Lucas made 247 Premier League appearances during a 10-year spell with Liverpool, scoring just one goal in the competition, before joining Serie A giants Lazio in 2017.
The former Brazil international then re-joined Gremio – the club where he began his career – after leaving Italy at the end of the 2021-22 campaign.
On Tuesday, Lucas tweeted a statement from the Gremio's medical department, announcing he would sit out the team's pre-season preparations while undergoing assessment.
The statement read: "The Gremio medical department communicates that the athlete Lucas Leiva presented, in pre-season routine exams, a picture of having an altered cardiac rhythm.
"Consequently, he is removed from physical activities until the conclusion of complementary exams and treatment of the condition."
Gremio – who have won the joint-most Copa Libertadores titles of any Brazilian club (three) – won promotion from Brazil's second tier in 2022 after finishing second.
Cavani is a free agent, having left Paris Saint-Germain at the end of his contract in June after seven successful seasons in Paris.
The club's all-time record goal-scorer with 200 in all competitions, Cavani has been linked with a host of European clubs including Inter, Bayern Munich and, more recently, Barcelona.
It has also been suggested the 33-year-old could choose to return to South America, with Gremio among the clubs said to be interested.
Vice-president Paulo Luz denied holding talks with Cavani's representative, but Romildo does not appear ready to abandon the dream of signing the Uruguay star.
"He [Cavani's agent] didn't make a proposal. But in life, if you don't talk, you don't know anything," he told Hora do Consular.
"Suddenly, there is chemistry, something different, empathy, a desire, and then suddenly it happens.
"Rationally, if things were under normal conditions, we wouldn't have the slightest expectation of bringing in this player because he wants to play in Europe, he will have offers a thousand times greater than those that a South American and Brazilian team can offer.
"Now, if he has it in his head, his idea, his desire, to do a project that is close to his home, close to his businesses and close to Uruguay, I believe he could sit down with us.
"I have this expectation that he has this feeling, and that he can talk to us a little more."
Cavani won 19 trophies, including six Ligue 1 titles, after joining PSG from Napoli in 2013 for a reported fee of €64million.
Liverpool and Barcelona great Suarez joined Gremio in January, having helped his boyhood club Nacional to the Uruguayan Primera Division title on his return to South America last year.
Suarez has scored four goals in 12 appearances in the Brazilian top flight this campaign, but his future is in doubt amid reports he is Miami's next big-name target.
Miami have already signed Suarez's former Barca team-mates Messi, Busquets and Alba, and Sunday brought confirmation they had traded with the San Jose Earthquakes to gain another international registration slot.
That move has heightened speculation regarding a move for Suarez, and while Lucas understands the draw of MLS, he hopes Gremio can keep the striker.
Asked about Suarez's future, Lucas – who retired in March after being diagnosed with a heart issue – said: "He made a fantastic impact here in Brazil at Gremio.
"I think made the right move. Luis is a world-class player, we don't need to speak about his qualities and what he's doing here in Brazil.
"He's been linked, but I just hope he can stay at Gremio because it's my club and he's my neighbour here!
"I hope he stays a bit longer but MLS is getting attention from every player and from the fans. It's normal that he will be linked with big teams like Inter Miami."
After Messi marked his Miami debut with a dramatic free-kick winner against Cruz Azul in the Leagues Cup, there has arguably never been a more compelling time to follow MLS.
Lucas is among those excited by the league's potential, adding: "MLS is growing every year, people are watching more MLS. If you look back maybe 10 years, nobody would have expected that.
"Americans know how to do these things, so well done to them. Messi going there will just attract a lot of fans and people who will be following the league, so it's great.
"It's great because football should be everywhere in the world because it is a fantastic sport that people love to watch.
"We can see him in another league, not in Europe. In America, it's a great thing for the fans that love football. It's a league that is improving and is growing and getting better every season."
Uruguay striker Suarez joined the Brazilian club this month after helping boyhood club Nacional win the title back home in a brief spell ahead of the World Cup.
The 35-year-old promised goals as he signed a two-year contract at Gremio, and his bow certainly delivered that.
Facing Sao Luiz in a one-off match for the Recopa on Tuesday, Suarez's three goals had a 4-1 win wrapped up before half-time.
It was the first time Suarez had scored a first-half hat-trick in almost 10 years, last doing so for Liverpool against Norwich City in December 2013.
"Luisito's story couldn't start better here," read Gremio's Twitter page after Suarez had volleyed in his third.
Suarez was a free agent after leaving Nacional ahead of the World Cup in Qatar, at which he started two of Uruguay's three games as they suffered a surprise group-stage exit.
The former Liverpool, Barcelona and Atletico Madrid striker penned a two-year contract with Gremio – who won promotion back to the Brazilian top flight after a one-season spell in Serie B last term – on New Year's Eve.
Asked whether joining Gremio represented his biggest challenge, Suarez told the club's media channels: "It could be, but I can also compare it with my time at Atletico Madrid.
