[2] Maltsev made his NHL debut on 31 January 2021, in the Devils' 5–3 win over the Buffalo Sabres.

[4] On 15 July 2021, Maltsev was traded, along with a second-round pick in the 2021 NHL Entry Draft, to the Colorado Avalanche in exchange for Ryan Graves.

[5] Following two seasons within the Avalanche organization, Maltsev left as a free agent and was signed to a one-year, two-way contract with the Los Angeles Kings on 1 July 2023.

[6] Maltsev was placed on waivers following training camp with the Kings, and assigned to continue his career in the AHL with affiliate, the Ontario Reign.

Unable to earn a recall to the NHL, Maltsev left North America on loan by the Kings to return to the KHL in joining HC Spartak Moscow for the remainder of the season on 11 December 2023.