**5. Diagnosis**

164 Congenital Heart Disease – Selected Aspects

TGA for siblings of ccTGA patients is 2.6% with an overall recurrence risk of 5.2% for ccTGA siblings to have some type of congenital heart defect (Piacentini et al., 2005). A recurrence risk of >5% is higher than expected, as the risk is typically thought to be 1-3% for unaffected parents to have an additional child with congenital heart disease (Van der

The natural history of ccTGA depends largely on the presence of associated defects. Patients under 5 years old who also have VSD, LVOTO, and/or TV abnormalities represent the highest frequency of non-surgical deaths. However patients with isolated ccTGA (no associated lesions) may survive into their 4th and 5th decades (Hoffman, 2009; Presbitero et al., 1995). Many patients will demonstrate one or more complications including heart block, tricuspid regurgitation (TR), and congestive heart failure (CHF). Approximately 2-4% of ccTGA patients have ventricular pre-excitation (Wolff-Parkinson-White syndrome) and should undergo radiofrequency ablation of accessory pathways in cases of symptomatic reentrant tachycardia. Atrial tachycardia such as atrial fibrillation and flutter often occur with increasing age, atrial enlargement, and after surgical repair where suture lines and scars may support focal reentrant circuits. By 45 years of age 67% of ccTGA patients with associated defects will have developed CHF, as shown in Figure 2, whereas only 25% of ccTGA patients without associated lesions will have progressed to CHF by this age (Graham et al., 2000). Prieto et al suggests that outcome is dependent on morphology of the TV (the systemic AV valve), as this was the only predictor of severe regurgitation and RV dysfunction in a cohort of ccTGA patients described after mean follow-up of 20 years.

Fig. 2. Freedom from CHF in group I (associated lesions, n=125) and group II (no significant associated lesions, n=50) as a function of increasing age. (Reprinted from *Journal of the American College of Cardiology*, Vol. 36, No. 1, Long-term outcome in congenitally corrected transposition of the great arteries: A multi-institutional study, pp. 255-261, Copyright 2000

Bom et al., 2011).

**4. Natural history and outcome** 

with permission from Elsevier).

Just as the natural history is largely dependent on defects associated with ccTGA, so is timing of presentation and diagnoses.