"I won the league with Atletico when Real Madrid and Barcelona dominated football in Spain.
"This one might be even more difficult, but I am convinced we have an incredible team and a coach that does things well and that has a great influence.
"I always liked challenges. Coming to a club with so much history, a great club from Brazil, always gives you hope.
"For a team to come from Serie B and want to fight with the best in Brazilian football is a very nice challenge, for Gremio to return to where it deserves to be, among the teams that go to the Copa Libertadores, to be fighting up there and creating a good team."
Suarez scored eight times in 14 appearances as Nacional won the Primera Division title last year, and though the 35-year-old admits he is no longer the player he once was, he is confident he can make a difference.
"I am not the Luis Suarez of 2015, 2016 or 2013. I am not. I am not stupid," he said.
"I am not going to run 50 metres, because I am not that player anymore.
"But maybe with my movement 50 metres from goal, my team-mates can benefit, because it is a team game. What I am going to promise is compromise, comradery, attitude, hunger and goals."
Suarez was reunited with his former Liverpool team-mate when he joined Gremio in December, though was unable to take to the field with the Brazilian midfielder.
Lucas had already been forced to withdraw from training earlier that month after the discovery of a heart issue was made during a routine screening.
After spending some time to evaluate and undergo further tests, the 36-year-old confirmed at a press conference on Friday that he had decided to call time on his playing days on doctors' advice.
Suarez – who played for Liverpool alongside Lucas between 2011 and 2014 – paid tribute to him after opening the scoring for Gremio at Ypiranga by revealing a written message on his under-shirt which read: "Lucas, our heart is with you, we are together".
Gremio's players also wore shirts with Lucas' name on the back, while head coach Renato Portaluppi adorned a t-shirt with the player's name.
Ypiranga went on to win 2-1 in the first leg of their Campeonato Gaucho semi-final through a 96th-minute penalty from Erick, with the second leg due to take place at Arena do Gremio on Saturday.
Suarez is reportedly in talks with Miami over a move which would see him reunited with former Barcelona team-mates Lionel Messi, Jordi Alba and Sergio Busquets.
The Uruguayan is seemingly closing in on a one-year deal with the MLS outfit after spending 2023 with Gremio, who finished second to Palmeiras in their first season back in Brazil's top flight, having spent the previous campaign in the second tier.
Suarez scored 17 league goals for Gremio throughout the year, also adding 11 assists to give him the most total goal involvements (28) in the Brasileirao.
The striker, who will turn 37 in January, hit 27 goals across all competitions before departing as a free agent, and recently retired defender Chiellini says he would thrive in MLS.
"You see what Suarez did this year in Brazil… Brazil is not considered a weak league," Chiellini, who was famously bitten by Suarez at the 2014 World Cup, told Stats Perform.
"Suarez scored almost 30 goals, we still see something there and it's still really good. Now football is changing all over the world.
"There are less differences between some leagues in Europe and other countries. The only league that's very different from every other one, I think, is the Premier League.
"But to be honest, the other ones we can compare, and you can also find good players in some weird leagues that some years ago you never considered. Now it is very different."
That is according to Suarez's former Atletico Madrid team-mate Hector Herrera, who says the Uruguayan is a "winner" and would face no problems in adapting to the league.
Suarez has been strongly linked with a move to Miami, where Messi, Sergio Busquets and Jordi Alba have all been reunited with former Barcelona boss Gerardo Martino.
Having won LaLiga five times during eight years in Spain with Barca and Atleti, Suarez returned to his boyhood club Nacional in 2022 before heading to Brazil to join Gremio for 2023.
Reports suggest Suarez may join Miami as a free agent after Gremio coach Renato Gaucho confirmed he is set to depart on Saturday, and Herrera believes MLS would be the perfect destination for the 36-year-old.
"Hopefully he can come to this league and help it continue to grow," the Houston Dynamo midfielder, who played with Suarez in Madrid between 2020 and 2022, told Stats Perform.
"With the quality of player he is and as a person, he will surely help any team that he comes to. It would be a pleasure to see him and face him again.
"He has played in many leagues, in many teams, and I don't think it will be difficult for him to adapt because he is a winner.
"Obviously we know that he will contribute a lot to the team that he goes to, and to the whole league as well."
Suarez leads all Gremio players for goals (15) and assists (12) in the Brazilian top flight this season, with the team currently sitting in fourth after winning promotion back to the first tier last year.
Herrera feels he would be a real asset for Miami, who won the first trophy in their history in August as Messi led them to glory in the Leagues Cup.
Asked about the prospect of Suarez teaming up with Messi, Herrera said: "I have no doubt that he could go to that team because I know that they are great friends and their families have a good relationship.
"It makes sense for him to come to Inter Miami. Messi's arrival gave another face and another perspective to the league and will help it grow.
"We are talking about the current winner of the Ballon d'Or and it is a pleasure to have him in the league, to be able to face him and make MLS continue to grow.
"We have seen the level that he has shown since he arrived, and surely next year will be even better."
