Background: Myocardial sleeves extending into the coronary sinus diverticulum (CSD) establish accessory connections between the atrium and ventricle, and result in epicardial pathways that require ablation within the coronary venous system. Accessory pathways associated with CSD are one of the commonest causes of failed ablation.
Objective: To describe the clinical, ECG and electrophysiologic features as well as ablation strategy of accessory pathways associated with CSD.
Methods: Patients with ECG features suggestive of manifest right or left posteroseptal pathways were subjected to coronary venography via a 6F Amplatz catheter advanced from the right femoral vein. A standard electrophysiologic study was then performed in these patients with particular attention to delta wave polarity on the surface ECG and electrogram morphology at the successful ablation site within the CS. While ablating inside the CS, a coronary angiogram was always performed to determine safe distance from the coronary arteries.
Results: Between January 2016 and October 2019, 136 patients with posteroseptal pathways underwent coronary venography. Twenty-two patients had diverticula arising from the proximal CS (mean age 39.2±11 years; 13 females). The mean AH and HV intervals were 65±12.2 and 2.5±13.7 ms, respectively. All pathways demonstrated bidirectional conduction with a mean anterograde and retrograde effective refractory periods of 269.5±62.3 and 226.8±32 ms, respectively. A positive delta wave in lead V1 and a deep S wave in lead V6 were observed in all the patients during sinus rhythm and atrial pacing. A notched, positive QRS in lead V1 (‘M pattern’) was observed in 18 patients, whereas a negative delta wave in lead II was noted in 13 patients. Successful ablation was performed at the neck of the diverticulum in all the patients. None of the patients had complications related to ablation within the coronary venous system. During a follow-up period of 22±17 months, none of the patients had recurrence of preexcitation.
Conclusion: Epicardial accessory pathways associated with CSD have specific ECG and electrophysiologic features allowing early recognition. Ablation at the neck of the diverticula results in the successful elimination of the accessory pathway.