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.................................................................................................................................................................... a1-antitrypsin levels in the stool.310 It has traditionally been associated with a very poor prognosis (5-year survival <50%) but a more recent study reported a 5-year survival of 88%; however, treatment remains challenging.311 Plastic bronchitis and lymphatic system dysfunction may further complicate prognosis.

For more details, see a recently published extensive review.312

4.16.3 Diagnostic work-up See section 3.3 for general principles. Clinical findings include commonly mild, non-pulsatile jugular venous distension. Significant jugular venous distension and hepatomegaly, however, raise suspicion of Fontan obstruction or ventricular failure. ECG frequently shows junctional rhythm or atrial arrhythmias. Pleural effusion on chest X-ray raises suspicion of protein-losing enteropathy. • Echocardiography is the first-line diagnostic tool, providing information on ventricular and valve function. To image the Fontan pathway, TOE or other imaging modalities are generally required. • Annual blood tests should include haematology, serum albumin, and liver and renal function. When protein losing enteropathy is suspected, a1-antitrypsin clearance must be calculated. • CMR is helpful for evaluation of the Fontan pathway, collaterals, and pulmonary veins (e.g. right pulmonary vein obstruction by enlarged RA) and for thrombus, all of which CCT can also provide. CCT requires experience to mitigate streaming artefact and false positive diagnosis of thrombus. CMR is regularly performed for ventricular volumes, Fontan pathway patency and flows, to evaluate AV valve regurgitation, subaortic obstruction, myocardial fibrosis, and for detection of thrombus. • As liver dysfunction, liver cirrhosis, and hepatocellular carcinoma have been recognized as typical complications in this setting, regular liver imaging (ultrasound, computed tomography, magnetic resonance) and laboratory assessment should be performed. • Cardiac catheterization should be performed at a low threshold in cases of unexplained oedema, exercise deterioration, newonset arrhythmia, cyanosis, and haemoptysis. It provides information on ventricular and valvular function, haemodynamics including PVR, and Fontan obstruction and anomalous vascular connections (see section 4.16.2). Integration with CMR for flows (cardiac output) may allow more precise measurement of PVR.

4.16.4 Medical treatment

• Anticoagulation: right atrial blood stasis and disturbed coagulation may predispose to thrombosis. The potential for subclinical, recurrent pulmonary embolism (eventually leading to a rise in PVR) and systemic embolism have led to a recommendation, by some, for lifelong anticoagulation. There is, however, no evidence of benefit, and practice varies between centres. Anticoagulation is indicated in the presence, or with a history, of atrial thrombus, atrial arrhythmias, or thromboembolic events. Although NOACs have been reported to be safe in selected Fontan patients,79 robust prospective efficacy data are lacking and thus these drugs cannot currently be recommended as standard therapy. • Antiarrhythmic therapy: loss of sinus rhythm may precipitate rapid haemodynamic decline and atrial arrhythmias. Sustained atrial arrhythmia with rapid AV conduction should be considered a medical emergency. Electrical cardioversion is the mainstay of treatment, as drug therapy is often ineffective. Amiodarone may be effective in preventing recurrence, but it has many long-term side effects. Sotalol can be an alternative. There should be a low threshold for radiofrequency ablation, although these are difficult arrhythmias to treat in the catheterization laboratory.313

Antitachycardia atrial PMs may assist. If AV pacing is required, this will need an epicardial approach. Occurrence of arrhythmias should prompt haemodynamic evaluation. In addition, a proactive approach of EP evaluation and ablation therapy (where appropriate) should be considered, including Fontan conversion with concomitant arrhythmia surgery. ICD therapy may be considered in selected patients. See section 3.4.2. • Therapy of protein losing enteropathy: medical therapy remains challenging and various treatments have been proposed (after exclusion of haemodynamic problems) including salt restriction, high protein diet, diuretics, ACE inhibitors (may be poorly tolerated), steroids, albumin infusion, chronic subcutaneous heparin, creation of a fenestration (by interventional catheter), and eventually, consideration of transplantation. • Pulmonary vasodilators: ERAs and PDE-5 inhibitors may be considered in selected patients with elevated pulmonary pressure/ resistance in the absence of elevated ventricular end diastolic pressure. Data on the routine use of these medications in Fontan patients are limited at present. A randomized trial of the ERA bosentan has demonstrated significantly improved cardiopulmonary exercise capacity in 75 adults with Fontan physiology.314

4.16.5 Surgical/interventional treatment Patients with a ‘failing Fontan’ (with a combination of intractable arrhythmia, right atrial dilation, worsening AV valve regurgitation, deterioration of ventricular function, and/or atrial thrombus) should be considered for surgery.315 While patients with failing systemic ventricular function may benefit from heart transplantation (performed in experienced settings), patients with preserved systemic ventricular function, atrial arrhythmia, and impaired flow dynamics in the Fontan pathway may benefit from conversion to extracardiac total cavopulmonary connection and concomitant cryoablation.316 The latter has provided good early results in a very experienced setting, but is associated with surgical mortality and ongoing morbidity, with the need for both continued drug therapy and pacemaker implantation in the majority of cases.317 If performed late, conversion may be less likely to result in a good outcome, and cardiac transplantation may be required. However, the best timing for a conversion remains a matter of uncertainty. In selected adult patients, it may be appropriate to consider device closure of a fenestration if there is significant cyanosis, but this may also worsen the patient’s condition. Catheter intervention may also be required in the case of flow obstruction, or anomalous vascular connections. Downloaded from academic.oup.com/eurheartj/article/42/6/563/5898606 by guest on 07 October 2026