Introduction: Striated myocardial connections between the venous wall of the coronary sinus (CS) and the left atrium have been described in humans. This aim of this study was to investigate the conduction properties and potential arrhythmogenicity of CS and left atrial myocardial connections in patients with and patients without paroxysmal atrial fibrillation (PAF).
Methods and results: Thirty-eight patients with PAF, 52 patients with other arrhythmias, and 44 patients without arrhythmia underwent catheter mapping of the CS from the distal superoposterior part to the ostium. Catheterization of the superoposterior CS was feasible in 21, 32, and 25 subjects in the three groups, respectively (P = 0.82). Discrete double potentials or fractionated electrograms were recorded during proximal CS or right atrial pacing in 14 (66.7%), 11 (34.4%), and 5 (20.0%) patients, respectively (P = 0.004). In 29 patients, double or fractionated potentials were recorded at the distal superoposterior CS, in 3 at the mid-CS, and in 4 at the ostium. Spontaneous or induced atrial ectopy and/or tachyarrhythmias were recorded in 18 (85.7%), 12 (37.5%), and 2 (8.0%) patients in the three groups, respectively (P < 0.001) and originated from the CS in 6, 3, and 0 patients, respectively (P = 0.010).
Conclusion: Recording of double potentials is possible within the CS, particularly at its distal superoposterior part, near the left superior pulmonary vein. Their prevalence is higher in patients with PAF than in subjects with other or no arrhythmias, and their presence denotes possible sources or substrate for atrial arrhythmia.