P2.006: P-wave Indices and Clinical Predictors of Atrial Arrhythmia in Repaired Tetralogy of Fallot

Background: Adults with repaired Tetralogy of Fallot (TOF) are at risk for late-onset atrial arrhythmias. Identifying predictors is essential for risk stratification and clinical management. This study aimed to describe demographic and clinical characteristics and identify independent predictors of atrial arrhythmias in cohort of repaired TOF patients.

Methods: We retrospectively studied 133 adults with repaired TOF (mean age ≈ late 30s, 55% male) who had no prior atrial arrhythmias at baseline. ECG analysis was performed on up to three serial ECGs per patient (initial postoperative ECG and two subsequent follow-ups). P-wave indices assessed included P-wave dispersion (difference between maximum and minimum P-wave duration across leads), PTFV1 duration (ms of terminal negative P-wave in lead V1), the negative P-wave area in V1, and total P-wave terminal force. Clinical data (age, sex, comorbidities, New York Heart Association (NYHA) functional class, etc.) were collected. Incident atrial arrhythmias were tracked during long-term follow-up. Univariate analysis identified factors associated with arrhythmia development, and a multivariable logistic regression was constructed to determine independent predictors (odds ratios with 95% confidence intervals).

Results: The cohort was predominantly Caucasian (56.4%), with 61.7% undergoing pulmonary valve replacement (PVR). Most initial repairs (78%) were transannular patches, and 36.8% had prior shunts. Repairs occurred primarily in infancy (52%). Atrial arrhythmias developed in 14.3% (mean onset age 35.7±13.1 years), typically around 30 years post-repair.

Univariate analyses showed significant associations between atrial arrhythmias and older age (45.7 vs. 35.1 years, p=0.008), hypertension (31.6% vs. 8.8%, p=0.012), smoking history (31.6% vs. 7.0%, p=0.006), obstructive sleep apnea (26.3% vs. 3.5%, p=0.003), coronary artery disease (10.5% vs. 0%, p=0.019), heart failure (42.1% vs. 5.3%, p< 0.001), and higher NYHA functional class II/III (52.6% vs. 5.3%, p< 0.001). ECG analysis demonstrated significantly prolonged negative P-wave terminal force duration in lead V1 (PTFV1 duration) in those developing arrhythmias (79.8 ms vs. 62.9 ms, p=0.006).

Multivariate logistic regression identified obstructive sleep apnea (OR 15.63, 95% CI 1.68–145.7; p=0.016), NYHA class II (OR 11.8, 95% CI 1.15–121.6; p=0.038) and III (OR 41.9, 95% CI 1.23–1432; p=0.038), and prolonged PTFV1 duration (OR 1.03 per ms, 95% CI 1.00–1.06; p=0.032) as independent predictors of arrhythmia.

Longitudinal ECG analysis demonstrated dynamic changes: arrhythmia patients exhibited increasing P-wave dispersion preceding arrhythmia onset and initially elevated but progressively decreasing PTFV1 metrics, suggesting atrial electrical remodeling. In contrast, non-arrhythmic patients maintained stable ECG parameters throughout follow-up.

Conclusion: In repaired TOF patients, atrial arrhythmias are relatively common late complications, typically occurring decades post-repair. Longitudinal ECG changes, notably increasing P-wave dispersion and initial atrial conduction abnormalities, may precede clinical arrhythmia onset, indicating potential early warning signs. These findings support close monitoring of high-risk individuals and targeted interventions such as timely valve replacement and aggressive management of modifiable risk factors to mitigate arrhythmia risk.