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............................................................................................................................................................................. sports. Patients with more than mild TR, ventricular dysfunction, shunting, arrhythmias, or other complications should avoid heavy isometric exercises, in proportion to the severity of their problems. • Pregnancy: asymptomatic females with good ventricular function may tolerate pregnancy well. There is a certain risk of RV failure, arrhythmia, and paradoxical embolism. Pregnancy will be of higher risk in the presence of significant cyanosis, serious arrhythmia, and right heart failure (see section 3.5.7). • IE prophylaxis: recommended only for high-risk patients (see section 3.4.6).

4.10 Tetralogy of Fallot

4.10.1 Introduction and background TOF is characterized by the following four features: a nonrestrictive VSD; overriding aorta (but <50%); infundibular, valvular, supravalvular RVOTO and/or branch PA stenosis; and consequent RV hypertrophy (RVH). TOF populations can be subdivided into syndromic patients (20%, such as: microdeletion 22q11, trisomy 21, Alagille, Noonan, Williams, and Klippel Feil) and nonsyndromic patients (which represent the vast majority).230 The standardized mortality rate among patients with repaired TOF is almost twice as high as among patients with simple defects (ASD and VSD).231

4.10.2 Clinical presentation and natural history Surgical repair of TOF has evolved over time, with relief of the RVOTO usually involving infundibulotomy, resection of obstructive muscle bundles, and the use of a patch to enlarge the pathway from the RV to the PAs. In some patients, a palliative shunt procedure  in order to increase pulmonary blood flow  has been performed before repair. Common complications in adulthood are: • PR: significant PR is almost always encountered following a transannular patch repair. PR is usually well tolerated for years. Severe chronic PR, however, eventually leads to symptomatic RV dilation and dysfunction.232 The severity of PR and its deleterious long-term effects are augmented by co-existing distal PA stenoses or PAH. • Residual RVOTO can occur at the infundibulum, at the level of the pulmonary valve and main pulmonary trunk, and into the branches of the left and right PA. Elevated RV pressure and RVH have been described as independent risk factors for poor outcome and a decreased exercise performance, despite smaller RV volumes233. • Residual VSD can be due to partial patch dehiscence or failure of complete closure at the time of surgery; it may lead to LV volume overload. • Aortic complications may occur many years after the initial surgical repair and include progressive aortic dilation and AR (rarely aortic dissection). The underlying mechanism is incompletely understood, and may include ascending aorta dilation, abnormal aortic elasticity, or type of surgical repair234. • RV and LV dysfunction/heart failure: RV dilation is usually due to residual longstanding free PR ± RVOTO. Significant TR may occur as a consequence of RV dilation, which begets more RV dilation. LV dilatation may result from longstanding palliative arterial shunts, residual VSDs, and/or AR. Both RV and LV dysfunction may be due to longstanding cyanosis before repair and/or inadequate myocardial protection during repair, adverse ventricularventricular interactions, electromechanical dyssynchrony,235,236 and coronary artery abnormalities. A reduced LV free wall longitudinal strain has been reported despite preserved LVEF.237 The incidence of clinical heart failure, with its typical signs and symptoms, increases significantly with age.238

Underlying mechanisms may also be: damage to myocardium, sequelae from surgical repair strategies, or electrical conduction abnormalities. Management strategies effective in acquired heart disease are frequently applied in these patients, although its effectiveness for RV failure remains uncertain.239 • Atrial/ventricular arrhythmias and SCD: arrhythmias and sudden death are important late complications. The estimated lifetime prevalence of atrial arrhythmias is 20%. IART involving the cavotricuspid isthmus and RA incision are related to RA enlargement, whereas AF is facilitated by LA dilatation. Ventricular arrythmias encompass polymorphic VT/VF, typically related to severely impaired RV and LV function, and monomorphic sustained VT, which are particularly relevant in rTOF.34 Although both polymorphic VT/VF and monomorphic VT can lead to SCD, with a reported frequency of 13.5% in retrospective studies,32 the different underlying ventricular arrhythmia substrates need to be recognized for risk stratification and treatment. LV systolic or diastolic dysfunction, and ventricular and atrial tachyarrhythmias are predictive of death and sustained VT in adults with rTOF.240 Possible risk factors associated with any ventricular arrhythmia and SCD in rTOF are QRS duration >_180 ms, LV systolic or diastolic dysfunction, and inducible VT at EP testing. Older age at PVRep and pre-PVRep RVH and dysfunction may be predictive of shorter time to post-operative death and sustained ventricular arrhythmia.241 The dominant substrates for monomorphic VT are anatomically defined isthmuses, bordered by unexcitable tissue. Isthmus dimension and conduction properties can be evaluated by catheter mapping and likely determine susceptibility to arrhythmias. Targeting the anatomical isthmuses by catheter ablation has been highly effective to control VT.242 Whether catheter mapping can contribute to individualized risk stratification requires further investigation. • Endocarditis can be encountered after both surgical and percutaneous PVRep. Valve-containing prosthetics are an important independent risk factor for IE in the short- and long-term after implantation, whereas non-valve-containing prosthetics are a risk factor only during the first 6 months after implantation.76 A schematic overview of long-term complications after repair of TOF is provided in Figure 8.

4.10.3 Diagnostic work-up of repaired patients See section 3.3 for general principles. • Clinical findings mostly include a wide split in the second heart sound. A low-pitched early ending diastolic murmur suggests severe PR. A long, loud ejection systolic murmur indicates RVOTO, a high-pitched diastolic murmur indicates AR, and a pansystolic murmur indicates a residual VSD. Downloaded from academic.oup.com/eurheartj/article/42/6/563/5898606 by guest on 07 October 2026