I read your question carefully and I understand your concern.
That episode you are describing could be the result of stroke, luckily the fact that his symptoms have regressed meaning it was perhaps of the type of a
transient ischemic attack, meaning the interruption of blood flow has been restored soon enough not to have left a permanent damage or a small stroke and the damage has been minor. Another possibility is for it to have been a
seizure, but at that age seizures are often a consequence of stroke anyway.
As for the exams a MRI should be performed to look both for a stroke as well as to exclude other reasons like a tumor causing a seizure. If MRI is not promptly available a
CT scan would be useful as well. Don't be surprised if the MRI doesn't show anything, if a transient ischemic attack that could be the case.
What's more important then that though is lowering the risk for a second stroke in the future which could have bigger consequences. The main risk factor in your father's case could be his heart problem which could predispose his heart to create and release clots in the circulation causing stroke. So that's the main issue which should be looked at for which blood thinning products should be given. Also
high blood pressure,
diabetes,
high cholesterol,
smoking should be adressed as well as risk factors for stroke.
Hope things work out for the best, feel free to ask further questions.