IJCS | Volume 32, Nº1, January/ February 2019

42 Nascimento et al. Exercise in adults with congenital heart disease Int J Cardiovasc Sci. 2019;32(1)41-47 Original Article Themost precisemethod to quantify aerobic capacity is the direct measure of peak exercise oxygen consumption (VO 2 max) obtained exclusively by cardiopulmonary exercise testing (CPET). Reduced values of VO 2 max not only indicate more accentuated functional impairment, but also imply an adverse prognosis especially in HF, 21 and also in other clinical conditions including congenital heart diseases in adults. 8-11 The aim of the present study was to describe the level of functional limitation and hemodynamic, ventilatory and metabolic responses to exercise in adults with congenital heart disease referred for CPET in a tertiary cardiology hospital. Methods This was an observational, cross-sectional study that evaluated adults with congenital heart disease (cyanotic or acyanotic), under medical, surgical or percutaneous treatment. The study was approved by the local ethics committee (approval number 47563315.2.0000.5272). All patients were informed about the aim of the study and signed an informed consent form. The study was conducted in accordance with the World Health Organization recommendations and the Helsinki Declaration (October 2013) and the Brazilian National Health Council resolution number 466/2012. Patients referred for CPET between April 2016 and August 2017 were included in this study. Exclusion criteria were: age younger than 18 years, unwillingness to sign the informed consent form, contraindications for CPET according to the Guidelines on Exercise Tests of the Brazilian Society of Cardiology. 22 Cardiopulmonary exercise testing A symptom-limited treadmill (Inbramed ® - Porto Alegre - Brazil) exercise test was performed, using ramp protocol, with duration of approximately eight to 12 minutes. Patients were encouraged to continue exercise until exhaustion. Participants had a minimum of six minute-resting phase, with speed of 1.5 mph and slope of 2.5% in the first minute. For measurements of the gases, a clip was placed on patients’ nose, a mouthpiece with saliva trap was connected to a pneumotachograph which, in turn, was connected to a VO2000 ® gas analyzer (MedGraphics ® - St Paul - USA) coupled to a computer. Analysis was performed using the Ergo PC Elite ® software (Micromed ® - Brasília - Brazil). Every 20 seconds, the following parameters were analyzed in a breath-by-breath format: peak oxygen consumption (VO 2 max), expressed as percentage of the predicted value and related to body mass; 23 oxygen consumption at anaerobic threshold (AT), expressed as percentage of the predicted value and related to body mass; slope of the ratio of ventilation (VE) to CO 2 production (VCO 2 ) (VE/VCO 2 slope); oxygen uptake efficiency slope (OUES), expressed as absolute value and percentage of the predicted value; 24 respiratory exchange ratio (RER); changes in systolic arterial pressure (SAP) from resting to maximal exercise (∆SAP); heart rate reserve (HRR) calculated as heart rate (HR) changes from resting to maximal exercise; chronotropic index (proportion between measured and predicted HRR); HR decrease during the first minute of recovery (HRrec); peak exercise oxygen pulse (O 2 P); circulatory power (CP); ventilatory power (VP). Peak VO 2 was defined as the maximal value detected during the last 20 seconds of exercise or at the first measurement performed during the resting phase. AT was identified by the ventilatory equivalent method, and 40% of the predicted VO 2 max defined as the lower normal limit. 25 VE/VCO 2 slope was calculated during the whole test period. Statistical analysis A descriptive analysis of the data was performed. Categorical variables were described as frequency and percentage, whereas continuous variables as mean ± standard deviation (SD). Data were analyzed using Prism statistics software, version 5.0 (GraphPad Software Inc. La Jolla, CA, USA). Patients were selected by convenience. Results Thirty-one (17 female; 54.8%) adults with congenital heart disease, aged 35.7 ± 14.2 years participated in the study (Table 1). Twenty-seven (87.1%) patients had acyanotic heart disease and the most frequent disease was Tetralogy of Fallot (n = 9; 29.1%) (Table 1). Twenty- four patients had a history of surgery (77.4%), one patient (3.2%) had undergone percutaneous treatment, and six patients (19.4%) were under medical treatment with no history of interventional treatment. The most frequent comorbidities were – systemic arterial pressure (n = 3; 9.7%), dyslipidemia (n = 2; 6.4%), hyperuricemia (n = 2; 6.4%), coronary artery disease (n = 1; 3.2%) and hypothyroidism (n = 1; 3.2%). Medications used by the patients are listed in Table 2.