The effect of tadalafil on functional capacity and echocardiographic parameters in patients with repaired Tetralogy of Fallot

Tetralogy of Fallot (TOF) is one of the most common cyanotic congenital heart diseases (CHD) in children. Various surgical procedures including palliative shunts and TOF total correction (TFTC) were done with some complications, of which, the most common is pulmonary valve regurgitation (PR). Tadalafil is a phosphodiesterase 5 inhibitor which reduces pulmonary vascular resistance, and improves right ventricular function and vascular endothelium, and may have some beneficial effects after TFTC. We studied 18 patients with TOF and PR, with some impaired right ventricular function after TFTC. Tadalafil tablets at a dose of 1 mg per kg (maximum 40 mg) per day as a single dose was administered orally for 8 weeks. In all patients, before and after taking tadalafil, functional class assessment, electrocardiography (ECG) changes, some echocardiographic and endothelial function parameters [flow-mediated dilation (FMD) and intima-media thickness (IMT) of carotid artery], and exercise test were determined. The patient’s mean age was 10.11 ± 4.03 years, and the mean age of operation was 2.52 ± 1.12 years. The effect of tadalafil on different echocardiographic parameters and also on tricuspid valve regurgitation (TR) and PR severity and gradient was not significant. Moreover, it had no effects on QRS duration. Tadalafil had a significant effect on improving FMD and exercise test (P = 0.01). The effect of tadalafil on echocardiographic parameters, carotid artery IMT, and ECG parameters was not significant (P > 0.05). Tadalafil was tolerated well, and the most common side effects were headache and myalgia. This study showed that tadalafil is a safe and well-tolerated drug. It might improve exercise performance, endothelial function, and functional class, and possibly could allow patients a longer period of well-being and could possibly delay the need for pulmonary valve replacement (PVR).