Coronary sinus signal amplitude predicts left atrial scarring

Left atrial scarring is recognised as a critical component in the maintenance of atrial fibrillation and is associated with the failure of interventional treatment. Diminished bipolar voltage (LV) has been proposed as a useful tool for left atrial scar quantification. We hypothesised that, due to its anatomic location, signals on the coronary sinus catheter might be used to predict the amount of left atrial low voltage.

A total of 124 patients (42% women, average age 66 ± 9 years) were included. Forty-one with paroxysmal and 83 with persistent atrial fibrillation. Left atrial low-voltage (<0.5 mV, measured during sinus rhythm) area size and distribution varied considerably among the included patients (mean: 34.9%; maximum: 94.6%; minimum: 0.4%). Spearman correlation revealed a strong negative correlation between bipolar voltage of the signals on the coronary sinus catheter and the amount of left atrial scarring (R = -0.778, p < .0001). The optimal CS voltage cut off for prediction of left atrial low-voltage size of ≥50% was 1.9 mV with an area-under-the receiver-operating-characteristic (ROC) curve of 0.982, a sensitivity of 97% and a specificity of 98%.

There is a strong negative correlation between the size of left atrial low-voltage areas (LVA) and coronary sinus signal amplitude. With increasing left atrial LVA size, CS signal amplitudes decrease, and vice versa. On the basis of these findings, average CS signal amplitudes of ≤1.9 mV can be used as a predictor for a left atrial low-voltage size of ≥50%.