Detection of fractionated signals in stable arrhythmias

In an example, a method includes receiving a cardiac signal that is sensed by an electrode at a tissue location inside the heart. Fractionations are identified in the cardiac signal. The fractionations identified at the tissue location are compared between first and second cardiac cycles of the cardiac signal. Based on the comparing, a likelihood is estimated, that the tissue location is causing a stable arrhythmia. Based on the estimated likelihood, the tissue location is indicated to a user as likely to be causing the stable arrhythmia.