Isn't it also plausible that many people on low-sodium diets were at risk of heart attack or stroke already (and that's why they were on the low-sodium diet)?

Isn't it also plausible that many people on low-sodium diets were at risk of heart attack or stroke already (and that's why they were on the low-sodium diet)? Interesting result, for sure, and it'll be interesting to see the follow-up studies.