Long-term outcome and exercise capacity in adults with congenital heart disease with focus on tetralogy of Fallot

Sammanfattning: Background: Congenital heart disease (CHD) includes a wide range of malformations, from simple lesions, e.g. ventricular septal defect, that resolve spontaneously, to severe lesions, e.g. univentricular heart, not compatible with life without intervention. Tetralogy of Fallot (ToF) is the most common cyanotic congenital heart disease.In Sweden, approximately 1% of the children are born with CHD each year of which about 30 have ToF. The prognosis has improved remarkably due to advances in surgical techniques as well as peri- and postoperative care. Nowadays, 97% of babies with CHD born in Sweden can be expected to survive into adulthood. Despite huge improvements in prognosis, the relative mortality is still 7 to 97 times higher in patients with CHD, depending on lesion severity, compared with matched controls. Therefore, it is important to improve long-term follow-up and to identify robust and easily available tools to predict poor outcome and optimize timing of possible reinterventions. Addressing quality of life (QoL) has also become more important when survival increases.The main focus of this thesis was on QoL and long-term outcome in patients with repaired tetralogy of Fallot (rToF). In studies I, II and III, we analysed health related quality of life (HRQoL), prevalence of cardiac devices (i.e. pacemakers and implantable cardioverter defibrillators), and exercise capacity, respectively, in patients with rToF. In study IV, the aim was to broaden the perspective and include patients with a wide range of CHD, and to investigate whether exercise capacity, measured as workload could be of help in predicting mortality.Methods: The studies were performed as nationwide register studies. Data from the Swedish registry of congenital heart disease (SWEDCON) were used in studies I-IV. Study II also included data from the Swedish ICD and Pacemaker registry. In studies I-III, only patients with rToF were included, whilst study IV included patient with a broad spectrum of CHD diagnoses.Results: More than half (57%) of the patients with rToF reported best possible HRQoL. New York Heart Association (NYHA) class I and being physically active were associated with best possible HRQoL. Fourteen percent of patients with rToF had a cardiac device, either a pacemaker or an implantable cardioverter defibrillator (ICD). The prevalence of having a cardiac device was lower compared with reports from previous studies, especially for ICDs. Exercise capacity was 75% of predicted in patients with rToF and there was no decline in percent of predicted exercise capacity with age. Low heart rate reserve and low percent of predicted exercise capacity were associated with higher mortality.In study IV, including a wide range of lesions, percent of predicted exercise capacity was associated with mortality. Patients with percent of predicted exercise capacity between 50 and 69.9% had 1.7 times, and patients with exercise capacity <50% of predicted had 2.2 times higher risk of being deceased, over a median follow-up time of 9 years. NYHA class III-IV and ongoing cardiovascular medication were also associated with increased risk of death when adjusted for sex, physical activity and impaired left ventricular function.Conclusions: HRQoL in our patients with rToF was good, despite a fairly high prevalence of cardiac devices. Impaired exercise capacity was associated with an increased mortality. Our results reinforce the need for regular evaluation of exercise capacity in patients with CHD to identify patients at risk of worse outcome. Furthermore, the results in this thesis emphasize the importance of assessing NYHA class and physical activity as part of the follow-up since these parameters are easily attainable and strongly associated with HRQoL and exercise capacity.