Well, I don't think that would be an issue with just an electrolyte-rich drink, but an energy-drink regimen would definitely be a problem. You already raise heart rate and blood pressure during the build-up to ejaculation, so you're making it much more dangerous if you're downing energy drinks as well, which also raise both of those.
If you're in good shape, you're probably still OK, but some people have weaker hearts than they think too, even gym rats or marathoners. But if you're the latter of those especially, you're most likely not in any danger. You're basically just trading one intense physical activity for another. Your ticker probably wouldn't even notice the difference.