Severe Arrhythmic Events in Patients with Complex Congenital Heart Disease on Long-Term Follow-up

Objective: To describe the occurrence of severe arrhythmic events in patients with complex congenital heart disease.

Methods: Medical charts were reviewed from 677 patients with complex congenital heart disease (CHD). Primary end points were sudden cardiac death (SCD), aborted SCD, appropriate implantable cardioverter-defibrillator (ICD) discharge, ICD antitachycardia pacing (ICD-ATP) for ventricular tachycardia (VT), hospital admission for acute ventricular arrhythmias, cardiac syncope caused by ventricular arrhythmia, and the occurrence of nonsustained or sustained VT (nsVT, sVT) on Holter, pacemaker, or ICD read within a follow-up time of 3 years. The secondary outcome severe arrhythmic event (SAE) was a composite of primary outcomes.

Results: We included 501 patients (274 males) in the study. Age at last follow-up was 29.2 ± 11.2 years. Underlying diagnosis was univentricular heart (UVH) in 90 patients, Ebstein’s anomaly in 43 patients, tetralogy of Fallot (TOF) in 197 patients, common arterial trunk in 26 patients, and transposition of the great arteries who underwent arterial switch operation in 69 patients or Senning/Mustard procedure in 76 patients. The table shows the occurrence of primary and secondary outcomes. UVH patients presented with an increased long-term risk of experiencing SAE (p = 0.008) compared with other CHD. Higher age correlated with an increased occurrence of SAE in UVH (age at follow-up [years] 29.7 ± 9.1 vs. 22.8 ± 9.9, p = 0.01, patients with SAE vs. without SAE) and TOF (age at follow-up [years] 33.6 ± 13.0 vs. 26.4 ± 11.0, p = 0.005, patients with SAE vs. without SAE).

Conclusion: Severe arrhythmic events are frequent in adult patients with complex CHD, especially with UVH physiology. Older age correlated with higher risk of severe arrhythmias in patients with UVH and TOF. Thorough risk stratification is required in this patient population.

N/n (%)	SAE	SCD or equivalent	Syncope or hospital admission for arrhythmia	nsVT or sVT in device	ICD
Legend: SCD or equivalent: SCD, aborted SCD, appropriate ICD discharge, ICD-ATP; ICD: patients with ICD during follow-up.
Univentricular heart	17/90 (18.9)	2/90 (2.2)	3/90 (3.3)	16/90 (17.8)	2/90 (2.2)
Ebstein´s anomaly	4/43 (9.3)	1/43 (2.3)	1/43 (2.3)	4/43 (9.3)	1/43 (2.3)
Tetralogy of Fallot	22/197 (11.2)	2/197 (1.0)	7/197 (3.6)	17/197 (8.6)	11/197 (5.6)
Common arterial trunk	0/26 (0.0)	0/26 (0.0)	0/26 (0.0)	0/26 (0.0)	0/26 (0.0)
Transposition of the great arteries (art. switch)	7/69 (10.1)	0/69 (0.0)	3/69 (4.3)	4/69 (5.8)	2/69 (2.9)
Transposition of the great arteries (Senning/Mustard)	5/76 (6.6)	1/76 (1.3)	1/76 (1.3)	4/76 (5.3)	2/76 (2.6)
Total	55/501 (11.0)	6/501 (1.2)	15/501 (3.0)	45/501 (9.0)	18/501 (3.6)