Cryoablation can be used to treat atrial fibrillation (AF) surgically. We describe a 71-year-old woman who underwent cryoablation after 6 months of AF. Four hours post-surgery, electrocardiographic changes were observed in the circumflex artery territory associated with hemodynamic instability, which responded to inotropic agents. Angiography revealed a diffuse circumflex artery spasm with a heterogeneous aspect of the posterior branch evoking a dissection. Platelet anti-aggregant and trinitrine therapy were started. Recovery was uneventful and the patient was discharged on day 13. Cryoablation-associated circumflex artery dissection is rare. Caution is required when locating the ablation lines to avoid coronary artery injury.