Could too much exercise cause a heart flutter?

Maybe, but....: As a general rule, exercise is more likely to reveal an underlying heart problem that was already there than to cause a heart problem.

New data: There is new data that suggests that long term endurance athletes are at increased risk for atrial fibrillation and atrial flutter later in life, possibly due to stretching of the top chambers of the heart. But this is far from conclusive, and a healthy lifestyle is still known as the best way to prevent heart disease.