The agency was informed of his decision this afternoon and his departure comes two months after the resignation of chief executive Victoria Fox – a move which threw Heath’s future at the agency into question.
In a statement, Heath said that his new role would be announced shortly and his departure leaves Lida with a leadership vacuum.
Heath said: "Lida has been an incredible experience for me. We have built up one of the most-admired agencies in our sector with a client list that is the envy of London. I couldn’t be leaving it in better hands. I am now greatly looking forward to starting a new role as a chief marketing officer; everything I have learnt at Lida will stand me in good stead".
Lida has suffered major accounts losses in the last year, such as the Boots loyalty and Ikea CRM accounts. The chief creative officer Trefor Thomas left last December after 18 months in the role and was replaced by Ben Golik, who joined from Rapp.
Moray MacLennan, the worldwide chief executive of M&C Saatchi, added: "Matthew has been instrumental to Lida’s extraordinary success over the past ten years. We do of course wish him the very best in his new client role. He leaves the agency in a strong position for future growth and we will be making announcements regarding the new leadership team in the near future."