exhibit 10. 4 400 east jamie court. suite 102 south san francisco, ca 94080 phone ( 650 ) 741 · 0900 fax ( 650 ) 741 · 0901 myokardia. com september 19, 2013 anastasios gianakakos re : employment by myokardia, inc. dear tassos : myokardia, inc. ( the “ company ” ) is pleased to confirm its offer to employ you as chief executive officer ( ceo ). as ceo you will be reporting to the myokardia board of directors ( bod ). in the role of ceo, you will : • work with the bod and senior management to formulate and communicate a compelling vision and strategic direction and value creation plan for the company ; evaluate alternative strategies ; identify competitive issues ; capitalize on platform technology and develop and implement operating plans to achieve objectives. • oversee all company activities to ensure myokardia meets its research, development, and financial milestones and all other objectives including clinical, regulatory, and business development. • develop and maintain strategic partnerships with external companies, overseeing critical activities to ensure research and development commitments and related projects are fulfilled. • serve as the primary spokesperson for company, establishing and communicating the company ’ s image, and enhancing its visibility among potential partners. • build additional organizational experience within the management team. work with the board and senior management team to manage uncertainty while maintaining an entrepreneurial environment. • ensure that qualified research and development and managerial personnel are attracted and retained ; manage performance by providing feedback, teaching and development opportunities. • represent myokardia in scientific conferences, presentations, industry and investment groups. • build and maintain solid working relationships with key opinion leaders and investors. • foster an internal atmosphere that supports individual accountability, transparency, open communication and respect to enable employees to focus on the company ’ s mission. your effective date of hire as a regular employee ( the “ start date ” ) will be october 14, 2013. your compensation for this position will be at the rate of $ 375, 000 per year, payable monthly in accordance with the company ’ s normal pay schedule. you will be eligible to participate each year in the company ’ s annual target bonus pool plan of up to 35 % of your base salary based upon achievement of both corporate and personal goals, as agreed to between you and the bod. you must be employed on the date on which the annual bonus is paid in order