I understand you want to make sure your father is safe, especially after his recent heart procedure. Yes, it is generally safe for him to take paracetamol for a fever while taking Preva AS (aspirin). Paracetamol is the preferred choice because other common pain relievers, like ibuprofen, can increase the risk of bleeding when combined with blood thinners. Please ensure he follows the standard dosing instructions for paracetamol and does not exceed the daily limit. If his fever persists or if he feels unwell, please contact his cardiologist or doctor for advice. Wishing him a smooth and steady recovery!