The Hatters' captain also collapsed during his side's playoff-final game against Coventry City at Wembley just seven months ago, and the 29-year-old was later diagnosed with atrial fibrillation.
Lockyer watched on from a hospital bed surrounded by his family in May as Rob Edwards's side secured promotion to the Premier League for the first time.
However this weekend, the fixture between the Hatters and Bournemouth did not continue after the defender was stretchered off at around the hour mark, with the match set to be replayed in its entirety at a later date.
It has now emerged that Luton are likely to review their medical practices following the second incident involving Lockyer within the calendar year.
"This will be something we all look into more now. The physios, the club doctor, the specialists all did their work and worked with him in the summer and he was ok," said a source close to Lockyer, via the Daily Mail.
"It's just getting through this one test at a time. Comparing it to the summer will be something that happens when we know what went on on Saturday."
After collapsing during the Championship's showpiece event at the end of the 2022-23 season, Lockyer underwent surgery over the summer to treat the issue and was cleared to continue his career.
The Wales international has been a regular figure for the newly-promoted Hatters this term, starting 15 of his side's 16 Premier League matches, scoring one goal and providing one assist.
Starting alongside centre-back partners Amari'i Bell and Teden Mengi in the Luton backline, Lockyer and his Hatters teammates made a brilliant start in the match at the Vitality Stadium on the weekend, with Elijah Adebayo opening the scoring after six minutes.
Cherries target man Dominic Solanke restored parity in the contest for the hosts in the 58th minute, and moments later Lockyer collapsed off the ball.
All Premier League players are required to complete annual cardiac testing, but it is currently unknown whether the Welshman had undergone those tests since Luton returned to the top flight.
Luton will be back in action on Saturday when they face a daunting-looking trip to St James' Park, where Eddie Howe's Newcastle United await.