New electrocardiographic criteria for the differentiation between counterclockwise and clockwise atrial flutter: correlation with electrophysiological study and radiofrequency catheter ablation

Objective-To develop new electrocardiographic (ECG) criteria for the differentiation between counterclockwise and clockwise atrial flutters. Background-Traditionally, the ECG differentiation between counterclockwise and clockwise atrial flutters is based on the nutter wave polarity in the inferior leads. However, determination of nutter wave polarity is subjective and sometimes difficult, especially in nutter waves of undulating pattern. Patients-The study comprised 37 consecutive patients with drug resistant atrial nutter; 30 had counterclockwise and 17 had clockwise atrial nutter (10 had both forms of atrial nutter). The isthmus dependence was confirmed by entrainment study and catheter ablation. The ECG patterns of both types of atrial nutter were compared and the nutter wave polarity in the inferior leads was determined by four independent cardiologists. Results-The nutter wave polarity in the inferior leads appeared negative in 24, positive in one, and equivocal in five of the counterclockwise atrial flutters; polarity appeared negative in one, positive in 10, and equivocal in six of the clockwise atrial flutters. However, the aVF/lead I nutter wave amplitude ratio was > 2.5 in all counterclockwise but < 2.5 in all clockwise atrial flutters. The nutter wave nadirs in the inferior leads corresponded to the upstrokes in V1 in all counterclockwise atrial flutters, but corresponded to the downstrokes in V1 in all clockwise atrial flutters. Conclusions-The nutter wave polarity in the inferior leads does not correlate well with the nutter wave rotating direction. However, counterclockwise and clockwise atrial flutters can be differentiated by new ECG criteria with high accuracy.