Abstract 11413: Appearance of QRS Fragmentation Late After Atrial Switch Repair for d-Transposition of the Great Arteries is Associated With Adverse Clinical Outcome

Abstract

Introduction: The extent of myocardial fibrosis on magnetic resonance imaging (MRI) in the systemic right ventricle (RV) of adults after atrial switch repair for d-transposition of the great arteries (d-TGA) correlates with outcome. However, MRI is costly and access is limited. Fragmented QRS (fQRS) on a 12-lead electrocardiogram (ECG) reflects inhomogeneous ventricular activation. It is considered to be a surrogate for fibrosis and related with outcome in ischemic cardiomyopathy. Hypothesis: Appearance of fQRS during follow-up is a predictor for adverse events in adults after atrial switch repair for d-TGA. Methods: Records of adults with atrial switch repair for d-TGA were retrospectively reviewed in the database of a tertiary care hospital. Exclusion criteria were systemic RV assist device or heart transplantation (HTx) before the age of 16 years, or fQRS already present at transfer from the pediatric department. One blinded reader analyzed all available ECGs to detect fQRS. fQRS, severe tricuspid regurgitation (TR), severe RV dysfunction and severe RV dilatation were modeled as time-dependent covariates. Cox regression was performed to assess the relationship between covariates and (1) the composite endpoint of cardiovascular mortality, HTx or systemic RV assist device, and (2) worsening RV function. Results: Records of 89 patients (34% female, 42% Mustard repair) were analyzed. Patients underwent atrial switch repair between Oct 1969 and Nov 1992. At latest follow-up, fQRS was noted in 26 patients (29%), most frequently inferior (92%). Over a median follow-up of 16.9 (IQR 12.6-22.9) years, the composite endpoint occurred in 9 patients (10%). In multivariate Cox analysis, appearance of fQRS (HR 14.11; 95% CI 1.42-140.12) and development of severe RV dysfunction (HR 11.36; 95% CI 2.08-62.17) were significantly associated with the composite endpoint. Moreover, appearance of fQRS was significantly associated with worsening RV function (HR 2.66; 95% CI 1.18-6.01), independently of development of severe TR. Conclusions: Appearance of fQRS is associated with adverse clinical outcome and worsening RV function in adults after atrial switch repair for d-TGA. It might become an easily implementable tool to identify patients at risk for adverse events.