Krol, whose hire - on a brief to 're-energise' F-H's healthcare business across the Continent - was only unveiled in April, is thought to be set for a return to his native Holland.
A founder of Dutch agency Firm United - he sold his shares last year - Krol was unavailable to comment as PRWeek went to press. He left on 15 July.
F-H Europe regional director for the UK and South Africa Kevin Bell, now hunting a replacement to fill the London-based position, said: 'Patrick decided he wanted to work more in advertising than in PR.'
F-H is, nonetheless, believed to have won one new UK and one new pan-European chunk of healthcare business in the past fortnight. Details on both are currently undisclosed.
Separately, F-H healthcare account director Kath Young left last week and the company's public affairs associate director, Richard Mollet, has also quit. Both are to join Edelman (see opposite).
News of the exits comes just more than two months after F-H lost two staff to Edelman - senior account manager Louise Pontifex and account manager Sarah Hoffman (PRWeek, 13 May).