A high-end art dealer was robbed at knifepoint in his Upper East Side pad by a handyman who took off with some cash — but left a showroom full of pricey artwork on the walls, officials said.

Paul Quatrochi, whose stable of wealthy collectors includes Penthouse publisher Bob Guccione, Baron Heinrich von Thyssen and Austrian Princess Michaela von Hapsburg, said he had a knife pressed against his throat for nearly 30 minutes while his guest rifled through his pockets and stole $300 in cash.