3 | DISCUSSION
To our knowledge this is the first report of CPAF detection in an ESUS
patient with situs inversus totalis. The detection rate of CPAF in ESUS
patients using ICM is 30%.3 However, because the
incidence of SIT is very low in the general
population4 and because the heart and the conduction
system are located on the right side of the body, the safety and
efficacy of ICM in these patients remains unclear. In our experience,
ICM insertion into the right margin of the sternum along the heart
shadow using fluoroscopy is safe and effective for detecting CPAF.
There are three types of ICM devices used in Japan. In the present case
we used the BIOMONITOR III, a novel ICM device that combines a long
sensing vector with a miniaturized profile. Previous studies have
described visible P-waves in >80% of
cases.2 In our case there was no P-wave in the
subcutaneous ECG during AF compared with that during sinus rhythm
(Figure 2A, B). In the subcutaneous ECG recorded by the sudden drop rate
alarm, the P-wave was not visible during AF, but appeared when the
system returned to sinus rhythm. These findings provided a clear
diagnosis of AF rather than sinus tachycardia, and the patient’s
medicine was changed from aspirin to edoxaban. There are several case
reports on the feasibility and safety of catheter ablation for AF with
SIT.5 Thus, if our patient shows drug-refractory AF,
we will consider catheter ablation.