Epicardial Radiofrequency Catheter Ablation in the Coronary Sinus—Truly without Risk?

Objectives: Nowadays, radiofrequency catheter ablation (RFA) of WPW syndrome is safe and highly effective in more than 95% of the patients. However, sometimes endocardial ablation of a posteroseptal or a left posterior accessory pathway (AP) may fail due to an epicardial localization of the AP. These APs often use muscle fibers surrounding the coronary sinus connecting atrial and ventricular myocardium. Those pathways are often noted in patients with a coronary sinus diverticulum. However, side effects of ablation in the coronary sinus still have to be determined in childhood.

Methods: We report approximately two patients with WPW syndrome and a successful RFA in the coronary sinus and in the middle cardiac vein, respectively.

In the first patient (4 years, 18.5 kg) a coronary sinus diverticulum was noted in the preinterventional coronary angiography which is a standard procedure in our institution. In the diverticulum, the earliest retrograde conducted atrial activation during supraventricular tachycardia (SVT) could be localized followed by a successful RFA of the AP using a 5-F ablation catheter. The routine coronary angiography after ablation showed significant reduction of the diverticulum size as a possible result of the coagulation at the diverticulum ostium without any evidence of flow reduction in the coronary sinus.

In the second patient (17 years, 74 kg), enlargement of the middle cardiac vein was noted also after routine coronary angiography. During electrophysiological study, the earliest ventricular excitation in sinus rhythm was noted deep in the middle cardiac vein half of the distance from the AV groove to the LV apex. Subsequently, RFA at this location was successful. During the post interventional course intermittent polymorphic ventricular premature complexes were noted and MRI showed late enhancement in the basal inferior and inferoseptal aspect of the left ventricle. However, 6 months later, ventricular extra beats resolved and a treadmill test showed no ischemic ECG alterations.

Conclusion: In patients with WPW and a posteroseptal or left posterior AP, an epicardial location must be taken into account when endocardial ablation fails. Coronary angiogram may help to identify abnormalities of the venous system of the heart. Epicardal ablation in the venous system should be considered, although it may be associated with a higher risk.

Publication History

Article published online:
21 February 2021