The use of crista terminalis maximum interdeflection time for right-left determining in atrial flutter patients

Although surface electrocardiography (ECG) provides important information about the localization of atrial flutter (Afl), in cases where the p wave is unclear, it may not provide enough information about the ablation strategy and the procedure time may be prolonged. This study aimed to investigate the potential utility of crista terminalis double split signals in the differentiation of right- versus left-sided Afl in patients undergoing ablation therapy. In this retrospective study, symptomatic patients with Afl diagnosed by surface ECG and in whom no thrombus was detected by transesophageal echocardiography were enrolled. The decapolar catheter was placed into the crista terminalis and coronary sinus. The two most distant split signals were recorded as 'maximum interdeflection time' (MIT) in crista terminalis. The right or left atrium was mapped with 3-D system. 3-D mapping identified 112 patients with right Afl and 32 patients with left Afl. The right atrium was found to be significantly increased in patients with right Afl, whereas the left atrial diameter (LAD) was found to be significantly increased in patients with left Afl. The number of patients with coronary sinus activation sequence from proximal to distal, coronary sinus proximal to distal interval time and MIT were significantly increased in patients with right Afl. When patients with MIT > 80 ms and coronary sinus activation sequence from proximal to distal were taken together, it was found that the distinction between right and left atrial flutter was perfectly distinguished. In conclusion, MIT may serve as a valuable adjunctive parameter for distinguishing right- from left-sided Afl prior to 3-D mapping.