW patients, appearing in multiple case series 1, 3, 5
• Mitral regurgitation can occur, though typically mild when present 6
• The association appears in both Type II and Type III WPW patterns 5

Congenital Heart Defects

• Atrial septal defects (particularly ostium primum) show association with WPW, with 5 cases identified among 1,348 ASD patients, including 3 with right posterior pre-excitation 3
• Ventricular septal defects demonstrate WPW in approximately 1.4% of cases (3 out of 699 patients) 3
• Isolated cases occur with corrected transposition of great arteries, supravalvular aortic stenosis, aortic incompetence, and patent ductus arteriosus 3

Cardiomyopathies

• Dilated cardiomyopathy shows a 1.62% prevalence of WPW (5 out of 305 cases) 3
• Congestive cardiomyopathy and hypertrophic non-obstructive cardiomyopathy have been documented 5
• Patients with WPW and tachyarrhythmias may develop impaired systolic and diastolic function, which can improve after radiofrequency ablation 7

Clinical Implications and Diagnostic Approach

Mandatory Echocardiographic Evaluation

• Echocardiography is essential in all WPW patients to rule out associated structural heart disease, particularly Ebstein's anomaly, hypertrophic cardiomyopathy, and PRKAG2-related familial WPW 2, 4
• This evaluation is critical before risk stratification and treatment decisions 2

Pattern-Specific Associations

• Type A WPW (left-sided pathways) are primarily NOT associated with specific structural anomalies, as most structural associations involve right-sided pathways 3, 6
• Right posterior paraseptal pathways should raise suspicion for Ebstein's anomaly 3
• Left-sided accessory pathways are more common overall and typically occur in structurally normal hearts 6

Important Caveats

• Pre-excitation can mask ECG findings of underlying structural disease, including right bundle branch block in Ebstein's anomaly, left bundle branch block in aortic incompetence and dilated cardiomyopathy, and myocardial infarction patterns 3
• The presence of structural heart disease increases the complexity of management and may influence ablation strategy 2
• Family history assessment is crucial to identify PRKAG2-related familial WPW, focusing on pre-excitation in first-degree relatives, sudden cardiac death in young family members, and cardiomyopathy 2, 4