Incidence and Clinical significance of ATP-induced AF
Previous studies reported that the incidence of ATP/Adenosine-induced AF
was 29.6 and 47% before PV isolation;7, 8 and 5.6 to
13% after PV isolation.9, 10, 11 Most of these foci
located in PV and SVC. When excluding non-PV/non-Box and non-SVC foci,
the incidence of ATP-induced AF was 2.5% and 15% before PV isolation;
and 2.4% to 7.4% after PV isolation in these studies. These were still
higher than the incidence of the present study.
The difference in the incidence of ATP-induced AF from non-PV foci was
mainly due to various induction protocols. Tutuianu et al. used
adenosine of 18 or 36 mg for induction,8 equivalent to
about 34 or 68 mg of ATP according to each molecular weight. The
excessive dose may lead to provoke non-clinical and non-specific
triggers. The dose of ATP and isoproterenol in the present study was
lower than previous studies because the purpose of ATP injection was to
unmask dormant conduction between LA and the isolated areas, not to
induce AF.
Tutuianu et al. also reported that adenosine much more frequently
induced non-PV triggered AF as compared with ISP (3 to 20 mcg/min);
then, they concluded that there was no correlation between non-PV
triggers with ATP and arrhythmia recurrence.8
In contrast, Kuroi et al. administered 30 mg of ATP after PVI and
identified that ATP-provoked AF originating from the atria (not from
SVC) was the independent predictor of a recurrence of arrhythmia even
after the repeat procedure.10
Tao et al. administered 20 mg of ATP before PVI, and they revealed that
ATP-induced AF was documented from the same site as the spontaneous AF
in 41% of patients.7
Similar to the incidence of AF induction, the difference in the
induction protocols might lead to a discrepancy in the clinical
significance. The different patient populations and a limited number of
cases who undergo the repeat procedure to confirm the relationship
between the AF recurrence and the ATP-provoked foci also might be
related to the discrepancies.
In our study patients, only 20 mg of ATP injection following PV/Box
isolation (and SVC isolation in 4 of 7 patients) reproducibly induced
AF. Therefore, mapping and ablation of non-PV/non-Box foci were thought
to be mandatory, and the ablation resulted in favorable clinical
outcomes.