Long-term follow-up of patients with inducible supraventricular tachycardia treated with flecainide or propafenone: Therapy guided by transesophageal electropharmacologic testing

We report our experience with flecainide and propafenone therapy for inducible supraventricular tachycardias and paroxysmal supraventricular tachycardias due to atrioventricular (AV) nodal reentry or the Wolff-Parkinson-White syndrome. We performed an electropharmacologic test (ET) that consisted of first inducing a clinical arrhythmia by transesophageal atrial pacing (TAP) protocol. This was followed by intravenous drug administration and TAP reevaluation, either after acute intravenous administration or in oral steady-state. We used ET with flecainide and/or propafenone to study 2 groups of patients at least 3 years before the long-term clinical observation period. The first group was comprised of 58 patients with reciprocating tachycardias—due to AV node reentry in 17 (29.3%) and anomalous pathway in 41 (70.7%). Twelve (29.3%) of the latter had reciprocating tachycardias, 15 (36.6%) had atrial fibrillation, and 14 (34.2%) had both arrhythmias. During ET, flecainide was administered to 42 patients, and the ET was considered positive in 28 (66.7%). Propafenone was administered to 32 patients, with positive results in 15 (46.9%). In 15 patients, both flecainide and propafenone were tested, 8 receiving flecainide after a negative ET with propafenone, and 7 receiving propafenone after a negative ET with flecainide. In the first group, the ET was positive in 7 (87.5%), and in the second group, it was positive in 3 (42.9%). In a follow-up of 40.1 ± 11 months, 38 (65.5%) patients had positive outcomes, 5 (8.6%) had to stop receiving the drugs because of side effects, 3 (5.2%) stopped because of inefficacy, and 12 (20.7%) dropped out. The second group was comprised of 30 patients who had disabling supraventricular reciprocating tachycardias due to anomalous pathway in 25 (83.3%) cases and AV node reentry in 5 (16.7%) cases. In this group of patients, propafenone and/or flecainide were sequentially administered after either inefficacy or paradoxical effect of the first drug. Propafenone was administered to 13 (43.3%) patients after flecainide, with positive results in 6 (46.2%) cases, and flecainide was administered to 17 (56.7%) patients after propafenone, with positive results in 10 (58.8%) cases. We conclude that flecainide and propafenone are useful antiarrhythmic drugs in long-term prophylaxis of inducible supraventricular tachycardia in ET responder patients. ET by TAP allowed us to identify immediately either “responder” patients or “nonresponder” patients