Patent as stated before means open ie blood is getting through to the heart (im assuming its the heart we’re talking about as one of your tags is cardiology).
If the exact wording they used was “possibly patent” it might mean that they did not get enough images to tell if the artery was blocked or not. As everything is moving during the image capture you some times don’t get the perfect views you would hope for.
you should go and discuss this with your cardiologist
It might not be anything to worry about and probably isn’t but you really need to talk to them about it.
For everybody else if you are having test xrays or any other interaction with a doctor/nurse what ever and they say something you dont understand or are not clear about ask them to explain. They wont mind. You are afterall paying them and probably paying them well.