Méc sin de base

French to English Medical Medical (general) Holter report

Good evening everyone,

This is part of a Holter report interpretation.

Méc sin de base leg bradycarde FC moy 57/min
ESA et ESV occ.
Rare triplets ESV
Courtes TAP max 8 batt.
Pas de longue pause ou bradycardie profonde

sin de base is perhaps "baseline sinus rhythm?"
leg bradycarde (yes that is how it's spelled) would be "mild bradycardia"

The only word that comes to mind for méc is "mechanism" but I'm not sure how it would fit here.

Would anyone be able to help?

Thanks!