I have Atrial fibrillation ( AFib or AF), can a car accident have caused it?

I’m 77 yrs old but had been in great physical shape, very active in sports, biking, & around the house & yard, etc. Then I was injured in a freak accident 8/30/17 when a car crashed into a building where I was a customer, sending me to emergency vascular surgery for compartment syndrome (R. calf.) I spent 4 days in hospital, had 2 surgeries in that period, & am now assigned to Physical Therapy for several mos. About 10 days after the accident, my vascular surgeon referred me to a cardiologist for heartbeat concerns just noticed by him; I’m now diagnosed with A. Fib, on blood thinners for rest of my life, & had a cardioversion in 10/2017. My cardiologist says because I hadn’t had an EKG prior to my accident, he can’t say that the AFib was caused by the accident & the resulting horrific stress (for example, I was told by the ER doc that my leg might be amputated, had to undergo gen. anesthesia, of which I am very leery, & have been forced to spend more time idle in the last 3 mo. than ever in my life – I NEED to be active.)

Prior to my accident, my only health issues were hypertension (well-controlled via meds) & a bum knee; I’d been seeing my primary care doc at least annually.

Do you feel the accident may be implicated in my 9/2017 diagnosis of A Fib?

Age: 77
Medications: warfarin (now!); lisinopril; hydrochlorothiazide