Former England scrumhalf Ben Youngs underwent heart surgery after collapsing during an open training session with Leicester Tigers.
Youngs is England's most-capped men's player and has been diagnosed with an irregular heartbeat and tachycardia.
The 34-year-old had surgery after the incident but has said he should be fit for the start of the new Premiership season in September.
Youngs did not specify the date of his collapse.
Youngs retired from international rugby after the 2023 World Cup and had 127 caps for England over his 13-year career.
The Leicester Tiger player said on the Love Of Rugby podcast: "You know when we joked around on the pod quite a while back, and we had this open training session at Leicester, and I said I was doing fitness, and basically I collapsed.
"Well, not collapsed, but I had to stop and lay down as my heart was pounding away ... And I thought: 'This is it, this is how I'm gonna go.'
"I've basically had a few of these episodes and I've had it my whole life. It can just kind of spontaneously happen at any stage of your life or career. And so I have had it my whole life, unknown to me."