Just had a guy the other day same thing (not BLS crew, no ALS in the area) - 62 yr old male, feeling unwell at work. Taken to medical clinic (very loose term) and an hour later we were called for some "cardiac problem"
Guy was in V-tach at 220, with weak radials at about 100 bpm and a BP around 100. Pt extremely diaphoretic, pale, nauseous, vomited x1, denies any sort of pain anywhere. Pt hx of same 6 years ago and converted with drugs - only med was atenolol.
He was stable, conscious an only c/o feeling nauseous all the way to the hospital (4 min drive) - they attempted electrical cardioversion - nothing. But after one dose of amiodarone - NSR at 88bpm within 30 secs.
Sometimes you just never know who will or won't make it.