Changes in physical performance after Fontan operation: a follow-up study
Authors: Turquetto A L R , Amato L P , Souza F R , Agostinho D R , Ligeiro M G , Battaglia Filho A C , Alves M J N N , Oliveira P A , Diotto F M , Rondon E , Caneo L F , Jatene M B 
Published: November 2023

Abstract

Background
Maximal oxygen consumption (peak VO2) is markedly compromised in patients with Fontan circulation compared to healthy subjects. In addition to the natural aging process, adaptive mechanisms inherent to univentricular physiology may further contribute to a decline in peak VO2 over time. These patients may have limitations in their ability to engage in physical activity, which may exacerbate the decline in peak VO2. This study aims to quantify the impairment of functional capacity over time in patients in the late postoperative period of Fontan operation and the relationship with a sedentary lifestyle.

Method
We studied 46 patients, 57% female, with a median age of 28 (24 - 35) years and 17 (15 - 21) years after Fontan surgery. Maximum and submaximal variables were analyzed from two standardized cardiopulmonary exercise tests (CPET) on a treadmill and performed with a range of five (4 - 9) years between them. All patients' physical activity levels were ranked using the short version of the International Physical Activity Questionnaire (IPAQ), comparing the functional capacity between active and sedentary patients. Clinical and surgical data were extracted from medical records. We performed a descriptive analysis of the demographic, clinical, and surgical data and a comparative analysis between the variables of the first and second CPET. The annual change was calculated by dividing the differences between the last and first tests by the time interval between them. Maximal variables were analyzed only for patients who achieved a maximum test (respiratory exchange ratio was equal to or greater than ≥ 1.1, heart rate &gt; 85% of the predicted, and signs of intense effort.

Results
Among the 46 patients in the study, 40 performed maximum CPET. The characteristics of patients are shown in Table 1. There was an annual decrease in peak VO2 of 0.42 (1.17- -0.71) mL/kg/min and 0.72 (-2.14 - 0.71) % of predicted VO2. Impaired submaximal parameters occurred in all patients. There was an increased number of sedentary subjects on the second test compared with the first (p=0.009) (Table 2). Comparing the functional capacity of inactive patients with active, we found lower values in peak VO2: 23.1 (20.8-25.1) vs. 35.1 (32.0-35.4) mL/kg/min (p&lt;0.001) and in a percentage of predicted 62 (59-67) vs. 84 (76-97) % (p=0.012). When analyzing the ejection fraction of the systemic ventricle by most recent echocardiogram and brain natriuretic peptide (BNP) plasmatic level, these variables were not significantly changed.

Conclusion
Functional capacity decreased over time in the studied population, represented mainly by a significant annual loss in peak VO2 and the predicted age values. Reduced functional capacity was observed in the inactive patients compared with active. No change in ventricular function was identified, as well as in BNP plasmatic level over time.Table_1Table_2