Cognitive Function in Adults with Fontan Circulation Compared with Adults with Acyanotic Congenital Heart Disease: A Pilot Study

Objectives: Impairment regarding their cognitive function is often assumed in adults with congenital heart disease (ACHD). In particular, patients with Fontan circulation are assumed to be at higher risk for impairments in cognitive function. Currently, there is no data with regard to cognitive function formally assessed by standardized intelligence tests in ACHD patients, particularly concerning specific heart defects.

This study analyses the cognitive function in ACHD patients with Fontan circulation compared with patients with acyanotic congenital heart disease (CHD).

Methods: Twenty-eight ACHD patients (female n = 15 (53.6%), mean age at assessment 35.2 ± 13.1 years, Fontan patients n = 14, and acyanotic CHD patients n = 14) underwent the Wechsler Intelligence Scale for adults (fourth edition, German version)—a well-established assessment of cognitive function in adults—between March 2017 and January 2018. Impairment is defined as an intelligence quotient (IQ) achieved less than 1 standard deviation (SD) of the norm (100 ± 1 SD).

Results: Fontan patients achieved a full scale IQ (FSIQ) 102.2 ± 8.9 IQ points (IQp) which was significantly higher than in patients with acyanotic CHD 90.9 ± 11.2 IQp (p = 0.007). Regarding the subcategories, Fontan patients achieved significant higher IQ levels than acyanotic CHD patients in terms of verbal comprehension (107.1 ± 6.8 vs. 94.9 ± 13.1 IQp; p = 0.004) and logical thinking (102.0 ±12.2 vs. 88.9 ± 10.1 IQp; p = 0.005), but not in working memory (100.1 ± 13.8 vs. 93.4 ± 14.0 IQp; p = 0.208) and processing performance (97.1 ± 11.9 vs. 94.1 ± 13.8 IQp; p = 0.554). Both patient groups showed no significant impairment in FSIQ and subcategories IQ levels compared with IQ norm standard (100 IQp ± 1 SD).

Conclusion: In contrast to the general assumption, adult Fontan patients showed normal intelligence levels assessed by IQ test. Interestingly, compared with acyanotic CHD patients, they even achieved significant higher IQ levels in FSIQ and some subcategories in this study. Data from larger cohorts are needed to confirm these findings.