Utility of ambulatory monitoring in patients with congenital heart disease.

Patients with congenital heart disease (CHD) are at increased risk of cardiac arrhythmias. The utility of ambulatory (Holter) monitoring in predicting these arrhythmias remains unclear. We sought to evaluate the clinical utility and cost effectiveness of Holter monitoring in patients with CHD. A retrospective study of patients with CHD who had undergone Holter monitoring was performed. The Holter data from patients with tetralogy of Fallot (TOF), d-transposition of the great arteries (d-TGA) after an atrial switch operation, and patients with a single ventricle after Fontan palliation were reviewed. The Holter indication included evaluation of clinical symptoms or as a part of routine screening. The Holter results were deemed clinically significant if they resulted in a change in patient treatment. Sudden cardiac events included death or aborted sudden death and appropriate defibrillator therapies. A total of 589 Holter studies were performed in 189 patients (100 with TOF, 38 with d-TGA, and 51 with Fontan). The results of Holter monitoring performed for clinical symptoms had a low positive predictive value (0.08) for clinically significant changes in management. On routine monitoring, the sensitivity was low (0.40) but the negative predictive value was high (0.96) for future clinically significant arrhythmias. The frequency of clinically significant findings and associated cost-effectiveness improved with older patient age and Fontan and d-TGA CHD type. Nonsustained ventricular tachycardia was associated with sudden cardiac events in patients with TOF but not in those with d-TGA or Fontan palliation. In conclusion, Holter monitoring is generally inefficient for symptomatic evaluation; however, within specific age and CHD type subgroups, such as patients with repaired TOF >25 years old, it could be useful in clinical management and risk assessment as a part of routine care.