There are translation services to help non-English speaking patients during their treatment and care - we quite often book translators for our patients during their visits to the department, for instance.
I take it you are referring to translation of French medical reports in your possession? To begin with, a lot of the clinical data, let's say blood results or ultrasound reports, will be readily understood by your cardiologist or other doctors without translation. In addition many French medical terms are easily translatable into English by a doctor that is familiar with the speciality concerned.
In reality it is likely that the doctors will take a history, use the French data to inform that history-taking, and then carry out their own investigations.
[Edit: in my experience of situations in which patients arrive with medical reports in another language, there is always someone in the hospital who can translate, especially if it is in a European language. It's quite common to put an email request out and most hospitals maintain a list of staff on site who can be called upon to translate if it is urgent. If the language is French, some of the people on that list are likely to be medical staff themselves]
I'd advise against attempts to translate the reports yourself, or over the internet, and let the doctors sort that out if they want to. All you need to do is to ensure he receives the appropriate referrals via his GP or via A&E if he is acutely unwell.
