Sen. Bernie Sanders (I-Vt.) underwent an emergency heart procedure on Tuesday evening, and Stephen Colbert has a theory about how it was possible.

“He was hospitalized for treatment of an artery blockage,” “The Late Show” host said. “It’s what happens when people want a president who has a heart.”

Sanders was hospitalized following a campaign event on Tuesday and doctors inserted two stents. His campaign released a statement saying he was “conversing and in good spirits” but would be resting over the coming days.

Colbert also joked about Sanders’ appearance on the show a week earlier, during which he had “knocked on wood” about his health.

Watch the “Late Show” segment below to hear the punchline: