Percutaneous catheter ablation of atrial fibrillation in a patient with an anomalous pulmonary venous connection

A 62-year-old patient was referred for the treatment of highly symptomatic and drug-resistant paroxysmal atrial fibrillation (AF). First AF paroxysm occurred as early as 1992. At that time, patient was diagnosed with a partial anomalous pulmonary venous connection (PAPVC) without atrial septal defect (ASD). Now repetitive Holter monitoring revealed paroxysms of sustained AF. Transthoracic echocardiogram showed a right ventricular end-diastolic diameter of 44 mm, a systolic pulmonary arterial pressure of 52 mmHg, and a shunt ratio of 2.13. Left atrial (LA) diameter (PS-LAX) was 41 mm. Right atrium (RA) was dilated with a surface area of 24 cm2. Surgical repair of the anomalous pulmonary veins (PVs) was found not to be appropriate due to the absence of progressive haemodynamic impairment. Segmentation of a pre-acquired computed tomography (CT) (Carto Software) confirmed a connection of the right superior PV and right middle PV (RMPV) to the superior vena cava (SVC) just superior to the junction with RA (left panel). The right inferior PV (RIPV) and a left common PV (LCPV) connected normally to the LA. The ablation procedure was started with CT-integrated electro-anatomical mapping of the LA (55 mL) and RA (129 mL) using a 3.5 mm irrigated-tip catheter (ThermoCool, Biosense Webster, Diamond Bar, CA, USA). Mapping within RMPV and RIPV (from within RA) revealed no electrical activity during sinus rhythm (also not after isoprenaline). Only just proximal above the RA–SVC junction, a sharp SVC ‘sleeve’ venous potential (right panel) was recorded. Induction of AF was not attempted. The ablation procedure (middle panel) consisted of Lasso-guided electrical isolation of the LCPV and RIPV from within LA [radiofrequency (RF) time 22 min, 48°, 20–35W] and segmental isolation of the SVC (RF time 4 min, 48°, 35W). Until the last follow-up (12 months after ablation), patient was free of symptomatic AF without anti-arrhythmic drugs and 7-day Holter monitoring did not reveal AF. This case report illustrates the feasibility of performing successful catheter ablation of AF in a patient with drug-resistant paroxysmal AF, despite underlying APVC. Partial APVC is a rare congenital defect found in ∼0.5% of autopsies.1,2 In PAPVC, one or more of the PVs (mostly right-sided) return to the RA with a frequent association of ASD.1,2 Over many years, excessive PV return to the right side of the heart might cause right atrial and ventricular dilatation, eventually resulting in increased likelihood of arrhythmias (mainly AF). Atrial fibrillation in PAPVC might be due to non-specific remodelling of the atria (due to atrial stretch) or due to an increased arrhythmogenic substrate of the (abnormally connected) PVs. Faced with a patient with PAPVC, one could withhold catheter ablation because of the complexity of the anatomy and the likelihood of non-PV-mediated AF. This case report, however, demonstrates that a ‘classic’ PV isolation of the normal ‘left-sided’ PVs combined with SVC isolation can result in a high clinical efficacy with persistence of sinus rhythm at long-term follow-up. In this particular case, it is difficult to estimate the incremental benefit of SVC isolation. Mapping within the anomalous PVs suggests the absence of myocardial sleeves extending into these PVs. On the other hand, SVC isolation (on top of the PV isolation) is known to improve the clinical outcome.3 Conflict of interest: none declared.