The towering Northern Irishman entered the fray as a second-half substitute and, aside from a few surges down the left flank, he struggled to influence a contest which was settled by a well-worked JJ Lunney goal.
Jamie Walker was also pitched into action for the first time since Hearts rejected two bids for his services from Rangers, while Michael Smith and Ashley Smith-Brown made their debuts.
Perhaps predictably, given the number of new faces, it was a disjointed display in front of 105 travelling Hearts fans and, but for goalkeeper Victor Noring and the hosts’ wastefulness, the St Pat’s win would have been more handsome.
Yet it was Hearts who technically found the net first. Offering a tantalising glimpse of what looks a handy left-foot, summer signing Rafal Grzelak found the top corner with a stunning drive from the edge of the box. Sadly for the Pole, the whistle had already gone for an infringement.
And St Pat’s took full advantage of that reprieve on the 25-minute mark when Graham Kelly forged a path through the Hearts midfield before teeing up Lunney, who coolly finished from close range.
Walker was lively following his introduction and forced a fine block from defender Lee Desmond after dancing into the box, while Isma Goncalves shot wide after a mazy run.
Hearts’ marquee summer signing, Lafferty, replaced Cole Stockton on 72 minutes to a smattering of jeers from the Dublin locals, but did little to inspire a late rally.
l Deposed Hearts captain Perry Kitchen has left Tynecastle to join Danish outfit Randers.
The US international has signed a two-year contract with the Superliga side after leaving Hearts’ Irish training camp yesterday.
Kitchen, 25, was under contract with the capital club until summer 2018 but reached an agreement to cancel the remaining year on his deal, ensuring no fee will be involved.
He said: “I’m really looking forward to getting started. I had a really good time at Hearts, but the move to Randers FC was a really good opportunity for me, at the right time.”