Background

The atrial switch operation (Mustard or Senning procedure) was the first successful treatment option for children with transposition of the great arteries (TGA). In this patient cohort, the right ventricle is the subaortic and hence systemic ventricle. This leads to a significant morbidity and mortality already in the first four decades of life. Nonetheless, a substantial proportion of patients are nowadays reaching the 5^th decade of life. However, data regarding these older patients (over the age of 40 years) is lacking.

Methods

TGA patients over the age of 40 years under active follow-up between January 2005 and December 2019 were included. Demographic data, as well as medical/surgical history, were retrieved from hospital records. The primary endpoint was a major adverse cardiovascular event (MACE), defined as combined endpoint of hospitalization due to cardiac reasons, arrhythmias or death. All-cause mortality was the secondary endpoint.

Results

Altogether, 96 patients (mean age 40.8 ± 1.0 years, mean age at atrial switch 3.0 ± 2.9 years, female 37.5%) were included. Out of these, 73 (76%) patients had a Mustard operation and 23 (24%) a Senning operation.  Most common associated lesions were ventricular septal defects (n=36, 37.5%) and obstructions of the subpulmonary left ventricular outflow tract (n=28, 29.2%). At baseline, a pacemaker was present in 29 patients (30.2%) and an ICD in 5 (5.2%). At baseline, a history of atrial arrhythmias was found in 41 patients (42.7%) and of ventricular arrhythmias in 6 (6.3%).

During a median follow-up of 3.8 years (IQR 1.8-7.2), MACE occurred in 53 patients (55.2%). On univariate analysis, moderate-severe reduced systemic ventricular function, history of atrial arrhythmias, history of ventricular arrhythmias, and the presence of a pacemaker were predictors of MACE. Upon multivariate analysis, moderate-severe reduced systemic ventricular function (HR: 3.01, 95% CI: 1.57–5.78, p < 0.001) and the presence of a pacemaker (HR: 1.89, 95% CI: 1.02–3.50, p = 0.045) remained as independent predictors of MACE. During follow-up, five patients (5.2%) died. On univariate analysis, a predictor for the secondary endpoint could not be identified.

Conclusions

TGA patients after the atrial switch are burdened with significant morbidity and mortality even after the 4^th decade of life. The presence of a pacemaker as well as a reduced systemic ventricular function are predictors of MACE.